Adsorptive removal of plasticizer (dimethyl phthalate) and antibiotic (sulfamethazine) from municipal wastewater by magnetic carbon nanotubes

Evaluation of antibiofilm activity of metal oxides nanoparticles and carbon nanotubes coated styrofoam on the bacterium Jeotgalicoccus huakuii

The co-existence of metal oxide nanoparticles (MONPs), carbon-based nanomaterials and microplastics (MPs) in the natural environment are expected to be of growing global concern due to their increasing abundance and persistence in the environment worldwide. Knowledge of the interaction of the above compounds particularly under light irradiation in water remains limited. In the present study, the possible individual and combined toxic effects of MONPs, carbon nanotubes (CNTs) through styrofoam (SF) on the environmental bacterium Jeotaglicoccus huakuii were systematically investigated. The fabricated MONPs and CNTs were characterized using the following techniques: FT-IR (functional groups), XRD (crystallinity), SEM, and EDX (topological morphology). The objective of this study was to investigate and identify naturally occurring bacteria capable of mitigating and detoxifying toxic pollutants under adverse conditions. Moreover, the assessment of minimum inhibitory concentration (MIC) was made through an agar well plate method, resazurin (ELISA measurement), growth kinetics and bacterial viability were assessed employing live and dead assay and biofilm combating ability was analyzed using an antibiofilm assay. Further, the biotransformation of f-MWCNTs by J. huakuii was evaluated employing RT-PCR and SEM analysis. The results demonstrated that the toxicity of Pb3O4@f-MWCNTs was comparatively higher than the remaining Pb3O4 NPs and SF coated NPs.. Interestingly, J. huakuii showed resistance against f-MWCNTs at very high concentrations and able to utilize f-MWCNTs as a sole carbon source suggesting J. huakuii as a suitable aquatic bioremediation tool for both MONPs and CNTs transfer via MPs. The results also enhanced our understanding of the affinity of MPs towards MONPs and CNTs under extreme environmental conditions.

Preparation of novel gallic acid-based dummy-template molecularly imprinted polymer adsorbents for rapid adsorption of dibutyl phthalate from water

Phthalate esters (PAEs) are plasticizers widely used in the industry and easily released into the environment, posing a serious threat to human health. Molecularly imprinted polymers (MIPs) are important as selective adsorbents for the removal of PAEs. In this study, three kinds of mussel-inspired MIPs for the removal of PAEs were first prepared with gallic acid (GA), hexanediamine (HD), tannic acid (TA), and dopamine (DA) under mild conditions. The adsorption results showed that the MIP with low cost derived from GA and HD (GAHD-MIP) obtained the highest adsorption capacity among these materials. Furthermore, 97.43% of equilibrium capacity could be reached within the first 5 min of adsorption. Especially, the dummy template of diallyl phthalate (DAP) with low toxicity was observed to be more suitable to prepare MIPs than dibutyl phthalate (DBP), although DBP was the target of adsorption. The adsorption process was in accordance with the pseudo-second-order kinetics model. In the isotherm analysis, the adsorption behavior agreed with the Freundlich model. Additionally, the material maintained high adsorption performance after 7 cycles of regeneration tests. The GAHD-MIP adsorbents in this study, with low cost, rapid adsorption equilibrium, green raw materials, and low toxicity dummy template, provide a valuable reference for the design and development of new MIPs.

Efficacy of new generation biosorbents for the sustainable treatment of antibiotic residues and antibiotic resistance genes from polluted waste effluent

Antimicrobials are frequently used in both humans and animals for the treatment of bacterially-generated illnesses. Antibiotic usage has increased for more than 40% from last 15 years globally per day in both human populations and farm animals leading to the large-scale discharge of antibiotic residues into wastewater. Most antibiotics end up in sewer systems, either directly from industry or healthcare systems, or indirectly from humans and animals after being partially metabolized or broken down following consumption. To prevent additional antibiotic compound pollution, which eventually impacts on the spread of antibiotic resistance, it is crucial to remove antibiotic residues from wastewater. Antibiotic accumulation and antibiotic resistance genes cannot be effectively and efficiently eliminated by conventional sewage treatment plants. Because of their high energy requirements and operating costs, many of the available technologies are not feasible. However, the biosorption method, which uses low-cost biomass as the biosorbent, is an alternative technique to potentially address these problems. An extensive literature survey focusing on developments in the field was conducted using English language electronic databases, such as PubMed, Google Scholar, Pubag, Google books, and ResearchGate, to understand the relative value of the available antibiotic removal methods. The predominant techniques for eliminating antibiotic residues from wastewater were categorized and defined by example. The approaches were contrasted, and the benefits and drawbacks were highlighted. Additionally, we included a few antibiotics whose removal from aquatic environments has been the subject of extensive research. Lastly, a few representative publications were identified that provide specific information on the removal rates attained by each technique. This review provides evidence that biosorption of antibiotic residues from biological waste using natural biosorbent materials is an affordable and effective technique for eliminating antibiotic residues from wastewater.

Efficient adsorptive removal of Co2+ from aqueous solution using graphene oxide

This study aimed to utilize synthesized graphene oxide (GO) for adsorptive removal of cobalt ions and investigate the adsorption mechanism using advanced techniques such as X-ray absorption spectra (XAFS). The GO was synthesized via an improved Hummers method, resulting in high surface area (93.7 m2/g) and abundant oxygen-containing functional groups. Various characterizations, including SEM, TEM, Raman, FT-IR, TG, potentiometric titrations, and N2 sorption-desorption measurements, were employed to characterize the GO. The adsorption behavior of GO towards Co2+ was investigated, and the results showed that the adsorption process followed a pseudo-second-order kinetic model and the Langmuir model, with a maximum sorption capacity of 93.7 mg/g. The adsorption process was chemisorption and endothermic, with GO showing adsorption selectivity order of Co2+ > Sr2+ > Cs+. Based on various characterizations such as X-ray absorption near-edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), FT-IR, and XPS, the sorption mechanism of Co2+ onto GO was discussed, with the results indicating that coordination and electrostatic interaction were the primary adsorption mechanisms, with oxygen-containing functional groups playing a vital role. The first coordinating atom for Co2+ was O, and the coordination environment was similar to that of cobalt acetate and CoO. Overall, this study provides comprehensive understanding of the adsorption behavior and mechanism of Co2+ onto GO, highlighting its potential as an effective adsorbent for removing nuclides from aqueous solution.

Synergistic removal of sulfamethoxazole and dimethyl phthalate by five constructed wetland substrates

Frequent detection and joint toxicity of sulfonamides (SAs) and phthalate acid esters (PAEs) in water environment have caused serious health and safety problems that can be reduced by vertical flow constructed wetland (VFCW). However, it remains unclear what kind of substrate used in VFCW can synergistically remove SAs and PAEs. In this study, it was determined if biochar, zeolite, vermiculite, peat and sand synergistically removed sulfamethoxazole (SMX) and dimethyl phthalate (DMP) as representatives of SAs and PAEs by using batch and column experiments. The batch experiments showed that pseudo-second-order and intraparticle diffusion kinetics and Freundlich isotherm could better describe the synergistic adsorption of SMX and DMP on each substrate. SMX promoted hydrophobic interaction between DMP and each substrate so that low concentration DMP almost was adsorbed completely at neutral pH. Both neutral and alkaline pH conditions were favorable for synergistic adsorption of SMX and DMP on each substrate. The column experiments showed that removal of SMX or DMP in VFCW by substrate adsorption alone was limited with run time increasing, but SMX and DMP were effectively removed with run time increasing when loaded with simulated wastewater, SMX and DMP. The VFCW not only removed 94.7% SMX and 91.8% DMP after running 50 d, but also improved total nitrogen removal. In conclusion, these results strongly suggest that biochar, zeolite, vermiculite, peat and sand filled in VFCW can synergistically remove SMX and DMP.

Recent advances in new generation nanocomposite materials for adsorption of pharmaceuticals from aqueous environment

With rapid increase in the human population, a large amount of wastewater is generated every year. The availability of fresh water is decreasing at an alarming rate due to rapid industrialization and agricultural development. Pharmaceutical drugs which are credited for improving standards of life worldwide have emerged as major water contaminants, raising global concern about their potential risk to human health and environment. The presence of pharmaceutical compounds is detected in surface water (sea, river, lakes, etc.), groundwater, effluents from municipal, hospitals, and wastewater treatment plants, and even in drinking water. Efficient removal of pharmaceutical pollutants still remains a challenging task. Many techniques, including photodegradation, photocatalysis, oxidation, reverse osmosis, biodegradation, nanofiltration, adsorption, etc., have been used for the remediation of wastewater. Adsorption of pharmaceutical compounds on nanoadsorbents, as a low-cost and feasible technology, has gained immense popularity for wastewater treatment over the last decade. Adsorption techniques can be integrated with wastewater treatment plants to achieve efficient removal on an industrial level. Herein, we review the literature on the remediation techniques used for the pharmaceutical waste treatment using carbon nanotubes, metal oxides, nanoclay, and new-generation MXenes via adsorption. These materials show excellent adsorptive properties owing to their high surface area, low cost, high porosity, easy functionalization, and high surface reactivity. The adsorption mechanism of the nanoadsorbents and their reusability as a factor of sustainability have also been included in the review. The factors affecting the adsorption, including pH, the concentration of adsorbate, ionic strength, and adsorbate dose, have also been discussed.

Recent Advances in Carbon-Based Materials for Adsorptive and Photocatalytic Antibiotic Removal

Antibiotics have been a primary environmental concern due to their widespread dispersion, harmful bioaccumulation, and resistance to mineralization. Unfortunately, typical processes in wastewater treatment plants are insufficient for complete antibiotic removal, and their derivatives in effluent can pose a threat to human health and aquatic communities. Adsorption and photocatalysis are proven to be the most commonly used and promising tertiary treatment methods. Carbon-based materials, especially those based on graphene, carbon nanotube, biochar, and hierarchical porous carbon, have attracted much attention in antibiotic removal as green adsorbents and photocatalysts because of their availability, unique pore structures, and superior physicochemical properties. This review provides an overview of the characteristics of the four most commonly used carbonaceous materials and their applications in antibiotic removal via adsorption and photodegradation, and the preparation of carbonaceous materials and remediation properties regarding target contaminants are clarified. Meanwhile, the fundamental adsorption and photodegradation mechanisms and influencing factors are summarized. Finally, existing problems and future research needs are put forward. This work is expected to inspire subsequent research in carbon-based adsorbent and photocatalyst design, particularly for antibiotics removal.

Assisting the carbonization of biowaste with potassium formate to fabricate oxygen-doped porous biochar sorbents for removing organic pollutant from aqueous solution

In contrast to the efforts dedicated to applying porous biochars in environmental remediation, the search for green synthesis methods, which are crucial for industrialized production, is often neglected. Herein, oxygen-doped porous biochars were prepared for the first time by the assisted carbonization of hydrochar with a novel noncorrosive activator, potassium formate, and these biochars displayed a porous structure with large amounts of micropores (surface area: 1242 ∼ 1386 m² g^-1). Interestingly, the biochars contained an abundance of oxygen element (20 ∼ 26%), which formed many functional groups. Through sorption experiments, it was demonstrated that the oxygen-doped porous biochars were excellent sorbents for diethyl phthalate, and maximum sorption quantity reached 453 mg g^-1. Monolayer sorption by pore filling, hydrogen bonding, electrostatic interaction and π-π stacking was the potential mechanism. This finding indicated that potassium formate was promising as an activator to greenly convert biowaste into advanced biochars for removing organic pollutants from aqueous solutions.

Phthalates removal from wastewater by different methods - a review

Phthalate esters are commonly used as plasticizers to improve the durability and workability of polymeric materials, locating and identifying them in various contexts has become a major challenge. Because of their ubiquitous use in plastic packaging and personal care items, as well as their tendency to leach out of these materials, phthalates have been detected in a variety of aquatic situations, including surface water, groundwater, drinking water, and wastewater. Phthalate esters have been shown to affect reproductive health and physical growth by disrupting the endocrine system. As a result, developing energy-efficient and effective technologies to eliminate these harmful substances from the atmosphere has become more important and urgent. This paper examines the existing techniques for treating phthalates and degradation mechanisms, as well as knowledge gaps and future research directions. These technologies include adsorption, electrochemical, photocatalysis, membrane filtration and microbial degradation. Adsorption and photo catalysis are the most widely used techniques for phthalate removal, according to the literature survey papers.

Facile route for synthesis of Fe0/Fe3C/γ-Fe2O3 carbon composite using hydrothermal carbonization of sugarcane bagasse and its use as effective adsorbent for sulfamethoxazole removal

Non-toxic mesoporous magnetic carbon composite was synthesised from hydrothermal carbonization of sugarcane bagasse with Iron (III) nitrate nonahydrate in two steps along with thermo-chemical oxidation process using sodium hydroxide. IR spectrum exposed the presence of oxygenated functional groups and FeO whereas XRD analysis revealed the availability of Fe⁰/Fe₃C/γ-Fe₂O₃ at varying intensities. SEM analysis showed the spherical shaped carbon is well encapsulated with iron particles. Textural studies showed that after thermo-chemical activation intensified the surface area on composites to about 491.474 m² g^-1 thereby, promoting improved porosity on the carbon matrix. The fabricated composite showed magnetization of 32.84 emu g^-1 and SMX adsorption capacity as 169.49 mg g^-1. Kinetics and isotherm studies revealed that removal of SMX fitted well in Pseudo-second order and Langmuir models. The mode of interaction of SMX on magnetic carbon composites with respect to different pH was studied showing that π-π electron donor interaction (EDA), hydrophobic interaction, charge assisted hydrogen bond formation were responsible for SMX removal. The selectivity nature of magnetic composite with respect to SMX was studied in the presence of multiple pollutant. Use of magnetic carbon helps in industrialising the material to high level due to their unique property in separation and recycling. Application of hydrothermal carbonization is found to be applicable for wet solid substance thereby evolving structural carbon compound.

A novel CNTs-Fe3O4 synthetized via a ball-milling strategy as efficient fenton-like catalyst for degradation of sulfonamides

A novel composite (CNTs-Fe₃O₄) was synthesized by a ball-milling strategy and characterized by BET, SEM, FTIR, XRD and VSM. The as-fabricated CNTs-Fe₃O₄ was used to remove six sulfonamides by a Fenton degradation process, including sulfanilamide (SAM), sulfamerazine (SMR), sulfadimethoxine (SMX), sulfadiazine (SDZ), sulfamethazine (SMT) and sulfametoxydiazine (SMD). The degradation behaviors of six sulfonamides in CNTs-Fe₃O₄/H₂O₂ system and the relationship between molecular structure of sulfonamides and their degradation behaviors were investigated systematically. Batch experimental results showed that the as-fabricated CNTs-Fe₃O₄ had excellent Fenton catalytic activity for the degradation of sulfonamides due to its unique porous structure and the good combination mode of CNTs with Fe₃O₄ particles. The first-order kinetic mode could better describe the degradation behaviors of six sulfonamides in CNTs-Fe₃O₄/H₂O₂ system, and the degradation rate constant could be ordered as: SAM < SMT < SDZ < SMR < SMD < SMX. The quantitative relationship between the Mulliken charge of sulfonamides (x) and their degradation rate constant (y) in CNTs-Fe₃O₄/H₂O₂ system could be described as: y = - 28.719x + 15.67 (R² = 0.957). Finally, the possible synthesis mechanisms of CNTs-Fe₃O₄ and the degradation mechanisms of sulfonamides in CNTs-Fe₃O₄/H₂O₂ system was proposed.

The Potential for PE Microplastics to Affect the Removal of Carbamazepine Medical Pollutants from Aqueous Environments by Multiwalled Carbon Nanotubes

Microplastics are ubiquitous in aquatic environments and interact with other kinds of pollutants, which affects the migration, transformation, and fate of those other pollutants. In this study, we employ carbamazepine (CBZ) as the contaminant to study the influence of polyethylene (PE) microplastics on the adsorption of CBZ pollutants by multiwalled carbon nanotubes (MCNTs) in aqueous solution. The adsorption capacity of CBZ by MCNTs in the presence of PE microplastics was obviously lower than that by MCNTs alone. The influencing factors, including the dose of microplastics, pH, and CBZ solution concentration, on the adsorption of CBZ by MCNTs and MCNTs-PE were thoroughly investigated. The adsorption rate of CBZ by MCNTs decreased from 97.4% to 90.6% as the PE microplastics dose increased from 2 g/L to 20 g/L. This decrease occurred because the MCNTs were coated on the surface of the PE microplastics, which further decreased the effective adsorption area of the MCNTs. This research provides a framework for revealing the effect of microplastics on the adsorption of pollutants by carbon materials in aqueous environments.

Activated Porous Carbon Derived from Tea and Plane Tree Leaves Biomass for the Removal of Pharmaceutical Compounds from Wastewaters

The aim of the present study is the synthesis of activated carbon (AC) from different agricultural wastes such as tea and plane tree leaves in order to use them for the removal of pramipexole dihydrochloride (PRM) from aqueous solutions. Two different carbonization and synthetic activation protocols were followed, with the herein-proposed ultrasound-assisted two-step protocol leading to better-performing carbon, especially for the tea-leaf-derived material (TEA(char)-AC). Physicochemical characterizations were performed by Fourier-transform infrared spectroscopy (FTIR), N₂ physisorption, and scanning electron microscopy (SEM). TEA(char)-AC presented the highest surface area (1151 m²/g) and volume of micro and small mesopores. Maximum capacity was found at 112 mg/g for TEA(char)-AC at an optimum pH equal to 3, with the Langmuir isotherm model presenting a better fitting. The removal efficiency of TEA(char)-AC is higher than other biomass-derived carbons and closer to benchmark commercial carbons.