Adsorption characteristics of beta-lactam cefixime onto nanosilica fabricated from rice HUSK with surface modification by polyelectrolyte

Recent advances and future trends in metal oxide photocatalysts for removal of pharmaceutical pollutants from wastewater: a comprehensive review

The rapid and widespread increase in pharmaceutical micropollutants (PMPs) poses a significant and immediate threat to ecosystems and human health globally. With the demand for clean water becoming increasingly critical, particularly amid escalating global water scarcity challenges, there is an urgent need for innovative approaches. Among the potential solutions, metal oxide photocatalysts such as titanium dioxide-based (TiB) and zinc oxide-based (ZnB) have garnered attention due to their cost-effectiveness, efficient photodegradation capabilities, and inherent stability. This comprehensive review explores recent advancements in the application of TiB and ZnB for the removal of PMPs from wastewater. It examines the multifaceted impacts of PMPs on environmental and public health, evaluates various techniques for their removal, and assesses design strategies aimed at maximizing the photocatalytic efficiency of TiB and ZnB. The mechanisms responsible for the photocatalytic degradation of pharmaceutical micropollutants using TiB and ZnB photocatalysts are comprehensively detailed. Finally, the review outlines the prospects and challenges associated with the use of TiB and ZnB photocatalysts for the removal of PMPs from wastewater. It emphasizes their potential to effectively mitigate PMP contaminants and make substantial contributions to sustainable water management practices in the face of escalating environmental and public health concerns.

Comparison of modeling, optimization, and prediction of important parameters in the adsorption of cefixime onto sol-gel derived carbon aerogel and modified with nickel using ANN, RSM, GA, and SOLVER methods

Today, the main goal of many researchers is the use of high-performance, economically and industrially justified materials, as well as recyclable materials in removing organic and dangerous pollutants. For this purpose, sol-gel derived carbon aerogel modified with nickel (SGCAN) was used to remove Cefixime from aqueous solutions. The influence of important parameters in the cefixime adsorption onto SGCAN was modeled and optimized using artificial neural network (ANN), response surface methodology (RSM), genetic algorithm (GA), and SOLVER methods. R software was applied for this purpose. The design range of the runs for a time was in the range of 5 min-70 min, concentration in the range of 5 mg L-1 to 40 mg L-1, amount of adsorbent in the range of 0.05 g L-1 to 0.15 g L-1, and pH in the range of 2.0-11. The results showed that the ANN model due to lower Mean Squared Error (MSE), Sum of Squared Errors (SSE), and Root Mean Squared Error (RMSE) values and also higher R2 is a superior model than RSM. Also, due to the superiority of ANN over the RSM model, the optimum results were calculated based on GA. Based on GA, the highest Cefixime adsorption onto SGCAN was obtained in pH, 5.98; reaction time, 58.15 min; initial Cefixime concentration, 15.26 mg L-1; and adsorbent dosage, 0.11 g L-1. The maximum adsorption capacity of Cefixime onto SGCAN was determined to be 52 mg g-1. It was found the pseudo-second-order model has a better fit with the presented data.

Biosynthesis approach of copper nanoparticles, physicochemical characterization, cefixime wastewater treatment, and antibacterial activities

The aim of this paper is the green synthesis of copper nanoparticles (Cu NPs) via Quinoa seed extract. X-ray diffraction (XRD) results confirmed the production of the pure crystalline face center cubic system of the Cu NPs with an average crystallite size of 8.41 nm. Infrared spectroscopy (FT-IR) analysis confirmed the capping and stabilization of the Cu NPs bioreduction process. UV visible spectroscopy (UV-Vis). surface plasmon resonance revealed the absorption peak at 324 nm with an energy bandgap of 3.47 eV. Electrical conductivity was conducted assuring the semiconductor nature of the biosynthesized Cu NPs. Morphological analysis was investigated confirming the nano-characteristic properties of the Cu NPs as polycrystalline cubic agglomerated shapes in scanning electron microscopy (SEM) analysis. Transmission electron microscopy (TEM) analysis also was used to assess the cubic shapes at a particle size of 15.1 ± 8.3 nm and a crystallinity index about equal to 2.0. Energy dispersive spectroscopy (EDX) was conducted to investigate the elemental composition of the Cu NPs. As a potential utility of the biosynthesized Cu NPs as nano adsorbents to the removal of the Cefixime (Xim) from the pharmaceutical wastewater; adsorption studies and process parameters were being investigated. The following strategic methodology for maximum Xim removal was conducted to be solution pH 4, Cu NPs dosage 30 mg, Xim concentration 100 mg/L, and absolute temperature 313 K. The maximum monolayer adsorption capacity was 122.9 mg/g according to the Langmuir isothermal model, and the kinetic mechanism was pseudo-second-order. Thermodynamic parameters also were derived as spontaneous chemisorption endothermic processes. Antibacterial activity of the Xim and Xim@Cu NPs was investigated confirming they are highly potent against each Gram-negative and Gram-positive bacterium.

Treatment of tannery wastewater by silica nanoparticles produced from rice husk ash via a green route

Rice husk, which is one of the abundant agricultural biomasses in nature, contains organic and inorganic elements, spastically silica. This waste is frequently managed via incineration, resulting in the contamination of soil, water, and air due to emission of greenhouse gasses and ash. In the present investigation, the potential of silica powder obtained from the rice husk was demonstrated by the removal of Cr(III) from the tannery wastewater. Different combinations of sulfuric, hydrochloric, and acetic acids were used as precipitation agents to produce silica through the conventional and ultrasound-assisted techniques. The mesoporous silica fabricated via the sonication indicated the larger pores, 22 nm, compared to that produced via the conventional method by the employment of sulfuric acid, 10 nm, leading to achieve an adsorption capacity ~385 mg g^-1. Although both of applied techniques could develop mesoporous structure, precipitation should be carried out under sonication in the presence of acetic acid for the green production of silica with the appropriate adsorption performance. The conversion of rice husk into silica powder with specific surface area ~62 m² g^-1 could prevent the environmental pollution due to employment of acetic acid in the precipitation stage.

Process optimization for enhanced carbon capture and cyclic stability using adsorbents derived from coal fly ash

Zeolites and metal-organic frameworks (MOFs) are popular adsorbents when it comes to capturing CO₂ from the gaseous feed stream. In this study, a hybrid of zeolite and ZIF-8 adsorbent was synthesized from coal fly ash via fusion-hydrothermal process and then in-situ aqueous ZIF-8 synthesis technique. This technique of in-situ synthesis is highly cost-effective as it is done at room temperature. The hybrid adsorbent showed an enhanced microporosity as compared to zeolites synthesized from coal fly ash due to the in-situ synthesis of ZIF-8 upon coal fly ash zeolite. It was designated as CFAZ/ZIF-8. At 298 K, a maximum CO₂ uptake value of 2.83 mmol/g was observed with a constant decrease with an increase in temperature. BET surface area value of 426 m²/g was obtained for this adsorbent. Kinetics fit for the best uptake value was performed with the Avrami model kinetics, describing the adsorption well at an R² value of 0.997 for the fit. The adsorbent also showed impressive cyclic stability after five cycles of carbonation and decarbonation. The cyclic stability studies show that the as-synthesized hybrid adsorbent shows promise in CO₂ uptake studies.

Synthesis and Characterization of Novel Core-Shell ZnO@SiO2 Nanoparticles and Application in Antibiotic and Bacteria Removal

A novel core-shell nanomaterial, ZnO@SiO₂, based on rice husk for antibiotic and bacteria removal, was successfully fabricated. The ZnO@SiO₂ nanoparticles were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET) method, diffuse reflectance ultraviolet-vis (DR-UV-vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and ζ-potential measurements. β-Lactam antibiotic amoxicillin (AMX) was removed using ZnO@SiO₂ nanoparticles with an efficiency greater than 90%, while Escherichia coli removal was higher than 91%. The optimum effective conditions for AMX removal using ZnO@SiO₂, including solution pH, adsorption time, and ZnO@SiO₂ dosage, were 8, 90 min, and 25 mg/mL, respectively. The maximum adsorption capacity reached 52.1 mg/g, much higher than those for other adsorbents. Adsorption isotherms of AMX on ZnO@SiO₂ were more in accordance with the Freundlich model than the Langmuir model. The electrostatic attraction between negative species of AMX and the positively charged ZnO@SiO₂ surface induced adsorption, while the removal of E. coli was governed by both electrostatic and hydrophobic interactions. Our study demonstrates that ZnO@SiO₂ based on rice husk is a useful core-shell nanomaterial for antibiotic and bacteria removal from water.

Highly adsorptive protein inorganic nanohybrid of Moringa seeds protein and rice husk nanosilica for effective adsorption of pharmaceutical contaminants

The present study aims to investigate adsorption characteristics and mechanisms of Moringa (MO) seeds protein on nanosilica rice husk and their applications in removal of pharmaceutical residues including the fluoroquinolone antibiotic levofloxacin (LFX) and the nonsteroidal anti-inflammatory drug diclofenac (DCF) in aquatic environment. Molecular weight of MO protein was determined by gel-permeation chromatography (GPC) method while its amino acids were quantified by high performance liquid chromatography (HPLC). The number-(M_n) and weight-average molecular weights (M_w) of MO protein were 1.53 × 10⁴ and 1.61 × 10⁴ g/mol, respectively. Different effective conditions on adsorption protein on nanosilica including contact time, pH, adsorbent dosage, and ionic strength were systematically optimized and found to be 180 min, 10, 10 mg/mL and 1 mM KCl, respectively. The surface charge change by zeta potential, surface modification by Fourier-transform infrared spectroscopy (FT-IR) and adsorption isotherms demonstrated that protein adsorption on nanosilica was governed by both electrostatic and non-electrostatic interactions. Application of protein functionalized nanosilica (ProFNS) in LFX and DCF removal were also thoroughly studied. The selected conditions for LFX and DCF removal using ProFNS were 1 mM KCl for both LFX and DCF; pH 8 and pH 6; contact time 90 and 120 min, and adsorption dosage 10 and 5 mg/ml for LFX and DCF, respectively. Adsorption isotherms of protein on nanosilica as well as LFX and DCF onto ProFNS at different ionic strengths were reasonably fitted by the two-step model while a pseudo-second-order model could fit adsorption kinetic well. The removal of LFX and DCF using ProFNS significantly increased from 51.51% to 87.35%, and 7.97%-50.02%, respectively. High adsorption capacities of 75.75 mg/g for LFX and 59.52 mg/g for DCF, indicate that ProFNS is a great performance for pharmaceutical residues removal in water environment.

Sulfide-Doped Magnetic Carbon Nanotubes Developed as Adsorbent for Uptake of Tetracycline and Cefixime from Wastewater

In this study, a magnetic solid-phase extraction method was developed based on multi-wall carbon nanotubes decorated by magnetic nanoparticles (Fe₃O₄) and cadmium sulfide nanoparticles (Fe₃O₄@MWCNT-CdS) for trace extraction of cefixime and tetracycline antibiotics from urine and drug company wastewater. The adsorbent features were characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and energy dispersive X-ray analysis (EDX). Various effective parameters on the sorption and desorption cycle, such as sorption time, the mass of adsorbent, pH, salt addition, and material ratio, were investigated and optimized. The data were evaluated using isotherm models, and experimental data were well-fitted to both Langmuir (R² = 0.975) and Freundlich (R² = 0.985) models. Moreover, kinetic of reaction was agreement with pseudo-second-order (R² = 0.999) as compared pseudo-first-order (R² = 0.760). The maximum adsorption capacity for tetracycline and cefixime was achieved at 116.27 and 105.26 mg·g^-1, respectively. Hence, the prepared adsorbent can be used as an alternative material for enhanced determination of pharmaceutical substances in biological fluids.

Mango Seed-Derived Hybrid Composites and Sodium Alginate Beads for the Efficient Uptake of 2,4,6-Trichlorophenol from Simulated Wastewater

In this study, mango seed shell (MS)-based hybrid composite and composite beads (FeCl3-NaBH4/MS and Na-Alginate/MS) were designed. Batch and column experimental analyses were performed for the uptake of 2,4,6-trichlorophenol (2,4,6-TCP) from wastewater. The physicochemical characteristics of both composites were also examined. From the batch adsorption experiments, the best adsorption capacities of 28.77 mg/g and 27.42 mg/g were observed in basic media (pH 9–10) at 308 K for FeCl3-NaBH4/MS and 333 K for Na-Alginate/MS with 25 mg/L of 2,4,6-TCP concentration for 120 min. The rate of reaction was satisfactorily followed by the pseudo-second-order kinetics. Equilibrium models revealed that the mechanism of reaction followed the Langmuir isotherm. The thermodynamic study also indicated that the nature of the reaction was exothermic and spontaneous with both adsorbents. Desorption experiments were also carried out to investigate the reliability and reusability of the composites. Furthermore, the efficiency of the adsorbents was checked in the presence of different electrolytes and heavy metals. From the batch experimental study, the FeCl3-NaBH4/MS composite proved to be the best adsorbent for the removal of the 2,4,6-TCP pollutant, hence it is further selected for fixed-bed column experimentation. The column study data were analyzed using the BDST and Thomas models and the as-selected FeCl3-NaBH4/MS hybrid composites showed satisfactory results for the fixed-bed adsorption of the 2,4,6-TPC contaminants.

Removal of beta-lactam antibiotic in water environment by adsorption technique using cationic surfactant functionalized nanosilica rice husk

This study aims to investigate the adsorption characteristics of cationic surfactant, cetyltrimethylamonium bromide (CTAB) onto negatively nanosilica rice husk surface and the application for antibiotic treatment in water environment. Adsorption of CTAB onto nanosilica increased with an increase of solution pH, due to an enhancement of the electrostatic attraction between cationic methylamomethylamonium groups and negatively charged nanosilica surface enhanced at higher pH. Adsorption of CTAB decreased with a decrease of ionic strength while a common intersection point (CIP) was observed for adsorption isotherm at different ionic strengths, suggesting that hydrophobic interactions between alkyl chains in CTAB molecules significantly induced adsorption and admicelles with bilayer formation were dominant than monolayer of hemimicelles. The CTAB functionalized nanosilica (CFNS) was applied for removal of beta-lactam amoxicillin (AMX). The best conditions for AMX treatment using CFNS were selected as pH 10, contact time 60 min and CFNS dosage 10 mg/mL. Removal efficiency of AMX using CFNS reached to 100% under optimum conditions while it was only 25.01% using nanosilica without CTAB. The maximum AMX adsorption capacity using CFNS of about 25 mg/g was much higher than other adsorbents. The effects of different organics such as humic acid, anionic surfactant, and other antibiotics on AMX removal using CFNS were also studied. A two-step model can fit CTAB uptake isotherms onto nanosilica and AMX onto CFNS well at different KCl concentrations. Based on the desorption of CTAB with AMX adsorption as well as adsorption isotherms, the change in surface charge and functional vibration groups after adsorption, we indicate that AMX adsorption onto CFNS was mainly controlled by electrostatic interaction. We reveal that CFNS is an excellent adsorbent for antibiotic treatment from aqueous solution.

Recent progress in the applications of silica-based nanoparticles

Functionalized silica nanoparticles (SiO2 NPs) have attracted great attention due to their promising distinctive, versatile, and privileged physiochemical characteristics. These enhanced properties make this type of functionalized nanoparticles particularly appropriate for different applications. A lack of reviews that summarizes the fabrications of such nanomaterials and their different applications in the same work has been observed in the literature. Therefore, in this work, we will discuss the recent signs of progress in the fabrication of functionalized silica nanoparticles and their attractive applications that have been extensively highlighted (advanced catalysis, drug-delivery, biomedical applications, environmental remediation applications, and wastewater treatment). These applications have been selected for demonstrating the role of the surface modification step on the various properties of the silica surface. In addition, the current challenges in the applications of functionalized silica nanoparticles and corresponding strategies to discuss these issues and future perspectives for additional improvement have been addressed.

Biochar/Mg-Al spinel carboxymethyl cellulose-La hydrogels with cationic polymeric layers for selective phosphate capture

Recently, biochar-related phosphate sorbents have been extensively investigated and achieved significant progress; however, there is still much room for enhancement on capturing performance and recovery of powdery ones after sorption. Herein, a new kind of adsorbent, in which biochar/Mg-Al spinel encapsulated in carboxymethyl cellulose-La hydrogels with cationic polymeric layers, was fabricated, aiming for integrating multi-advantages of each component for enhanced phosphate capture. Batch static experiments were correlated to the phosphate adsorption performance of the adsorbent. The maximum phosphate adsorption capacity of the adsorbent was 89.65 mg P/g at pH = 3. The Langmuir isotherm model and the pseudo-second-order kinetic model fitted well with the adsorption behavior of the adsorbent. More importantly, this composite adsorbent that integrated with biochar, Mg-Al spinel, cationic polymeric components exhibited favorable selectivity over coexisting anions (Cl^-, SO₄^2-, HCO₃^- and NO₃^-) and performed good reusability after five consecutive cycles. By virtue of the bead-like feature, fixed-bed column experiments demonstrated that the Thomas model fitted the breakthrough curves well under varied experimental conditions. The adsorption mechanism of phosphate on the designed composite adsorbent with multi-components could be described as the electrostatic attraction, ligand exchange and inner-sphere complexation, which might account for the efficient phosphate capturing performance.

Preparation of resin-based composites containing Ce and cationic polymers with abundant promotional affinity sites for phosphate capture

A new type of composite, D301-Ce+, for efficient and selective phosphate removal.

Synthesizing and Evaluating the Photocatalytic and Antibacterial Ability of TiO2/SiO2 Nanocomposite for Silicate Coating

The TiO₂/SiO₂ nanocomposite has been synthesized by a sol-gel method and investigated the effect of the SiO₂ content (0, 5, 10, 15, 20, and 50%) on the rutile-to-anatase phase transition of TiO₂ NPs. In order to increase the photocatalytic efficiency of the nanocomposite and decrease the price of material, the TiO₂/SiO₂ Nc with content SiO₂ of 15% sample is chosen for preparing silicate coating. The efficiency of photocatalytic MB and antibacterial ability in the air of W silicate coating (adding TiO₂/SiO₂ Nc (15%)) achieve almost 100% for 60 h and 94.35% for 3 h, respectively. While the efficiency of photocatalytic MB and antibacterial ability of WO silicate coating (adding commercial TiO₂/SiO₂) is about 25–30% for 60 h and 6.02% for 3 h, respectively. The presence of TiO₂/SiO₂ Nc (15%) with a larger surface area in W silicate coating can provide increased centers for absorption, photocatalytic reaction, and the contact between sample and bacteria lead to enhance the photocatalytic and antibacterial ability of W silicate coating.

Eco-friendly rice husk pre-treatment for preparing biogenic silica: Gluconic acid and citric acid comparative study

Carboxylic acid leaching has been established eco-friendly pre-treatment method for producing biogenic silica (BSi) from rice husk. The most urgent issue is for carboxylic acid to promote new readily biodegradable acids and enhance carboxylic acid sustainability in BSi preparation. This research investigates gluconic acid (GA) applicability for biogenic silica preparation from rice husk compared with citric acid (CA). The results demonstrated that GA was preferable to CA on BSi recovery with 89.91% efficiency. Although GA leaching promoted slightly higher silica loss, the primary metal alkali impurities, such as K₂O, Na₂O, and Al₂O_3, were effectively removed at 92-93%, 89-93%, 95-97%, respectively. The combination effect of silica loss and high removal impurities resulted in lower rice husk thermal decomposition activation energy. The characteristics of BSi prepared by GA leaching were comparable with CA leaching, mainly mesoporous with 114.06 m²/g of specific surface area and 0.23 cm³/g of the pore volume. In addition, GA leaching was environmentally better than CA leaching, indicated by minor contribution to all environmental impact indices. The findings suggested that GA could be a potential replacement for prevalent carboxylic acids in BSi preparation.

Effective removal of doxycycline from aqueous solution using CuO nanoparticles decorated poly(2-acrylamido-2-methyl-1-propanesulfonic acid)/chitosan

The primary focus of the present study was to synthesize CuO nanoparticles decorated poly(2-acrylamido-2-methyl-1-propanesulfonic acid)/chitosan to explore its potential for uptake of doxycycline (DXN) from water. The composite material was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction and thermogravimetric analysis-differential thermal analysis. Central composite design under response surface methodology was opted to optimize the process variables (pH, adsorbent dosage, contact time and initial concentration of DXN) for obtaining the highest removal efficiency. The removal of DXN reached 98.84% at 303 K under the optimum conditions of pH 7.0, equilibrating time of 70 min, adsorbent dose of 20 mg/25 mL and initial concentration of 50 mg L-1. The Langmuir isotherm and pseudo-second-order kinetic models fitted best with the experimental data. The values of ΔG° (- 29.159 to - 31.997 kJ mol-1), ΔH° (56.768 kJ mol-1) and ΔS° (283.382 J mol-1 K-1) demonstrated the spontaneous and endothermic nature of adsorption process. The adsorption/desorption study revealed the reusability of the prepared composite material for DXN uptake up to six cycles.

Synthesis and surface modification of magnetic Fe3O4@SiO2 core-shell nanoparticles and its application in uptake of scandium (III) ions from aqueous media

The main objective of this work is to produce an eco-friendly and economically nano-adsorbent which can separate scandium metal ions Sc from a model aqueous phase prior to applying these adsorbents in industrial filed. The magnetic core-shell structure Fe3O4@SiO2 nanoparticles were synthesized by modified Stöber method and functionalized with (3-aminopropyl) triethoxysilane APTES as a coupling agent and ethylenediaminetetraacetic acid (EDTA) as a ligand. Magnetic nano support adsorbents exhibit many attractive opportunities due to their easy removal and possibility of reusing. The ligand grafting was chemically robust and does not appreciably influence the morphology or the structure of the substrate. To evaluate the potential, the prepared hybrid nanoparticles were used as nano-adsorbent for Sc ions from model aqueous solutions due to the fact that rare earth elements (REEs) have a strong affinity for oxygen and nitrogen donors. The iron oxide nanoparticles were prepared by co-precipitation method at pH 10 and pH 11 to get the best morphology and nanoscale dimensions of iron oxide magnetic nanoparticles. The particle size, morphology, specific surface area, and surface modification were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), and X-ray powder diffraction (XRD). The results showed that the Fe3O4 nanoparticles with average particle size of 15 ± 3 nm were successfully synthesized at pH 11, and 25 °C. Moreover, the prepared Fe3O4 nanoparticles were coated with amorphous SiO2 and functionalized with amino and carboxyl groups. The adsorption study conditions of Sc are as follows: the initial concentrations of the Sc model solution varied 10-50 mg/L, 20 mL volume, 20-80 mg of the Fe3O4@SiO2-COO adsorbent, pH range of 1-5, and 5 h contact time at 25 °C temperature. The adsorption equilibrium was represented with Langmuir, Freundlich, and Temkin isotherm models. Langmuir model was found to have the correlation coefficient value in good agreement with experimental results. However, the adsorption process followed pseudo-second-order kinetics.

Adsorptive Removal of Anionic Azo Dye New Coccine Using Silica and Silica-gel with Surface Modification by Polycation

In the present work, adsorption of anionic azo dye, new coccine (NCC) on silica and silica-gel in an aquatic environment was discovered. Effective conditions such as adsorption time, pH, the influence of dosage on NCC adsorption using strong polycation, poly-diallyl-dimethylammonium chloride (PDADMAC) modified silica (PMS) and PDADMAC modified silica-gel (PMSG) were systematically studied. The removal of NCC using PMS and PMSG were much higher than that using raw silica and silica-gel without PDADMAC in all pH ranges from 3 to 10. The adsorption of NCC onto PMS and PMSG was achieved maxima at the same conditions of contact time 30 min, pH 6. The optimum adsorbent dosages of PMS and PMSG for NCC removal were 10 and 20 mg·mL-1, respectively. Experimental results of NCC adsorption isotherms onto PMS and PMSG at different ionic strength were fitted by Langmuir and Freundlich models. The NCC removal efficiencies using PMS and PMSG were higher than 87%, indicating that PMS and PMSG are novel and reusable adsorbents for removal of anionic dye. Based on adsorption isotherms, and surface group changes after PDADMAC modification and NCC adsorption examined by Fourier transform infrared spectroscopy (FTIR), we demonstrate that electrostatic interaction between positively charged adsorbents' surfaces and negative sulfonic groups of NCC are the main driving force for anionic azo dye adsorption onto PMS and PMGS adsorbents.

Detailed characterization, antibiotic resistance and seasonal variation of hospital wastewater

This study investigates the presence of the different classes of micro-pollutants such as pharmaceutical active compounds (PhACs) (20 antibiotics, 8 analgesics and anti-inflammatories, 5 cytostatic agents, 7 β-blockers, 4 lipid regulators, 13 psychiatrics, 1 antidiabetic, 1 receptor antagonist, 1 local anaesthetic, 1 antihypertensive and their 5 metabolites), hormones (8 compounds), X-ray contrast agents (6 compounds), benzotriazoles (3 compounds) and pesticides (6 compounds), and antibiotic resistance in hospital wastewater (HWW) of a medical faculty in Istanbul, Turkey. In addition, the seasonal variations of the selected PhACs and X-ray contrast agents and antibiotic resistance were evaluated for 2 years in a total of eight samples. In the PhACs, sulfamethoxazole and its metabolite (4 N-acethyl-sulfamethoxazole) in the antibiotic group and paracetamol in the analgesic and anti-inflammatory group were found at 100% of frequency and the highest concentrations as 35, 43 and 210 μg/L, respectively. The mean concentrations of psychiatric compounds were found less than 0.25 μg/L except carbamazepine (1.36 μg/L). Bisphenol A in hormone group had the highest concentration up to 14 μg/L. In the hormone group compounds, 17-α-Ethinylestradiol and 17-β-Estradiol were detected at lower mean concentrations of 0.2 and 0.05 μg/L, respectively. 1H-benzotriazole had the highest concentration with the mean concentration of 24.8 μg/L in benzotriazole group compounds. The compounds in X-ray contrast agents group were noted as compounds detected at the highest concentration in HWW up to 3000 μg/L. Antibiotic resistance against azithromycin, clindamycin and trimethoprim-sulfamethoxazole antibiotics was observed around 50% in the winter period. The seasonal variation was detected for the most of the investigated PhACs, especially in antibiotic group which was in line with those significant differences in antibiotic resistance rates in the studied antibiotics between winter and summer seasons.

Preparation of Sodium Lignosulfonate/Chitosan Adsorbent and Application of Pb2+ Treatment in Water

Industrial wastewater has brought huge disasters to water resources and soil and has seriously affected the growth of animals and plants. There is an urgent need for a green and efficient adsorbent to solve the problem of water pollution. Sodium lignosulfonate and chitosan undergo free radical polymerization to form a lignin/chitosan adsorbent, which is used to treat Pb2+ in water pollution. An orthogonal experiment was used to optimize the content of sodium lignosulfonate, chitosan, cross-linking agent and initiator to obtain the adsorbent with the best adsorption performance. The adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal analysis and zeta potentiometry. The influence of different conditions on the adsorption of heavy metal ions by lignosulfonate/chitosan adsorbent was explored, and a kinetic and isotherm model was established. The results showed that the adsorption capacity of Pb2+ was 345 mg g−1 when the adsorbent was 0.01 g, the concentration of heavy metal ions was 100 mg L−1 and pH was 7. The adsorption process of lignosulfonate/chitosan is a kind of spontaneous adsorption mode, which is mainly composed of electrostatic adsorption and chemical adsorption.

Synthesis and Characterization of Novel Hybridized CeO2@SiO2 Nanoparticles Based on Rice Husk and Their Application in Antibiotic Removal

This work aims to synthesize a core-shell material of CeO₂@SiO₂ based on rice husk as a novel hybridized adsorbent for antibiotic removal. The phase structures of CeO₂@SiO₂ and CeO₂ nanoparticles that were fabricated by a simple procedure were examined by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FT-IR) spectroscopy, while their interfacial characterizations were performed by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), the Brunauer-Emmett-Teller (BET) method, and ζ-potential measurements. The removal efficiency of the antibiotic amoxicillin (AMX) using CeO₂@SiO₂ nanoparticles was much greater than that using SiO₂ and CeO₂ materials in solutions of different pH values. The optimum conditions for AMX removal using CeO₂@SiO₂ including contact time and adsorbent dosage were 120 min and 5 mg/mL, respectively. The maximum AMX removal using CeO₂@SiO₂ reached 100% and the adsorption capacity was 12.5 mg/g. Adsorption isotherms of AMX onto CeO₂@SiO₂ were fitted by Langmuir, Freundlich, and two-step adsorption models, while the adsorption kinetics of AMX achieved a better fit by the pseudo-second-order model than the pseudo-first-order model. The electrostatic and nonelectrostatic interactions between the zwitterionic form of AMX and the positively charged CeO₂@SiO₂ surface were controlled by adsorption. The effects of different organics such as humic acid, ionic surfactants, and pharmaceutical substances on AMX removal using CeO₂@SiO₂ were also thoroughly investigated. The high AMX removal efficiencies of about 75% after four regenerations and about 70% from an actual water sample demonstrate that CeO₂@SiO₂-based rice husk is a hybrid nanomaterial for antibiotic removal from water environments.

Remarkable enhancement of thermal stability of epoxy resin through the incorporation of mesoporous silica micro-filler

For the first time, we incorporated mesoporous micro-silica (5 μm, pore size = 50 nm) as a filler in epoxy resin aiming to enter polymer into the pore of the silica. As expected, the thermal stability of the composite increased remarkably, followed by noteworthy thermal degradation kinetics when compared to the controlled cured epoxy resin. Composites were prepared by the direct dispersion of modified nano-silica, modified mesoporous micro-silica, unmodified mesoporous micro-silica, non-porous micro-silica, and irregular micro-silica of various pore sizes as fillers in diglycidyl ether of bisphenol-A epoxy resin via ultra-sonication and shear mixing, followed by oven-curing with 4,4-diaminodiphenyl sulfone. DSC and TGA analyses demonstrated a higher glass transition temperature (increased by 3.65–5.75 °C) and very high activation energy for thermal degradation (average increase = 46.2%) was obtained for the same unmodified silica composite compared to pure epoxy, respectively.

Taxonomic profiling of bacteria and fungi in freshwater sewer receiving hospital wastewater

Consistent discharges of hospital wastewaters (HWWs) pose ecological risk to the biome of the receiving environment with cumulative effect on its healthiness. Understanding the taxonomic profile of microorganisms in the impacted systems is required to establish taxa that are bio-indicators of toxicants, and provide possible taxa for mitigating ecotoxicity of the HWWs. Geochemistry, pollution status and ecotoxicity of heavy metals (HMs) in HWW-impacted sewer (LU) were assessed. The microbiome profiling was based on 16S rDNA and ITS of 18S rDNA metagenomes. The degree of HMs contamination exceeded 50 and HMs pollution load index of LU was severe (1,084), which consequently exerted severe risk (1,411,575 toxic response factors) with very high toxic responses of Co, Cu, Pb, and Cd. Eco-toxicological impact of the HMs on LU skewed microbiome towards Proteobacteria (43%), Actinobacteria (18%), and about 5% apiece for Chloroflexi, Acidobacteria, Plantomycetes, and Bacteroidetes. Likewise, the relative abundance of in LU inclined towards Ascomycota (59%), Basidiomycota (17%) and unclassified Eukarya_uc_p (16%). Exclusively found in LU sediments were 44,862 bacterial species and 42,881 fungi taxa, while 72,877 and 53,971 species of bacteria and fungi, respectively, were found missing. Extinction and emergence of bacteria and fungi taxa in LU were in response to HMs ecotoxicity and the need for natural attenuation processes respectively. The profiled taxa in LU may be plausible in bioremediation strategies of the impacted system, and in designing knowledge-based bioreactor system for the treatment of HWWs before discharge into the environment.

Fabrication of Highly Porous Polymeric Nanocomposite for the Removal of Radioactive U(VI) and Eu(III) Ions from Aqueous Solution

In the present study, a polymeric nanocomposite, CoFe2O4@DHBF, was fabricated using 2,4 dihydroxybenzaldehyde and formaldehyde in basic medium with CoFe2O4 nanoparticles. The fabricated nanocomposite was characterized using FTIR, TGA, XRD, SEM, TEM, and XPS analyses. The analytical results revealed that the magnetic nanocomposite was fabricated successfully with high surface area 370.24 m2/g. The fabricated CoFe2O4@DHBF was used as an efficient adsorbent for the adsorption of U(VI) and Eu(III) ions from contaminated water. pH, initial concentration, adsorption time, and the temperature of the contaminated water solution affecting the adsorption ability of the nanocomposites were studied. The batch adsorption results exposed that the adsorption capacity for the removal of U(VI) and Eu(III) was found to be 237.5 and 225.5 mg/g. The adsorption kinetics support that both the metal ions follow second order adsorption kinetics. The adsorption isotherm well fits with the Langmuir adsorption isotherm and the correlation coefficient (R2) values were found to be 0.9920 and 0.9913 for the adsorption of U(VI) and Eu(III), respectively. It was noticed that the fabricated nanocomposites show excellent regeneration ability and about 220.1 and 211.3 mg/g adsorption capacity remains with U(VI) and Eu(III) under optimum conditions.

The fabrication of an MoS2 QD-AuNP modified screen-printed electrode for the improved electrochemical detection of cefixime

Herein, we report a voltammetric method for the nanomolar detection of cefixime, a third-generation antibiotic. The determination of cefixime is validated on a glassy carbon electrode (GCE) as well as on a screen-printed carbon electrode (SPCE). In the present study, we have reported a facile "one step simple hydrothermal synthesis" of MoS2 quantum dots and with the oxidation of aurochloric acid for the further formation of an MoS2 QD-AuNP composite. The as-synthesized nanocomposite was characterized via UV-Vis spectroscopy, FTIR spectroscopy, XRD, TEM and EDX techniques, and further applied in the modification of working electrodes, showing excellent electroactivity. The sensing of cefixime was done via cyclic and differential pulse voltammetry techniques. The presence of the only anodic peak in the voltammogram reveals the irreversible oxidation of cefixime in the potential range of about 1.3 ± 0.1 V vs. Ag/AgCl. The study was also performed at different scan rates, which indicate a diffusion-controlled mechanism. The proposed cefixime sensor showed a linear response in the concentration range of 0.33-90.82 μM (at S/N = 3) with a limit of detection (LOD) of 3.9-4.5 nm. The electrochemical sensitivity is calculated as 8.63 μA μM-1 cm-2 and 7.07 μA μM-1 cm-2 in buffer and pharmaceutical formulation (commercially available cefixime tablet), respectively. The effects of several interferents were also investigated. The proposed sensor is effectively used for estimating cefixime in phosphate buffer and the commercially available cefixime tablets with no cross-reactivity or matrix effects and shows a promising prospect for real applications.

Study on Adsorption and Aggregation in the Mixed System of Polyacrylamide, Cu(II) Ions and Innovative Carbon-Silica Composite

The paper presents an original study on adsorption and aggregation phenomena in a mixed system consisting of a macromolecular compound, heavy metal ions and an innovative adsorbent. The authors used ionic polyacrylamides (PAM), Cu(II) ions and carbon–silica composite (C-SiO₂) in the experiments. Such a system has not yet been described in the literature and therefore, the article is of significant novelty and great importance. The composite was prepared by mixing phenol–formaldehyde resin with silica and pyrolysis at 800 °C. The adsorbed amounts of Cu(II) ions and PAM were determined spectrophotometrically. C-SiO₂ was characterized using potentiometric titration, microelecrophoresis and Fourier Transform Infrared Spectroscopy (FTIR) analysis. In turn, the C-SiO₂ aggregation was established turbidimetrically as well as using a particle size analyzer. The obtained results indicated that both Cu(II) ions and ionic polyacrylamide were adsorbed on the composite surface at pH 6. The highest noted adsorbed amounts were 9.8 mg/g for Cu(II) and 35.72 mg/g for CT PAM-25%. Cu(II) ions increased the anionic PAM adsorbed and reduced the cationic PAM one. The adsorption of anionic PAM (50 ppm) stimulated the solid aggregation significantly. What is more, Cu(II) ions enhanced this process. The size of particles/aggregates formed without additives equaled 0.44 μm, whereas in the mixed Cu(II)/AN PAM system, they were even at 1.04 μm.

Removal of Lindane from Aqueous Solution Using Aluminum Hydroxide Nanoparticles with Surface Modification by Anionic Surfactant

In the present study, we investigated the removal of an emerging pesticide lindane from aqueous solution using synthesized aluminum hydroxide Al(OH)₃ (bayerite) nanomaterials with surface modification by an anionic surfactant sodium dodecyl sulfate (SDS). The Al(OH)₃ nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and zeta potential. The lindane removal using SDS-modified nano-aluminum hydroxide nanoparticles (SMNAH) achieved removal of up to 93.68%, which was 3.3 times higher than that of nano-aluminum hydroxide nanoparticles. The adsorptive removal conditions were studied and found to have an adsorption time of 60 min, a pH of 6, an adsorbent dosage of 25 mg/mL and an ionic strength of 10 mM NaCl. After reusing four times, the removal efficiency of lindane using SMNAH still reached 75%. Two-step adsorption can fit adsorption isotherms of lindane onto SMNAH at two salt concentrations. On the basis of the change in zeta potential, surface functional groups and adsorption isotherms, we suggest that the formation of a bilayer micelle induced the removal of lindane.

Adsorptive Removal of Antibiotic Ciprofloxacin from Aqueous Solution Using Protein-Modified Nanosilica

The present study aims to investigate adsorptive removal of molecular ciprofloxacin using protein-modified nanosilica (ProMNS). Protein was successfully extracted from Moringa seeds while nanosilica was synthesized from rice husk. Fourier-transform infrared (FTIR), ultraviolet visible (UV-Vis) and high-performance liquid chromatography (HPLC) were used to evaluate the characterization of protein. Adsorption of protein onto nanosilica at different pH and ionic strength was thoroughly studied to modify nanosilica surface. The removal efficiency of antibiotic ciprofloxacin (CFX) increased from 56.84% to 89.86% after surface modification with protein. Effective conditions for CFX removal using ProMNS were systematically optimized and found to be pH 7.0, adsorption time 90 min, adsorbent dosage 10 mg/mL, and ionic strength 1 mM KCl. A two-step model was successfully used to fit the adsorption isotherms of CFX onto ProMNS at different ionic strength while a pseudo-second-order model could fit adsorption kinetic of CFX onto ProMNS very well. Maximum adsorption capacity was very high that reached to 85 mg/g. Adsorption of CFX onto ProMNS decreased with increasing KCl concentration, suggesting that adsorption of CFX onto ProMNS is mainly controlled by electrostatic attraction between positively charged ProMNS surface and anionic species of CFX. Adsorption mechanisms of CFX onto ProMNS were discussed in detail based on adsorption isotherms, the change in surface charge by zeta potentail and the change in functional groups by FT-IR. The removal of CFX after three regenerations was greater than 73% while CFX removal from an actual hospital wastewater using ProMNS reached to 70%. Our results suggest that ProMNS is a new and eco-friendly adsorbent to remove antibiotics from aqueous solutions.