Amine-functionalized magnetic bamboo-based activated carbon adsorptive removal of ciprofloxacin and norfloxacin: A batch and fixed-bed column study

State-of-the-art progress and prospect of metal-organic frameworks and composites for photoelectrochemical amino-drugs sensing

Unregulated discharge of antibiotics in waterbodies has posed a significant threat to the aquatic flora and fauna in post-pandemic times. This alarming situation has ascertained the need for suitable sensors to detect persistent antibiotic residues. In this context, functional hybrid materials centralized on reticular metal-organic frameworks (MOFs)/composites have been a research hot spot for photoelectrochemical host-guest recognition events over the past two decades. The unique amalgamation of the robust framework, ease of synthesis, and tunable photophysical properties complemented with in silico approaches render these materials highly promising for recognition events over other contemporaries. The present review provides a critical analysis of the state-of-the-art advancement of MOFs along with their allied composites toward the detection of targeted amino-drug residues (nitrofurazone, norfloxacin, ciprofloxacin, tetracycline, acetaminophen) within the last quinquennial period (approximately 2019-2024). Detection of the targeted drug residues by electrochemical and fluorometric pathways and their host-guest mechanistic pathways have been precisely described. Additionally, different functionalization methods and luminescence strategies with their structural viewpoint have been concisely summarized. Moreover, we delve into the futuristic possibility of integrating artificial intelligence (AI) and machine learning (ML) for better quantification of antibiotics. Finally, the unmet challenges and future research directions of the current research strategies have been outlined for automatic ML (AutoML) assisted next-generation POCT device fabrication.

Exploring the state-of-the-art in metal-organic frameworks for antibiotic adsorption: a review of performance, mechanisms, and regeneration

The application of metal-organic frameworks (MOFs) towards the adsorption of antibiotics is a new and emerging area of study. The rise in use or misuse of antibiotic products has exacerbated their ongoing presence and persistence in the natural environment. Even at low concentrations, antibiotic residues exert pressure on bacterial populations, eventually leading to the emergence of resistant bacteria. Metal-organic frameworks, known for their high porosity, vast specific surface area, and ease of modification, have emerged to be a promising and sustainable antibiotic adsorbent. In an effort to advance the development of this adsorbent, this study provides a state-of-the-art review of recent research published from 2020 to the present, specifically examining the use of MOFs for removing antibiotics from aqueous solutions. Multiple MOF adsorbents were analyzed, with approximately 59% demonstrating significant adsorption capacity within the pH range of 6.0-8.0. In 75% of the instances, the adsorption system reached equilibrium in under 2 hr. Adsorption capacities compared well to other published works in the literature and exceeded conventional adsorbents in many instances. Notable cases of MOF performance were MIL-53(Al) adsorption of amoxicillin (AMX) and SA-g-P3AP@MOF(Fe)/Ag adsorption of neomycin where adsorption capacities of 758.5 and 625.0 mg/g were attained, respectively. The reusability of MOFs was extensively reported at the laboratory batch scale. Analysis of the reported studies revealed the most effective eluents were acetone, ethanol, and methanol, with mostly 3-5 cycles attainable without appreciable loss in efficiency. The recent literature confirmed that MOFs are highly efficient in the adsorption of antibiotics; however, there are some areas that warrant further development. It is intended that this work will bring recent trends to the forefront, identify knowledge gaps, and help guide future research proposals.

Including the rare cubane cluster cobalt coordination polymer as the fluorescent sensing material for selectively and sensitively detecting the nitrofurantoin antibiotic

More and more attention has been paid to food safety. Due to the overuse and misuse of antibiotics, the problem of antibiotic residues in animal food is one of the important challenges to ensure food safety. The development of a feasible strategy to detect antibiotic residues in animal food has become desirable. In this paper, we creatively synthesize a water-stable fluorescence sensing material, namely, Co(Ⅱ)-Coordination polymer [Co2(CA) (L)0.5 (H2O)3] n (L = 1,4-bis(imidazole-1-ylmethyl) benzene, CA= Citric acid). The single crystal X-ray diffraction shows that it crystallizes in tetragonal space group I-4. It is worth mentioning that there exists the rare Co4(μ3-O)4 cubane cluster structure and Co8 cluster units. Those adjacent Co8 cluster units are connected into an infinite two-dimensional net structure by four flexible bridged L ligands. Finally, the Co(Ⅱ)-Coordination polymer (CP) further develops into the three-dimensional supramolecular structure via the hydrogen bonds of O-H⋯O and C-H⋯O. It could selectively detect the antibiotic-nitrofurantoin (NFT) residue by way of fluorescence quenching, Co-CP for the detection of NFT shows broad linearity from 0 to 200 μM, with a detection limit of 0.13 μM and strong anti-interference ability. It is used to detect the NFT residual of tap water and milk with a spiked recovery of 86.35-112.47 %.

Acylhydrazone-functionalized starch for efficient removal of hazardous dyes, heavy metal ion, and sulfides from wastewater: Adsorption behavior and mechanism analysis

Herein, a novel acylhydrazone biosorbent (GSL) with abundant three-dimensional porous structure was successfully prepared by using low-cost starch as raw material for water pollution remediation applications. Various analytical techniques were applied to characterize the morphological structure and chemical composition. Interestingly, the adsorption efficiency of the adsorbent towards Malachite green (MG), Safranin O (SO), Cu2+, and sulfide in the static adsorption experiment was extremely high due to presence of ample functional groups. Additionally, the adsorption isotherm and kinetic experiments revealed that the adsorption processes were based on monolayer chemisorption. The maximum sorption amounts were 2237.4961 mg/g for SO, 2101.6610 mg/g for MG, 410.7019 mg/g for Cu2+, and 483.0194 mg/g for sulfides at 298.15 k. The thermodynamic analysis also demonstrated that all adsorption processes were spontaneous heat processes. The adsorption mechanism was analyzed by FTIR, SEM-EDAX and XPS. The adsorption of SO onto GSL reached 1025.8617 mg/g in continuous adsorption experiments, and the experimental data were fitted through the Thomas model and Yoon-Nelson model. Furthermore, the GSL showed good reusability and salt resistance. Importantly, starch-based acylhydrazone as the adsorbent for the simultaneous removal of hazardous dyes, heavy metal ions and sulfhides has not yet been seen reported.

Solvent-free synthesis of defective Zr-based metal-organic framework from waste plastic bottles for highly efficient lomefloxacin removal

Large amount of polyethylene terephthalate (PET) plastics waster and emerging contaminants in water, including fluoroquinolone antibiotics, pose challenges to human survival. In this work, a green synthesis scheme is proposed in which the defective UiO-66 (d-UiO-66) is fabricated via a solvent-free routine by using PET plastics waster as raw materials for lomefloxacin (LOM) removal. In comparison with defect-free UiO-66, the created defect imparts d-UiO-66 with higher porosity and abundant defective Zr sites, which are beneficial to boost LOM adsorption. As expected, d-UiO-66 exhibited excellent LOM adsorption performances, showcasing a saturation adsorption capacity of 588 mg g-1 and a kinetic rate constant of 0.204 g mg-1 h-1, which are 3.5 and 2.0 times higher than those of the pristine UiO-66, respectively. Remarkably, the LOM saturation adsorption capacity of d-UiO-66 surpasses that of all reported adsorbents. Mechanism study reveals that this outstanding adsorption performance of d-UiO-66 is mainly ascribed to the abundant defective sites, high porosity, together with the strong hydrogen bonding interaction and π-π stacking interaction between d-UiO-66 and LOM. Therefore, the d-UiO-66 obtained by the solvent-free method can not only effectively upcycle PET plastic waster, but also efficiently remove LOM, demonstrating a potential routine to simultaneous address the solid PET waster and wastewater.

Preparation of Pt and bamboo charcoal co-modified TiO2 for formaldehyde sensing at room temperature

Anatase TiO2 has evolved into one of the most attractive materials for gas sensing owing to its strong oxidation activity and excellent sensing properties. In this study, we prepared Pt and bamboo charcoal co-modified nano-TiO2 using a one-pot hydrothermal process and applied it to detect formaldehyde. The successful incorporation of the precious metal Pt and bamboo charcoal onto TiO2 was confirmed by scanning electron microscope, transmission electron microscopy, energy dispersive spectrometer, X-ray diffraction and X-ray photoelectron spectroscopy. Detailed analysis revealed a homogeneous distribution of Pt nanoparticles and bamboo charcoal on the TiO2 surface, which significantly improved the surface area and facilitated gas adsorption. These modifiers significantly enhanced the response of TiO2 to formaldehyde, for instance, the response signal increased fourfold, while the response time decreased from 91 to 68 s. The sample with 0.5@Pt and 0.5@C bamboo charcoal performed the best, showcasing the synergistic effect of metal nanoparticles and carbonaceous materials on gas-sensing properties. Our work highlighted the potential of using biomass-derived carbon to enhance the detection of formaldehyde and demonstrated the importance of material characteristics in designing effective gas sensors.

Performance and mechanism of sulfadiazine and norfloxacin adsorption from aqueous solution by magnetic coconut shell biochar

In this study, magnetic coconut shell biochar loaded with spherical Fe3O4 and γ-Fe2O3 particles was successfully synthesized using a chemical coprecipitation method. The magnetic biochar exhibited a good magnetic separability and environmental security. The maximum sulfadiazine (SDZ) and norfloxacin (NOR) removal efficiencies were 94.8% and 92.3% at pH 4 and 25 °C with adsorbent dosage of 2.5 g/L, respectively. When antibiotic concentrations ranged from 5 to 50 mg/L, the theoretical maximum adsorption capacities of SDZ and NOR were 16.7 mg/g and 25.8 mg/g, respectively. The Langmuir isotherm and pseudo-second-order kinetic models could better describe the adsorption process of both antibiotics, implying the monolayer chemical adsorption. The thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic. The ionic strength had no significant effect on the adsorption behavior of either antibiotic. Combined with BET, FTIR, and XPS results, the dominant mechanisms for SDZ and NOR adsorption were pore filling, π-π electron-donor-acceptor interaction, hydrogen bonds and surface complexation. Moreover, Lewis acid-base interaction also contributed to SDZ adsorption.

Monolayer Adsorption of Ciprofloxacin on Magnetic Inulin/Mg-Zn-Al Layered Double Hydroxide: Advanced Interpretation of the Adsorption Process

In this study, magnetic inulin/Mg-Zn-Al layered double hydroxide (MILDH) was synthesized for the adsorption of ciprofloxacin. The application of various analytical techniques confirmed the successful formation of MILDH. For the optimization of controllable factors, Taguchi design was applied and optimum values were obtained as equilibrium time─100 min, adsorbent dose─20 mg, and ciprofloxacin concentration─30 mg/L. The highest capacity of the material was recorded as 196.19 mg/g at 298 K. Langmuir model (R2 = 0.9669-0.9832) fitted best as compared to the Freundlich model (R2 = 0.9588-0.9657), concluded the monolayer adsorption of ciprofloxacin on MILDH. Statistical physics model M 2 was found to fit best to measured data (R2 = 0.9982-0.9989), indicating that the binding of ciprofloxacin took place on two types of receptor sites (n1 and n2). The multidocking mechanism with horizontal position was suggested on the first receptor site (n1 < 1), while multimolecular adsorption of ciprofloxacin lying vertically on the second receptor site (n2 > 1) at all temperatures. The adsorption energies (E1 = 22.79-27.20 kJ/mol; E2 = 18.00-19.46 kJ/mol) illustrated that the adsorption of ciprofloxacin onto MILDH occurred through physical forces. Best fitting of the fractal-like pseudo-first-order kinetic model (R2 = 0.9982-0.9992) indicated that the adsorption of ciprofloxacin happened on the MILDH surface having different energies. X-ray photoelectron spectroscopy analysis further confirmed the adsorption mechanism of ciprofloxacin onto MILDH.

Towards sorptive eradication of pharmaceutical micro-pollutant ciprofloxacin from aquatic environment: A comprehensive review

Antibiotics are widely prioritized pharmaceuticals frequently adopted in medication for addressing numerous ailments of humans and animals. However, the non-judicious disposal of ciprofloxacin (CIP) with concentration levels exceeding threshold limit in an aqueous environment has been the matter of growing concern nowadays. CIP is found in various waterways with appreciable mobility due to its limited decay in solidified form. Hence, the effective eradication strategy of this non-steroidal anti-inflammatory antibiotic from aqueous media is pivotal for preventing the users and the biosphere from their hazardous impacts. Reportedly several customary techniques like reverse osmosis, precipitation, cross-filtration, nano-filtration, ion exchange, microbial remediation, and adsorption have been employed to eliminate CIP from water. Out of them, adsorption is ascertained to be a potential method because of lesser preliminary investment costs, ease of operation, greater efficiency, less energy usage, reduced chemical and biological slurry production, and ready availability of precursor materials. Towards remediation of ciprofloxacin-laden water, plenty of researchers have used different adsorbents. However, the present-day challenge is opting the promising sorbent and its application towards industrial scale-up which is vital to get reviewed. In this article, adsorbents of diverse origins are reviewed in terms of their performances in CIP removal. The review stresses the impact of various factors on sorptive assimilation of CIP, adsorption kinetics, isotherms, mechanism of ionic interaction, contrivances for CIP detection, cost estimation and reusability assessments of adsorbents also that may endorse the next-generation investigators to decide the efficacious, environmental appealing and cost-competitive adsorbents for effective riddance of CIP from wastewater.

Effect and mechanism of norfloxacin removal by Eucalyptus leaf extract enhanced the ZVI/H2O2 process

The conventional ZVI/H2O2 technology suffers from poor reagent utilization, excess iron sludge generation, and strong low pH dependence. Therefore, eucalyptus leaf extract (ELE) was introduced to improve ZVI/H2O2 technology, and the efficacy and mechanism of ELE promoting ZVI/H2O2 technology were deeply explored. The results showed that the norfloxacin (NOR) removal and kobs of the ZVI/H2O2/ELE process were enhanced by 35.64 % and 3.27 times, respectively, compared to the ZVI/H2O2 process. In the ZVI/H2O2 process, the production of three reactive oxygen species (ROS: 1O2，·O2-，·OH) was effectively promoted by ELE so that the reaction efficacy was significantly enhanced. Moreover, the attack and degradation of pollutants by ROS was the main way to remove pollutants. With the introduction of ELE, the reactive sites on the catalyst appearance were increased to some extent, and the Fe(III)/Fe(II) cycle was improved. The analysis showed that ELE is rich in titratable acids and the ZVI/H2O2 technology is promoted mainly by lowering the pH of the process. In addition, the chelation of ELE and the reduction in pH by the ELE synergistically enhanced the ZVI/H2O2 technology, which significantly improved the reagent utilization (4.70 times for ZVI and 3.03 times for H2O2), broadened the pH range of the technology (6-9) and was able to effectively reduce the iron sludge contamination (30.33 %) of the process. Therefore, the study offers an important value to study eucalyptus leaves in micron-scale ZVI-Fenton technology.

Harnessing the Chemical Functionality of Metal-Organic Frameworks Toward Removal of Aqueous Pollutants

Wastewater treatment has been bestowed with a plethora of materials; among them, metal-organic frameworks (MOFs) are one such kind with exceptional properties. Besides their application in gas adsorption and storage, they are applied in many fields. In orientation toward wastewater treatment, MOFs have been and are being successfully employed to capture a variety of aqueous pollutants, including both organic and inorganic ones. This review sheds light on the postsynthetic modifications (PSMs) performed over MOFs to adsorb and degrade recalcitrant. Modifications performed on the metal nodes and the linkers have been explained with reference to some widely used chemical modifications like alkylation, amination, thiol addition, tandem modifications, and coordinate modifications. The boost in pollutant removal efficacy, reaction rate, adsorption capacity, and selectivity for the modified MOFs is highlighted. The rationale and the robustness of micromotor MOFs, i.e., MOFs with motor activity, and their potential application in the capture of toxic pollutants are also presented for readers. This review also discusses the challenges and future recommendations to be considered in performing PSM over a MOF concerning wastewater treatment.

Isolation of a Cd-Based Coordination Polymer Containing Mixed Ligands: Time- and Temperature-Dependent Synthesis, Sulfonamide Antibiotics Detection, and Schottky Diode Fabrication

In this study, we present a new cadmium(II)-based two-dimensional coordination polymer [Cd (L)(NA)(H2O)] (L = Iminol form of N-nicotinoyl glycinate, NA = nicotinate), 1, containing two linkers generated from N-nicotinoyl glycine. A comprehensive investigation was carried out during the synthesis of the coordination polymers by varying the reaction time interval and temperature, and it revealed the formation of three distinct phases, of which two phases were previously reported and one was a new compound (1). The structure of compound 1 was determined by single-crystal X-ray diffraction, and it shows a corrugated layer structure with hydrogen bond interactions leading to three-dimensional supramolecular arrangements. Compound 1 exhibited strong emission at 420 nm when excited at 260 nm in an aqueous medium. The emission behavior of this compound was used for the detection of various sulfonamide antibiotics, sulfadiazine, sulfamethazine, sulfachloropyridazine, sulfameter, sulfaquinoxaline, and sulfathiazole, in the presence of common water pollutants. The luminescence quenching response of compound 1 to sulfonamide antibiotics was significant, ranging from 81 to 94%, and the detection sensitivity reached parts per billion (ppb) levels (226-726 ppb). Compound 1 also used for the fabrication of Schottky diode devices with a barrier height of 0.86 eV along with an excellent ideality factor of 1.24.

Rice husk hydrochar prepared by hydrochloric acid assisted hydrothermal carbonization for levofloxacin removal in bioretention columns

Hydrochars are promising adsorbents in pollutant removal for water treatment. Herein, hydrochloric acid (HCl) co-hydrothermally treated hydrochars were prepared from rice husk biomass at 180 °C via a one-step hydrothermal method. Adsorption behaviors of levofloxacin (LVX) on hydrochars were evaluated. The specific surface area and pore volume of the hydrochar synthesized in 5 mol/L HCl (5H-HC) were almost 17 and 8 times of untreated hydrochar, respectively. The 5H-HC sample exhibited the highest LVX adsorption capability at room temperature (107 mg/g). Thermodynamic experimental results revealed that adsorption was a spontaneous endothermic process. Yan model provided the best description of the breakthrough behavior of LVX in bioretention column, indicating that the adsorption on the samples involved several rate-limiting factors including diffusion and mass transfer. The results show that facile HCl co-hydrothermal carbonization of waste biomass can produce novel hydrochars with high LVX adsorption ability.

Environmental remediation of the norfloxacin in water by adsorption: Advances, current status and prospects

Antibiotics are considered as the new generation water pollutants as these disturb endocrine systems if water contaminated with antibiotics is consumed. Among many antibiotics norfloxacin is present in various natural water bodies globally. This antibiotic is considered an emerging pollutant due to its low degradation in aquatic animals. Besides, it has many side effects on human vital organs. Therefore, the present article discusses the recent advances in the removal of norfloxacin by adsorption. This article describes the presence of norfloxacin in natural water, consumption, toxicity, various adsorbents for norfloxacin removal, optimization factors for norfloxacin removal, kinetics, thermodynamics, modeling, adsorption mechanism and regeneration of the adsorbents. Adsorption takes place in a monolayer following the Langmuir model. The Pseudo-second order model represents the kinetic data. The adsorption capacity ranged from 0.924 to 1282 mg g-1. In this sense, the parameters such as the NFX concentration added to the adsorbent textural properties exerted a great influence. Besides, the fixed bed-based removal at a large scale is also included. In addition to this, the simulation studies were also discussed to describe the adsorption mechanism. Finally, the research challenges and future perspectives have also been highlighted. This article will be highly useful for academicians, researchers, industry persons, and government authorities for designing future advanced experiments.

Adsorption of tetracycline by polycationic straw: Density functional theory calculation for mechanism and machine learning prediction for tetracyclines' remediation

The abuse of antibiotics causes serious environmental pollution, whose removal has become a hot topic. The adsorption of tetracycline (TC) on a prepared polycationic straw (MMS) was investigated. The kinetic, thermodynamic and adsorption isotherm models showed that adsorption of TC by MMS was a spontaneous, monolayer reaction with coexistence of physical and chemical process. Density functional theory indicated that the adsorption of TC resulted from electrostatic interaction and hydrogen bonds, which proved the mechanism of TC by macromolecular biomass for the first time. The expected and empirical values of TC adsorption showed a high fit degree, through predication of machine learning, indicating the feasibility and avoiding lots of experiments. Further, the adsorption ability of MMS to other TCs was predicted, founding that the highest removal efficiency was doxycycline, which provides a novel strategy for removal of other pollution and reduce of economic and time cost in practical application.

The Impact of Surface Chemistry and Synthesis Conditions on the Adsorption of Antibiotics onto MXene Membranes

MXene, a two-dimensional (2D) nanomaterial with diverse applications, has gained significant attention due to its 2D lamellar structure, abundance of surface groups, and conductivity. Despite various established synthesis methods since its discovery in 2011, MXenes produced through different approaches exhibit variations in structural and physicochemical characteristics, impacting their suitability for environmental application. This study delves into the effect of synthesis conditions on MXene properties and its adsorption capabilities for four commonly prescribed antibiotics. We utilized material characterization techniques to differentiate MXenes synthesized using three prevalent etchants: hydrofluoric acid (HF), mixed acids (HCl/HF), and fluoride salts (LiF/HCl). Our investigation of adsorption performance included isotherm and kinetic analysis, complemented by density functional theory calculations. The results of this research pinpointed LiF/HCl as an efficient etchant, yielding MXene with favorable morphology and surface chemistry. Electrostatic interactions and hydrogen bonding between MXene surface terminations and ionizable moieties of the antibiotic molecules emerge as pivotal factors in adsorption. Specifically, a higher presence of oxygen terminations increases the binding affinities. These findings provide valuable guidance for etchant selection in environmental applications and underscore the potential to tailor MXenes through synthesis conditions to design membranes capable of selectively removing antibiotics and other targeted substances.

Tri-modified ferric alginate gel with high regenerative properties catalysts for efficient degradation of rhodamine B

Water pollution caused by dyes has become a focal point of attention. Among them, the heterogeneous Fenton reaction has emerged as an effective solution to this problem. In this study, we designed a ferric alginate gel (PAGM) tri-modified with poly(vinyl alcohol), graphene oxide, and MoS2 as a heterogeneous Fenton catalyst for organic dye degradation. PAGM addresses the drawbacks of alginate gel, such as poor mechanical properties and gel chain dissolution, thereby significantly extending the catalyst's lifespan. The removal rate of rhodamine B by PAGM reached 95.5 % within 15 min, which was 5.9 times higher than that of unmodified ferric alginate gel. Furthermore, due to the π-π interactions, PAGM exhibits unique adsorption properties for pollutants containing benzene rings. Additionally, PAGM can be regenerated multiple times through a simple soaking procedure without any performance degradation. Finally, the reaction column constructed with PAGM maintained an 83.5 % removal rate even after 319 h of continuous wastewater treatment. This work introduces a novel concept for the study of alginate-based gel catalysts in heterogeneous Fenton reactions.

Mechanistic evaluation in the removal of chlorpheniramine and ciprofloxacin on activated carbons

Chlorpheniramine (CPM) and Ciprofloxacin (CIP) adsorption onto a granular (GAC) and pelletized activated carbon (PAC) analyzing the physicochemical mechanisms involved using the carbon's characterization were studied. Adsorption isotherm studies were performed at temperatures of 25 °C at pH values of 4, 7 and 9 and at 45 °C at a pH of 7. The characterization demonstrated that GAC has a predominantly acid character due to its predominantly negative surface charge and acidic site concentration alongside the characteristic bands detected in the X-ray Photoemission Spectroscopy (XPS) study. On the other hand, PAC presented a mostly basic character due to its positive surface charge and basic site concentrations. The adsorption isotherm studies demonstrated that the Freundlich isotherm better described the equilibrium data with an average deviation percentage of 7.45 and 6.74 for GAC and PAC. The temperature and desorption studies demonstrated that the adsorption process occurs through a chemisorption mechanism, and the pH study alongside the GAC and PAC characterization demonstrated that the mechanisms involved are a combination of electrostatic interactions and pi-pi interactions between the CPM and CIP molecules and the carbon's surface. These results demonstrate that the adsorption process of these pharmaceutical compounds is done through a combination of physical and chemical interactions.

Production of MgFe2O4/activated carbons derived from a harmful grass Cynodon dactylon and their utilization for ciprofloxacin removal

Cynodon dactylon, an invasive species, exhibits its robust adaptability, reproduction and nutrient regime against the local species. Taking advantage of this harmful grass as a raw precursor to produce valuable materials for wastewater treatment has paid much attention. Herein, we report on the fabrication of Cynodom dactylon derived MgFe2O4@AC with a main goal of effective removal of ciprofloxacin antibiotic from water. Our findings showed that MgFe2O4@ACK1 composites attained mesoporous textures, high specific surface areas (884.3-991.6 m2 g-1), and MgFe2O4-20%@ACK1 was the most effective with a very high removal efficiency of 96.7%. The Elovich model was suitable for describing the kinetic of adsorption with (Radj)2 of 0.9988. Meanwhile, the isotherm data obeyed the Langmuir model corresponding to (Radj)2 of 0.9993. Qmax value of MgFe2O4-20%@ACK1 was determined at 211.67 mg g-1. The proposed adsorption mechanism primarily comprises five routes as follows, (i) pore-filling, (ii) π-π interaction, (iii) electrostatic interaction, (iv) hydrogen bonding, and (v) hydrophobic interaction. MgFe2O4-20%@ACK1 adsorbent could reuse with three cycles. We recommend that MgFe2O4/ACs derived from Cynodom dactylon could be high-efficiency adsorbents for the elimination of antibiotics.

Carbonaceous adsorbents in the removal of aquaculture pollutants: A technical review of methods and mechanisms

Carbonaceous adsorbents (CAs) are becoming increasingly popular owing to their low-cost, ease of preparation, and versatility. Meanwhile, aquaculture is becoming a fundamental food industry, globally, due to a wide range of advantages such as economic and nutritional benefits, whilst protecting the depletion of natural resources. However, as with any farming, the technique is known to introduce a plethora of chemicals into the surrounding environment, including antibiotics, nutrients, fertilisers and more. Therefore, the treatment of aquaculture effluent is gaining traction to ensure the sustainable growth of the industry. Although the existing mitigation techniques are somewhat effective, they suffer from degradation of the water quality or harm to local environments/organisms. This article aims to identify the sources and impacts of various aquaculture pollutants. After which the authors will provide an environmentally friendly and novel approach to the treatment of aquaculture effluent using carbonaceous adsorbents. The article will detail discussions about the product life span, including, synthesis, activation, modification, applications in aqueous media, regeneration and End-of-Life (EoL) approaches, with a particular focus on the impacts of competitive adsorption between pollutants and environmental matrices. Some research gaps were also highlighted, such as the lack of literature applying real-world samples, the effects of competitive adsorption and the EoL applications and management for CAs.

Sono-enhanced heterogeneous Fenton catalysis: magnetic halloysite nanotube synthesis and accelerated free radical generation

Although heterogeneous Fenton catalysis has captured increasing attention compared to its homogeneous counterpart, it still confronts some inherent drawbacks in use, such as the dilemma in solid-liquid separation and greater mass transfer resistance. Driven by the acoustic cavitation effect, herein, a sono-enhanced heterogeneous Fenton catalysis process was built to overcome the above two shortcomings, by rapidly synthesizing magnetic Fenton-like catalysts and accelerating electron transfer during the catalytic reaction. The results show that, compared to the traditional chemical coprecipitation method, Fe3O4 with smaller particle size and better crystallinity grew on the surface of halloysite nanotubes (HNTs) by using the sonochemical strategy, leading to displaying the higher catalytic activity toward the degradation of methylene blue (MB, improved by ~2.5 times). In parallel, more •OH and •O2- were produced after the ultrasound was further introduced to the routine Fenton-like catalysis system, thus highly accelerating the removal of MB (improved by ~50%). Besides, benefiting from the robust chemical integration of Fe3O4 and HNTs, Fe3O4@HNTs-S had a lower iron ion leaching in use, showing superior catalytic stability. The speed, simplicity, and generality, together with the enhanced mass transfer rate, make the use of ultrasound an enabling methodology to improve the heterogeneous Fenton catalysis.

Advancements in electrochemical technologies for the removal of fluoroquinolone antibiotics in wastewater: A review

In recent times, the need to make water safer and cleaner through the elimination of recalcitrant pharmaceutical residues has been the aim of many studies. Fluoroquinolone antibiotics such as ciprofloxacin, norfloxacin, enrofloxacin, and levofloxacin are among the commonly detected pharmaceuticals in wastewater. Since the presence of these pharmaceuticals in water bodies poses serious risks to living organisms, it is vital to adopt effective wastewater treatment techniques for their complete removal. Electrochemical technologies such as photoelectrocatalysis, electro-Fenton, electrocoagulation, and electrochemical oxidation have been established as techniques capable of the complete removal of organics including pharmaceuticals from wastewater. Hence, this review presents discussions on the recent progress (literature within 2018-2022) in the applications of common electrochemical processes for the degradation of fluoroquinolone antibiotics from wastewater. The fundamentals of these processes are highlighted while the results obtained using the processes are critically discussed. Furthermore, the inherent advantages and limitations of these processes in the mineralization of fluoroquinolone antibiotics are clearly emphasized. Additionally, appropriate recommendations are made toward improving electrochemical technologies for the complete removal of these pharmaceuticals with minimal energy consumption. Therefore, this review will serve as a bedrock for future researchers concerned with wastewater treatments to make informed decisions in the selection of suitable electrochemical techniques for the removal of pharmaceuticals from wastewater.

High reusability and adsorption capacity of acid washed calcium alginate/chitosan composite hydrogel spheres in the removal of norfloxacin

Calcium alginate (CA) hydrogel spheres were widely used as adsorbents to remove organics, but their adsorption capacities and reusability to some antibiotics are unsatisfactory. In this study, calcium alginate/chitosan (CA/CTS) hydrogel spheres were prepared as precursors. Acid-washed CA/CTS (CA/CTS-M) hydrogel spheres (310.6 mg/g) behaved much better adsorption capacity of norfloxacin (NOR) than CA (69.5 mg/g) and CA/CTS (87.7 mg/g) hydrogel spheres. Astonishingly, after being reused for 15 cycles, CA/CTS-M has no loss of NOR adsorption capacity. In the original idea, acid wash was expected to remove the chitosan in CA/CTS hydrogel spheres for obtaining a larger specific surface area. Both scanning electron microscopy and Brunauer-Emmett-Teller test showed that acid wash can remove CTS from CA/CTS hydrogel spheres to increase the specific surface area. However, part of the chitosan remained in CA/CTS-M, having a role to enhance the structural stability of the material, because the acid-washed CA (about 2 mm) has a significantly smaller diameter than CA/CTS-M (about 3 mm). According to the influence of pH and density functional theory calculations, electrostatic attraction is the key driving force of NOR adsorption. Importantly, acid wash led to more negative-charged surface characterized by Zeta potential, which is the main reason of the significantly enhanced adsorption capacity of CA/CTS-M in removal of NOR. In short, CA/CTS-M hydrogel spheres are environment friendly and highly stable adsorbents with high adsorption capacity in the removal of NOR.

Remarkable synergy between sawdust biochar and attapulgite/diatomite after co-ball milling to adsorb methylene blue

Biochar has been recognized as a promising sustainable adsorbent for removing pollutants from wastewater. In this study, two natural minerals, attapulgite (ATP) and diatomite (DE) were co-ball milled with sawdust biochar (pyrolyzed at 600 °C for 2 h) at ratios of 10-40% (w/w) and examined the ability of methylene blue (MB) to be removed from aqueous solutions by them. All the mineral-biochar composites sorbed more MB than both ball milled biochar (MBC) and ball milled mineral alone, indicating there was a positive synergy in co-ball milling biochar with these minerals. The 10% (w/w) composites of ATP:BC (MABC10%) and DE:BC (MDBC10%) had the greatest MB maximum adsorption capacities (modeled by Langmuir isotherm modeling) and were 2.7 and 2.3 times that of MBC, respectively. The adsorption capacities of MABC10% and MDBA10% were 183.0 mg g^-1 and 155.0 mg g^-1 at adsorption equilibrium, respectively. These improvements can be owing to the greater content of oxygen-containing functional groups and higher cation exchange capacity of the MABC10% and MDBC10% composites. In addition, the characterization results also reveal that pore filling, π-π stacking interactions, hydrogen bonding of hydrophilic functional groups, and electrostatic adsorption of oxygen-containing functional groups also contribute prominently to the adsorption of MB. This, along with the greater MB adsorption at higher pH and ionic strengths, suggests the roles in MB adsorption was an electrostatic interaction and an ion exchange mechanism. These results demonstrate that mineral-biochar composites prepared by co-ball milling treatment were promising sorbents of ionic contaminants for environmental applications.

Bamboo-derived adsorbents for environmental remediation: A review of recent progress

The bamboo family of plants is one of the fastest-growing species in the world. As such, there is an abundance of bamboo residues available for exploitation, especially in southeast Asian, central African and south American regions. The preparation of efficient adsorbents from bamboo residues is an emerging exploitation pathway. Biochars, activated carbons or raw bamboo fibers embedded with nanoparticles, each class of materials has been shown to be highly efficient in adsorption processes. This review aims to summarize recent findings in the application of bamboo-based adsorbents in the removal of organic, inorganic, or gaseous pollutants. Therefore, this review first discusses the preparation methods and surface modification methodologies and their effects on the adsorbent elemental content and other basic properties. The following sections assess the recent progress in the adsorption of heavy metals, organics, and gaseous substances by bamboo-based adsorbents, focusing on the optimum adsorption capacities, adsorption mechanisms and the optimum-fitting kinetic models and isotherms. Finally, research gaps were identified and directions for future research are proposed.

Adsorptivity and kinetics for low concentration of gaseous formaldehyde on bamboo-based activated carbon loaded with ammonium acetate particles

The highly promising formaldehyde (HCHO)-removing materials are essential for eliminating interior pollution to safeguard the public's health with increasing indoor HCHO contamination situations being recorded on a global scale. In the paper, bamboo charcoal (BC) was activated with boric acid to prepare bamboo-based activated carbon (BAC), and then impregnated with ammonium acetate solution to successfully develop porous adsorbent with ammonium acetate particles (N/BAC), which was applied to remove low concentration of HCHO at room temperature. The adsorption performance for HCHO was systematically investigated while the surface chemical properties and microstructure of the as-prepared adsorbents were described and analyzed. The specific surface area, total pore volume and microporous volume of N/BAC sample were 240.09 m²/g, 0.27 cm³/g and 0.12 cm³/g, which increased by 42.40 m²/g, 0.15 cm³/g and 0.03 cm³/g compared with BAC sample, respectively. The specific surface area and the microporous volume, as well as the content of oxygen- and nitrogen-containing functional groups of N/BAC sample were augmented by contrast with other samples, and numerous ammonium acetate particles were present on the surface. Precisely because of this, the N/BAC sample exhibited a high removal rate of 98.89%, which was 18.38% greater than that of BAC sample. A superior correlation coefficient (0.9999) from the experimental values of the kinetics and the fitted values of the pseudo-second-order kinetic model demonstrated that the adsorption process of HCHO on N/BAC sample was physical-chemical combined adsorption. The adsorption of HCHO on N/BAC sample was investigated under different humidity, and the results showed that the adsorbent yet had excellent adsorption capacity (87.93%) under RH 75%. Moreover, the N/BAC sample was renewable, and the removal rate still reached 82.81% after five cycles of regeneration. Therefore, the as-prepared adsorbent is an effective, economical and sustainable material, and could be used to remove HCHO from real contaminated indoor air.

Anthracite based activated carbon impregnated with HMTA as an effectiveness adsorbent could significantly uptake gasoline vapors

In this study, we synthesized and employed the amine impregnated activated carbon as an efficacious adsorbent for uptaking gasoline vapor. For this regard, anthracite as activated carbon source and hexamethylenetetramine (HMTA) as amine were selected and utilized. Physiochemical characterization of made sorbents were evaluated and investigated using SEM, FESEM, BET, FTIR, XRD, zeta potential, and elemental analysis. The synthesized sorbents provided an excellent textural features as compared with the literature and other activated carbon based sorbents and impregnated with amine. Our findings also suggested that in addition to high surface area (up to 2150 m² / g), the micro- meso pores created (Vmeso / V micro = 0.79 Cm ³ / g) surface chemistry may significantly affect the gasoline sorption capacity, which here the role of mesoporous is further highlighted. V meso for amine impregnated sample and free activated carbon was 0.89 and 0.31 Cm ³ / g, respectively. According to the results, the prepared sorbents have a potential capability in uptaking gasoline vapor and with line this, we report a high sorption capacity of 572.56 mg / g. After, four cycles used the sorbent had a high durability and about 99.11% of the initial uptake was maintained. Taking together the synthesized adsorbents as an activated carbon provided an excellent and unique features and enhanced gasoline uptake, therefore its applicability in uptaking gasoline vapor can be substantially considered.

Nitrogen-doped biochar (N-doped BC) and iron/nitrogen co-doped biochar (Fe/N co-doped BC) for removal of refractory organic pollutants

The presence of refractory organic pollutants (ROPs) in the ecosystem is a serious concern because of their impact on environmental constituents as well as their known or suspected ecotoxicity and adverse health effects. According to previous studies, carbonaceous materials, such as biochar (BC), have been widely used to remove pollutants from ecosystems owing to their desirable features, such as relative stability, tunable porosity, and abundant functionalities. Nitrogen (N)-doping and iron/nitrogen (Fe/N) co-doping can tailor BC properties and provide supplementary functional groups as well as extensive active sites on the N-doped and Fe/N co-doped BC surface, which is advantageous for interaction with and removal of ROPs. This review investigates the impact of N-doped and Fe/N co-doped BC on the removal of ROPs through adsorption, activation oxidation, and catalytic reduction due to the synergistic Fe, N, and BC features that modify the physicochemical properties, surface functional groups, and persistent free radicals of BC to aid in the degradation of ROPs. Owing to the attractive properties of N-doped and Fe/N co-doped BCs for the removal of ROPs, this review focuses and evaluates previous experimental investigations on the manufacturing (including precursors and influencing parameters during manufacturing) and characterizations of N-doped and Fe/N co-doped BCs. Additionally, the effective applications and mechanisms of N-doped and Fe/N co-doped BCs in adsorption, activation oxidation, and reductive remediation of ROPs are investigated herein. Moreover, the application of N-doped and Fe/N co-doped BC for progressive environmental remediation based on their effectiveness against co-pollutants, regeneration, stability, affordability, and future research prospects are discussed.

Development and Evaluation of Cellulose/Graphene-Oxide Based Composite for Removing Phenol from Aqueous Solutions

In this study, a graphene oxide/cellulose composite (GO-cellulose) was prepared usingcellulose and graphene oxide (GO) through ultrasonication, followed by the freeze-dried method. The Brunauer-Emmett-Teller (BET) specific surface area of GO-cellulose (~6.042 m²/g) was higher compared to cellulose (1.023 m²/g).The UV-Visible spectraindicated that the prepared GO-cellulose composite removedphenol efficiently from aqueous solutions with high adsorption power. The effectiveness of the composite for phenol adsorption was examinedunder diverse conditions.The results reveal that the composite optimally improved the adsorption at pH 7 with a dose of 0.125 g/30 L in about 40 min. The adsorption process showed that in optimum conditions, 86 ± 2% of phenol was removed in 40 min with an adsorption capacity of 6.192 mg g^-1. The adsorption behavior was well fitted to the pseudo-second-order kinetic model and the Langmuir isotherms at all temperatures.The present study suggests that synthesized GO-cellulose is useful inthe removal of phenol pollutants from aqueous solutions.

Functionalized graphene oxide-zinc oxide hybrid material and its deployment for adsorptive removal of levofloxacin from aqueous media

This work reports on the synthesis of aspartic acid-functionalized graphene oxide-zinc oxide, as a functional porous material, and its potential to mitigate levofloxacin (LFXN). The adsorbent was characterized by various techniques, including ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The average crystallite size of the prepared composite was about 17.30 nm. Batch adsorption studies were carried out to elucidate the adsorption process for LFXN. Different parameters, including contact time, LFXN initial concentration, adsorbent concentration, pH, temperature, and ionic strength were studied. The mechanism and kinetics were studied by fitting the data to Freundlich and Langmuir isotherms, pseudo-first-order and pseudo-second-order kinetic models, respectively. The isotherm data was better fitted to Langmuir isotherm (R² = 0.999) as compared to the Freundlich model. The maximum adsorption capacity obtained at equilibrium was 73.15 mg/g. For kinetic studies, Pseudo first order was better fitted with R² = 0.87797, confirming the physisorption process. Thermodynamics parameters revealed that the process was exothermic and spontaneous at low temperatures. The adsorption mechanism was studied and the impregnation of LFXN in the adsorbent was confirmed by FTIR studies. This research proved that the designed GO/Asp-ZnO was a novel and promising adsorbent for the removal of LFXN with an efficiency of 95.12% at 30 mg/L LFXN by 0.6 g/L adsorbent in 24 h at pH = 7 and T = 25 °C.

Vinasse-based biochar magnetic composites: adsorptive removal of tetracycline in aqueous solutions

Highly efficient and cost-effective adsorbents for antibiotic removal are the key to mitigate pollution by industrial wastewaters. Pyrolyzing low-cost winemaking waste into biochar is a promising means for waste biomass utilization. This study assembled vinasse-derived biochar with manganese ferrite into vinasse-manganese ferrite biochar-magnetic composites (V-MFB-MCs) through simultaneous pyrolysis of waste biomass and metal (Mn and Fe) hydroxide precipitates. Batch experiments were conducted to evaluate the kinetics and isotherms of tetracycline (TC) adsorption as well as the influence of pH value, humic acid, and ionic strength. Morphological characterization showed that crystalline MnFe₂O₄ nanoparticles were impregnated within the framework of fabricated V-MFB-MCs. Superior TC adsorption capacity and fast pseudo-second-order kinetics could be achieved by the V-MFB-MCs-800 at pH 3.0. The TC adsorption onto V-MFB-MCs-800 was highly pH-dependent and controlled by the positive influence of ionic strength and humic acid. V-MFB-MCs-800 showed excellent adsorption performance in different natural water. Multiple interaction mechanisms including pore filling effect, π-π stacking interaction, and hydrogen bonding contribute to TC removal by V-MFB-MCs-800, which can be an innovative biowaste-derived material for industrial wastewater treatment.

A review of the adsorption method for norfloxacin reduction from aqueous media

Norfloxacin (NRFX) is one of a class of antibiotics known as broad-spectrum fluoroquinolone antibiotic that is frequently used to treat infectious disorders in both animals and humans. NRFX is considered an emergent pharmaceutical contaminate. This review's objective is to evaluate empirical data on NRFX's removal from aqueous medium. The environmental danger of NRFX in the aquatic environment was validated by an initial ecotoxicological study. Graphene oxide/Metal Organic Framework (MOF) based composite, followed by Magnesium oxide/Chitosan/Graphene oxide composite gave the highest NRFX adsorption capacities (Qmax) of 1114.8 and 1000 mg/g, respectively. The main adsorption mechanisms for NRFX uptake include electrostatic interactions, H-bonds, π-π interactions, electron donor-acceptor interactions, hydrophobic interactions, and pore diffusion. The adsorptive uptake of NRFX were most suitably described by Langmuir isotherm and pseudo-second order implying adsorbate-to-adsorbent electron transfer on a monolayer surface. The thermodynamics of NRFX uptake is heavily dependent on the makeup of the adsorbent, and the selection of the eluent for desorption from the solid phase is equally important. There were detected knowledge gaps in column studies and adsorbent disposal method. There's great interest in scale-up and industrial applications of research results that will aid in management of water resources for sustainability.

Adsorption Characteristics of Phosphate Based on Al-Doped Waste Ceramsite: Batch and Column Experiments

Phosphorus widely existing in rainfall and wastewater impacts the water environment. In this study, sludge, cement block, and coal fly ash were employed as ceramsite material to synthesize Al-doped waste ceramsite (Al-ceramsite) for removing phosphate (PO₄^3--P) from aqueous solutions. Batch static adsorption-desorption experiments were designed to investigate the effect of various parameters such as Al-ceramsite dosage, PO₄^3--P concentration, temperature, initial pH, coexisting ions, and desorbents on the removal of PO₄^3--P. Also, the fate of PO₄^3--P removal efficiency in actual rainwater was studied through dynamic adsorption column experiments using Al-ceramsite. Results showed that Al-ceramsite could remove PO₄^3--P efficiently under the optimum parameters as follows: Al-ceramsite dosage of 40 g/L, initial PO₄^3--P concentration of 10 mg/L, temperature of 25 °C, and pH of 5. Besides that, the Al-ceramsite could completely remove PO₄^3--P in actual rainwater, and the effluent PO₄^3--P concentration was lower than the environmental quality standards for surface water Class Ⅰ (0.02 mg/L). The adsorption characteristics of Al-ceramsite on PO₄^3--P by X-ray photoelectron spectroscopy (XPS) were further explained. As a result, ligand exchange and complexation were confirmed as the main PO₄^3--P removal mechanism of Al-ceramsite. Thus, Al-ceramsite was prepared from industrial waste and has shown excellent potential for phosphorus removal in practical applications.

Photocatalytic Degradation of Ciprofloxacin by UV Light Using N-Doped TiO2 in Suspension and Coated Forms

The presence of organic compounds such as ciprofloxacin in untreated pharmaceutical wastewater often poses a serious health risk to human and aquatic life when discharged into water bodies. One of the most effective means of removing ciprofloxacin from wastewater is photocatalytic degradation. However, the synthesis of an effective photocatalyst that can degrade the organic pollutant in the wastewater is often a challenge. Hence, this study focuses on the synthesis and application of nitrogen-doped TiO2 (N-TiO2) in suspension and coated forms for the photocatalytic degradation of ciprofloxacin in wastewater by applying UV-light irradiation. The nitrogen-doped TiO2 photocatalyst was prepared by a co-precipitation process and characterized using energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The effects of the initial concentration of the ciprofloxacin (6, 12, 18, or 30 ppm), pH (3, 5, 7, or 9), and flow rate (0.4, 0.8, 0.95, or 1.5 L/min) on the degradation of the ciprofloxacin over the N-TiO2 were investigated. The results showed that the removal efficiency of ciprofloxacin was enhanced by increasing the initial ciprofloxacin concentration, while it was decreased with the increase in the feed flow rate. The best operating conditions were obtained using an initial ciprofloxacin concentration of 30 ppm, pH of 5, and feed flow rate of 0.4 L/min. Under these operating conditions, removal efficiencies of 87.87% and 93.6% were obtained for net TiO2 and N-TiO2 of 5 wt% in suspension form, respectively, while 94.5% ciprofloxacin removal efficiency was obtained using coated 5 wt% N-TiO2 after 2 h of photocatalytic degradation. Based on the response surface optimization strategy, a quadratic model was suggested to obtain mathematical expressions to predict the ciprofloxacin removal efficiency under various studied operational parameters.

Fixed bed column performance of Al-modified biochar for the removal of sulfamethoxazole and sulfapyridine antibiotics from wastewater

In this study, biochar derived from bamboo pretreated with aluminum salt was synthesized for the removal of two sulfonamide antibiotics, sulfamethoxazole (SMX) and sulfapyridine (SPY), from wastewater. Batch sorption experiments showed that Al-modified bamboo biochar (Al-BB-600) removed both sulfonamides effectively with the maximum sorption capacity of 1200-2200 mg/kg. The sorption mechanism was mainly controlled by hydrophobic, π-π, and electrostatic interactions. Fixed bed column experiments with Al-modified biochar packed in different dosages (250, 500 and 1000 mg) and flow rates (1, 2 and 4 mL/min) showed the dosage of 1000 mg and flow rate of 1 mL/min performed the best for the removal of both SMX and SPY from wastewater. Among the breakthrough (BT) models used to evaluate the fixed bed filtration performance of Al-BB-600, the Yan model best described the BT behavior of the two sulfonamides, suggesting that the adsorption process involved multiple rate-liming factors such as mass transfer at the solid surface and diffusion Additionally, the Bed Depth Service Time (BDST) model results indicated that Al-BB-600 can be efficiently used in fixed bed column for the removal of both SMX and SPY in scaled-up continuous wastewater flow operations. Therefore, Al-modified biochar can be considered a reliable sorbent in real-world application for the removal of SMX and SPY from wastewater.

Antibiotic bioremediation by new generation biochar: Recent updates

The evolving multidrug resistance in microbes with increasing antibiotic pollution is becoming a severe global crisis. Recent developments on antibiotic remediations by biochar are promising. Advancements in biochar engineering enhanced biochar remediation efficiency to another level through developing new interactions and bonding abilities with antibiotic pollutants. Especially chemical/metal-composite modification significantly increased catalysis of biochar. The review's main focus is to underline biochar efficiency for the abatement of emerging antibiotic pollutants. Moreover, to relate feedstock, production conditions, and engineering techniques with biochar properties. Also, modification strategies are reviewed to obtain biochar or their composites before examining improved remediation potential ranging from 20 to 552 mg g^-1 for various antibiotics. Biochar offers different interactions depending on the surface functionalities e.g., π-π stacking, electrostatic, H-bonding, etc. Biochar and related composites have also been reviewed for remarkable properties e.g., photocatalysis, adsorption, and oxidation processes. Furthermore, future research directions and opportunities for biochar research are discussed.

Efficient removal of antibiotics from water resources is a public health priority: a critical assessment of the efficacy of some remediation strategies for antibiotics in water

This review discusses the fundamental principles and mechanism of antibiotic removal from water of some commonly applied treatment techniques including chlorination, ozonation, UV-irradiation, Fenton processes, photocatalysis, electrochemical-oxidation, plasma, biochar, anaerobicdigestion, activated carbon and nanomaterials. Some experimental shortfalls identified by researchers such as certain characteristics of degradation agent applied and the strategies explored to override the identified limitations are briefly discussed. Depending on interactions of a range of factors including the type of antibiotic compound, operational parameters applied such as pH, temperature and treatment time, among other factors, all reviewed techniques can eliminate or reduce the levels of antibiotic compounds in water to varying extents. Some of the reviewed techniques such as anaerobic digestion generally require longer treatment times (up to 360, 193 and 170 days, according to some studies), while others such as photocatalysis achieved degradation within short contact time (within a minimum of 30, but up to 60, 240, 300 and 1880 minutes, in some cases). For some treatment techniques such as ozonation and Fenton, it is apparent that subjecting compounds to longer treatment times may improve elimination efficiency, whereas for some other techniques such as nanotechnology, application of longer treatment time generally meant comparatively minimal elimination efficiency. Based on the findings of experimental studies summarized, it is apparent that operational parameters such as pH and treatment time, while critical, do not exert sole or primary influence on the elimination percentage(s) achieved. Elimination efficiency achieved rather seems to be due more to the force of a combination of several factors.

Enhanced Ciprofloxacin Removal from Aqueous Solution Using a Chemically Modified Biochar Derived from Bamboo Sawdust: Adsorption Process Optimization with Response Surface Methodology

Contamination of water by ciprofloxacin has become a significant concern due to its adverse health effects and growing evidence of antimicrobial-resistant gene evolution. To this end, a chemically modified bamboo biochar was prepared from bamboo sawdust to effectively remove ciprofloxacin (CIP) from an aqueous solution. Under similar adsorption conditions, the modified bamboo biochar (MBC) has an excellent CIP removal efficiency (96%) compared to unmodified bamboo biochar (UBC) efficiency (45%). Thus, MBC was used in batch adsorption experiments, and the process was optimized with the central composite design (CCD) framework of response surface methodology (RSM). Sorption process parameters such as initial CIP concentration, pH, adsorbent dose, and contact time were studied and found to have a significant effect on CIP removal. The optimal CIP removal (96%) was obtained at MBC dose (0.5 g L-1), CIP initial concentration (20 mg L-1), pH (7.5), and contact time (46 min). The adsorption kinetic data were well described by the pseudo-second-order model ( $R^2=0.999$ ), and both Langmuir ( $R^2=0.994$ ) and Freundlich ( $R^2=0.972$ ) models gave the best fit in CIP adsorption isotherm analysis. The maximum monolayer adsorption capacity of the MBC was 78.43 mg g-1 based on the Langmuir isotherm model. These results suggest that CIP adsorption was mainly controlled by chemisorption. Moreover, the CIP adsorption process was endothermic and spontaneous. Overall, MBC is a low-cost, efficient, and recyclable adsorbent for eliminating emerging contaminants such as ciprofloxacin from an aqueous solution.

Biosorptive Removal of Ethacridine Lactate from Aqueous Solutions by Saccharomyces pastorianus Residual Biomass/Calcium Alginate Composite Beads: Fixed-Bed Column Study

In this study, ethacridine lactate removal from aqueous solution using a biosorbent material based on residual microbial biomass and natural polymers in fixed-bed continuous column was investigated. Composite beads of Saccharomyces pastorianus residual biomass and calcium alginate were obtained by immobilization technique. The prepared biosorbent was characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy, and analysis of point of zero charge value. Then, laboratory-scale experiments by fixed-bed column biosorption were conducted in continuous system. To this purpose, the column bed high (5 cm; 7.5 cm), initial pollutant concentration (20 mg/L; 40 mg/L), and solution flow through the column (0.6 mL/min; 1.5 mL/min) were considered the main parameters. Recorded breakthrough curves suggest that lower flow rates, greater bed heights, and a lower concentration of ethacridine lactate led to an increased biosorption of the target compound. The biosorption dynamic was investigated by nonlinear regression analysis using the Adams–Bohart, Yoon–Nelson, Clark, and Yan mathematical models. Conclusively, our research highlights, firstly, that the obtained biosorbent material has the required properties for retaining the ethacridine lactate from aqueous solution in continuous system. Secondly, it emphasizes that the modeling approach reveals an acceptable fitting with the experimental data for the Yoon–Nelson, Clark, and Yan models.

Co-adsorption capabilities and mechanisms of bentonite enhanced sludge biochar for de-risking norfloxacin and Cu2+ contaminated water

Various bentonite-sludge biochar composites were fabricated by a sequence of loading and pyrolysis for the simultaneous removal of norfloxacin (NOR) and copper (Cu²⁺) from an aqueous solution. The morphology and characteristics of obtained composites were reflected through cation exchange capacity (CEC), BET specific surface area (S_BET), SEM, XRD, FTIR and XPS. The isothermal adsorption results showed that Sips adsorption model fitted better for the adsorption of NOR and Cu²⁺ during co-adsorption. The theoretical maximum adsorption capacity of BT:2 SB (the mass ratio of bentonite to sludge is 1:2) for NOR and Cu²⁺ was 89.36 mg g^-1 and 104.10 mg g^-1 at 25 °C in the co-adsorption system. The thermodynamic results showed the capture of NOR and Cu²⁺ was spontaneous, accompanied by an endothermic reaction with different randomness. In the co-adsorption system, the two were antagonistic to each other due to competition for the adsorption sites of hydroxyl, carboxylic acid and negatively charged provided by bentonite-sludge biochar. This study suggests that using natural mineral as a pyrolysis improver for sludge biochar can product the value-enhanced biochar for simultaneous removal of antibiotic and metal contaminants.

Efficient remediation of antibiotic pollutants from the environment by innovative biochar: current updates and prospects

The increased antibiotic consumption and their improper management led to serious antibiotic pollution and its exposure to the environment develops multidrug resistance in microbes against antibiotics. The entry rate of antibiotics to the environment is much higher than its exclusion; therefore, efficient removal is a high priority to reduce the harmful impact of antibiotics on human health and the environment. Recent developments in cost-effective and efficient biochar preparation are noticeable for their effective removal. Moreover, biochar engineering advancements enhanced biochar remediation performance several folds more than in its pristine forms. Biochar engineering provides several new interactions and bonding abilities with antibiotic pollutants to increase remediation efficiency. Especially heteroatoms-doping significantly increased catalysis of biochar. The main focus of this review is to underline the crucial role of biochar in the abatement of emerging antibiotic pollutants. A detailed analysis of both native and engineered biochar is provided in this article for antibiotic remediation. There has also been discussion of how biochar properties relate to feedstock, production conditions and manufacturing technologies, and engineering techniques. It is possible to produce biochar with different surface functionalities by varying the feedstock or by modifying the pristine biochar with different chemicals and preparing composites. Subsequently, the interaction of biochar with antibiotic pollutants was compared and reviewed. Depending on the surface functionalities of biochar, they offer different types of interactions e.g., π-π stacking, electrostatic, and H-bonding to adsorb on the biochar surface. This review demonstrates how biochar and related composites have optimized for maximum removal performance by regulating key parameters. Furthermore, future research directions and opportunities for biochar research are discussed.

Bench-Scale Fixed-Bed Column Study for the Removal of Dye-Contaminated Effluent Using Sewage-Sludge-Based Biochar

Batik industrial effluent wastewater (BIE) contains toxic dyes that, if directly channeled into receiving water bodies without proper treatment, could pollute the aquatic ecosystem and, detrimentally, affect the health of people. This study is aimed at assessing the adsorptive efficacy of a novel low-cost sewage-sludge-based biochar (SSB), in removing color from batik industrial effluent (BIE). Sewage-sludge-based biochar (SSB) was synthesized through two stages, the first is raw-material gathering and preparation. The second stage is carbonization, in a muffle furnace, at 700 °C for 60 min. To investigate the changes introduced by the preparation process, the raw sewage sludge (RS) and SSB were characterized by the Brunauer–Emmett–Teller (BET) method, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy. The surface area of biochar was found to be 117.7 m2/g. The results of FTIR showed that some functional groups, such as CO and OH, were hosted on the surface of the biochar. Continuous fixed-bed column studies were conducted, by using SSB as an adsorbent. A glass column with a diameter of 20 mm was packed with SSB, to depths of 5 cm, 8 cm, and 12 cm. The volumes of BIE passing through the column were 384 mL/d, 864 mL/d, and 1680 mL/d, at a flow rate of 16 mL/h, 36 mL/h, and 70 mL/h, respectively. The initial color concentration in the batik sample was 234 Pt-Co, and the pH was kept in the range of 3–5. The effect of varying bed depth and flow rate over time on the removal efficiency of color was analyzed. It was observed that the breakthrough time differed according to the depth of the bed and changes in the flow rates. The longest time, where breakthrough and exhausting points occurred, was recorded at the highest bed and slowest flowrate. However, the increase in flow rate and decrease in bed depth made the breakthrough curves steeper. The maximum bed capacity of 42.30 mg/g was achieved at a 16 mL/h flowrate and 12 cm bed height. Thomas and Bohart–Adams mathematical models were applied, to analyze the adsorption data and the interaction between the adsorption variables. For both models, the correlation coefficient (R2) was more than 0.9, which signifies that the experimental data are well fitted. Furthermore, the adsorption behavior is best explained by the Thomas model, as it covers the whole range of breakthrough curves.

Comparative study on characteristics and mechanism of levofloxacin adsorption on swine manure biochar

This study evaluated the relationship between pyrolysis temperature (300-900 ℃), characteristics of swine manure (SM)-derived biochar (BC), and its adsorption of levofloxacin (LEV). The surface structure and chemistry of SM-derived BCs were characterized using Brunauer-Emmett-Teller analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. According to the characteristic analysis, the surface area and graphitization degree of SM-derived BC increased as temperature rose. The highest adsorption capacity was achieved by BC-900 (158 mg/g); this level was higher than that achieved in previous studies and comparable to that of commercial activated carbons. Characterization and adsorption experiments indicated that pore-filling, π-π stacking interaction, π-π electron donor-acceptor, H-bonding, and hydrophobic interactions each played a critical role in the adsorption of LEV on SM-derived BC. Collectively, this study confirms the potential utility of SM-derived BC for the removal of antibiotics.

Effect of magnetization on the adsorptive removal of an emerging contaminant ciprofloxacin by magnetic acid activated carbon

Magnetic acid activated carbons (MAAC) were prepared from the shells of Sterculia villosa Roxb by activating the biomass and magnetizing it using the co-precipitation technique. Characterization of MAAC prior and post adsorption was performed using various microscopic and spectroscopic analytical techniques, and they verified the formation of magnetic aggregates over porous activated carbon surface. Vibrating Sample Magnetometer (VSM) analysis confirmed the superparamagnetic behaviour of the adsorbent with saturation magnetization (Ms) value of 18.2 emu/g, causing an easy and rapid recovery from the adsorption setup in the presence of an external magnetic field. Langmuir isotherm and pseudo-second-order kinetic model best fit the experimental data with theoretical Langmuir maximum adsorption capacity as 81.97 mg/g and verifying chemisorption type of adsorption process, respectively. Thermodynamic analysis verified the interaction among adsorbate and adsorbent as endothermic, spontaneous, and thermodynamically favourable. Co-existing metal cations showed a significant reduction in ciprofloxacin removal efficiency; co-existing anions, though, showed a negligible influence on the adsorption efficiency of MAAC. Recyclability studies verified that the adsorption efficiency fell from 98% in the first cycle to 43% in the fifth cycle. The Ms value fell to 7.6 emu/g (after five adsorption cycles), affecting the adsorbent's recovery. The Phyto-toxicological assessment was performed to evaluate the environmental risk to human and aquatic life using Vigna mungo seeds. MAAC proved to be an effective and magnetically separable adsorbent for removing antibiotics.