Equilibrium Data Research Articles

Cell Morphology, Material Property and Ni(II) Adsorption of Microcellular Injection-Molded Polystyrene Reinforced with Graphene Nanoparticles

Graphene’s incorporation into polymers has enabled the development of advanced polymer/graphene nanocomposites with superior properties. This study focuses on the use of a microcellular foamed polystyrene (PS)/graphene (GP) nanocomposite (3 wt%) for nickel (II) ion removal from aqueous solutions. Adsorption behavior was evaluated through FTIR, TEM, SEM, TGA, and XRD analyses. Key factors, including initial ion concentration, pH, temperature, and sorbent dosage, were examined. Results showed optimal nickel removal at specific pH levels with removal efficiency decreasing from 91 to 80% as Ni (II) concentrations increased from 10 to 100 mg/L. The adsorption capacity improved from 11 to 130 mg/g. Equilibrium data aligned with Langmuir and Freundlich isotherm models, while adsorption kinetics followed a second-order kinetic model. These findings highlight the potential of PS/GP nanocomposites for nickel ion removal, offering a promising solution for small-scale industrial applications.

Poly-(2-aminothiophenol) Functionalized Petroleum Coke for Fast Simultaneous Sequestration of Cd(II) and Pb(II) Ions from Industrial Effluents

Background: Nowadays, the challenge between clean water production and promoting an eco-friendly sorbent for the simultaneous fast and efficient removal of heavy metal ions is a hot topic and has attracted much attention. Objective: The objective of this study was to fabricate a novel material (PATP@PET) by incorporating poly-(2-amino thiophenol; PATP) into the matrix of Saudi Arabian petroleum coke (PET) for simultaneous fast and efficient removal of heavy metal ions. objective: The fabrication of a novel material (PATP@PET) by incorporating poly-(2-amino thiophenol; PATP) into the matrix of Saudi Arabian petroleum coke (PET) for simultaneous fast and efficient removal of heavy metal ions Method: The FTIR, EDX, SEM, and XRD techniques assessed the chemical structure and surface morphology of the thio-functionalized petcoke. The effects of medium pH, mass dosage of sorbent, metal ion concentration, and coexisting ions were investigated and optimized using batch sorption. Result: The excellent sorption capacity of PATP@PET sorbent towards the divalent lead and cadmium ions (98.44% and 312.5 mg.g-1 for Pb(II) and 90.15% and 217.4 mg.g-1 for Cd(II)) was realized by strong complex formation with the sulfur atoms of green petcoke and the thiol groups of poly-2- aminothiophenol moieties. The adsorption equilibrium data was best fitted to the pseudo-secondorder kinetic model and Langmuir adsorption isotherm. The reusability performance was tested for 10 cycles, and the simultaneous removal of Pb(II) and Cd(II) ions from industrial effluents was accomplished in 30 minutes with 100% removal efficiency at pH 6-7. Conclusion: PTAP-PET also demonstrated amazing performance for Cd(II) and Pb(II) removal in industrial wastewater samples. Subsequently, PTAP-PET contributes to developing fast, efficient, low-cost water remediation solutions for heavy metal ions that can potentially be translated into industrial- scale applications.

Separation Process for Methanol–Methylal–Methyl Formate Multicomponent System in Polyformaldehyde Production Waste Liquid: Modeling and Techno-Economic Analysis

The vapor–liquid equilibrium (VLE) data of the ternary system methanol–methyl formate–methylal was measured at atmospheric pressure using a modified Rose equilibrium kettle with vapor–liquid double circulation method. The experiment data were correlated with the NRTL, UNIQUAC, and Wilson activity coefficient model equations. The results shown that the root mean square deviation (RMSD) between the calculated and simulated values of the three models followed the order: UNIQUAC ≈ NRTL < Wilson, and except for the RMSD (T) in the range of 0.4–0.5, the others are less than 0.01. In addition, the NRTL model was selected to link with Aspen Plus software to simulate the separation process of polyformaldehyde (POM) waste liquid. The simulation results show that the methyl formate in POM waste stream can be purified by simple distillation, while the methylal separated from the POM waste liquid, which was affected by factors like the azeotropic behavior of binary components, necessitates a complex distillation process. Under optimal operating conditions, the recovery yield of methyl formate through direct distillation can reach 99.7%, with an economic benefit of 6960.1 CNY per ton of waste liquid. Although the economic benefit of the multi-component distillation reach 7281.2 CNY, the increase in the number of equipment and the complexity of the process have negative impacts.

Production of Nanofibers Composed of CuO for the Removal of Pb(II) from Aqueous Solutions

Pollution by heavy metals such as lead is a major concern, since exposure to these metals can lead to various adverse health effects. In this work, nanofibers composed of CuO (CuONFs) were developed as a novel and promising material for Pb(II) adsorption. There have been no previous reports concerning the production of polyacrylonitrile nanofibers modified with copper sulfate pentahydrate, followed by calcination, to be utilized as a Pb(II) adsorbent. The nanofibers were obtained using the centrifugal spinning method and then were characterized before and after a calcination step using analytical techniques. Adsorption parameters were investigated, including pH, contact time, adsorbate concentration, and temperature. Satisfactory Pb (II) adsorption was reached at 298 K, pH 5.8, and a maximum adsorption of 151.34 mg g−1 was achieved, predicted by the Hill model. The kinetic data proved that Pb (II) adsorption better fitted the pseudo-second-order model, while the Hill model was confirmed to best fit the equilibrium data. Thermodynamic parameters demonstrated that the lead adsorption was favorable, spontaneous, and exothermic. The CuONFs maintained 97.51% of their initial adsorption capacity after two adsorption/desorption cycles. The results showed that CuONFs have excellent potential as an adsorbent for Pb(II), while also showing high stability during reuse.

Modification of a silicate xerogel with cetyltrimethylammonium bromide for the adsorption of tartrazine yellow dye

Synthetic dyes present in industrial wastewater cause adverse effects on aquatic organisms and humans. Tartrazine yellow (TY) is an anionic dye used in textiles, cosmetics, and food industries, which has adverse effects on diet consumption. An alternative method for removing residues from wastewater is the adsorption process using silica xerogels. Though the use of silica materials as adsorbents of dyes has already been studied, xerogels used for this purpose have not yet completely known. The work reported here describes the study of the adsorption capacities of two silica xerogels, prepared by the sol-gel method via acid catalysis, for TY from its aqueous solutions. These two silica xerogels were synthesized using tetraethylorthosilicate as a precursor. The first was named silica xerogel unmodified (SiO2-UN), and the second was modified with a surfactant, cetyltrimethylammonium bromide (CTAB), named SiO2-CTAB. The adsorption process was realized using Ultraviolet-visible spectroscopy. The pseudo-second-order model best described the adsorption kinetics. The equilibrium data fit well to the Freundlich adsorption isotherm for SiO2-UN while for SiO2-CTAB, the results best fitted to the Langmuir isotherm model. SiO2-CTAB had a higher maximum adsorption mass value of 9,62 mg g-1 for TY than SiO2-UN, which could be attributed to electrostatic interactions. The results indicate the potential use of SiO2-CTAB as adsorbent for TY.

Detoxification of dairy industry effluent from toxic metal ions: Preparation and characterization of a magnetized adsorbent derived from agricultural residues

This study investigated the potential of a mixture of agricultural wastes for the preparation of an adsorbent and evaluated its efficiency in removing Co(II) and Cu(II) ions. Brunauer-Emmett-Teller analysis revealed a surface area of 89.57 m2/g, a total pore volume of 4.92 cm³/g, and an average pore diameter of 43.26 nm. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed a layered structure, uniform pore distribution, and successful adsorption of cobalt and copper ions. Vibrating sample magnetometry analysis demonstrated superparamagnetic behavior, with a saturation magnetization of 52.8 emu/g. Fourier-transform infrared spectroscopy identified oxygen-containing functional groups formed during activation, which significantly enhanced the adsorbent’s adsorption capacity. Equilibrium data for pollutant adsorption were well-described by the Freundlich isotherm, with maximum adsorption capacities of 91.7 mg/g for Co(II) and 89.9 mg/g for Cu(II). At 50 °C, the correlation coefficients (R2) were determined to be 0.969 for Co(II) and 0.960 for Cu(II). Under optimal conditions, 75 mg of adsorbent at 50 °C, pH 6.5, and 30 min, the adsorbent achieved 92–93% removal of pollutants from real dairy effluent and 95–96% from synthetic effluent. The process highlights its potential as a sustainable solution for dairy effluent treatment and agricultural waste management, with scalability for industrial applications.

Azithromycin removal from water via adsorption on drinking water sludge-derived materials: Kinetics and isotherms studies.

In this study, we utilized drinking water treatment sludge (WTS) to produce adsorbents through the drying and calcination process. These adsorbents were then evaluated for their ability to remove azithromycin (AZT) from aqueous solutions. The L-500 adsorbent, derived from the calcination (at 500°C) of WTS generated under conditions of low turbidity in the drinking water treatment plant, presented an increase in the specific surface area from 70.745 to 95.471 m2 g-1 and in the total pore volume from 0.154 to 0.211 cm3 g-1, which resulted in a significant AZT removal efficiency of 65% in distilled water after 60 min of treatment. In synthetic wastewater, the rate of AZT removal increased to 80%, in comparison, in a real effluent of a municipal wastewater treatment plant, an AZT removal of 56% was obtained. Kinetic studies revealed that the experimental data followed the pseudo-second-order model (R2: 0.993-0.999, APE: 0.07-1.30%, and Δq: 0.10-2.14%) suggesting that chemisorption is the limiting step in the adsorption using L-500. This finding aligns with FTIR analysis, which indicates that adsorption mechanisms involve π-π stacking, hydrogen bonding, and electrostatic interactions. The equilibrium data were analyzed using the nonlinear Langmuir, Freundlich, and Langmuir-Freundlich isotherms. The Langmuir-Freundlich model presented the best fitting (R2: 0.93, APE: 2.22%, and Δq: 0.06%) revealing numerous interactions and adsorption energies between AZT and L-500. This adsorbent showed a reduction of 19% in its AZT removal after four consecutive reuse cycles. In line with the circular economy principles, our study presents an interesting prospect for the reuse and valorization of WTS. This approach not only offers an effective adsorbent for AZT removal from water but also represents a significant step forward in advancing sustainable water treatment solutions within the framework of the circular economy.

Evaluation of carbon nanotubes/modified empty fruit bunch for adsorptive removal of methylene blue

Dyes pose a significant risk to water pollution due to their toxic components which endangers both the environment and human health. The present research is to investigate the effectiveness of carbon nanotubes (CNTs) that were mixed with modified empty fruit bunch (MEFB) for the elimination of Methylene Blue (MB) dye. The CNTs/MEFB was prepared using a simple reflux method. The findings indicated that 0.25g of adsorbent dosage has the high removal rate and 30 mg/l is the ideal initial concentration. The pH of 8 shows the excellent methylene uptake along with ideal temperature of 40°C. The Langmuir and Freundlich adsorption isotherm model were studied, and the equilibrium data was best discussed by the Langmuir isotherm model. Through the results obtained, CNTs/MEFB adsorbent shows an excellent result in Methylene Blue uptake.

High-performance cellulose acetate fibers-loaded Al[sbnd]ca layered double oxide adsorbents towards efficient elimination of anionic pollutants: Mechanism adsorption and RSM-CCD approach

In the present research, we investigate Congo red (CR) removal by layered double hydroxide and oxide AlCa on cellulose acetate (CA) fiber as anion-adsorbents in aqueous solution. The as-prepared composite was characterized by FE-SEM, XRD, FTIR, EDS-mapping and BET-BJH analyses. The CR adsorption ability on AlCa LDH/CA and AlCa LDO/CA adsorbents was evaluated. The removal property, dye adsorption and filtration properties of the AlCa LDO/CA composite were studied for removal CR based on central composite design (CCD) technique through investigating operational variables (temperature, adsorbent dosage, pH and contact time). The fabricated AlCa LDO/CA composite indicates a high removal efficiency up to 98.7 % for the CR removal in the 16 min. The data of the adsorption equilibrium were described by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms, and exhibited that AlCa LDH/CA fibers and AlCa LDO/CA fibers followed a pseudo-second-order kinetic model and Langmuir isotherm. The stability of Al-Ca-LDO/CA fibers nanocomposite was indicated that it was >95 % after eight cycles for removal of CR in the batch method on stirrer. The findings illustrated that appropriate AlCa LDO/CA fiber could be an efficient technique for CR elimination.

Facile fabrication of novel magnetic chitosan-alginate @ pomegranate peel extract nanocomposite for the adsorptive removal of naphthalene from aqueous solutions.

The prevalent presence of naphthalene contamination in aquatic ecosystems is a significant concern due to its carcinogenic and priority pollutant properties. This study focuses on the synthesis of magnetized chitosan/alginate/pomegranate peel extract nanocomposites (Fe3O4/PPE/Cs-Alg), was characterized by Zeta potential, vibrating sample magnetometer (VSM), Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The results predicted that the successfully synthesis of Fe3O4/PPE/Cs-Alg. The study evaluates the efficacy of the nanocomposite in naphthalene removal, considering operational parameters like pH, varied initial naphthalene concentrations, nanocomposite doses and contact time . The maximum adsorption capacities of naphthalene optimal conditions were 88.12mg/g for 50ppm initial naphthalene concentration. The Langmuir, Freundlich, Temkin and Sips isotherms were applied to analyze the experimental equilibrium data. The Sips isotherm was identified as the most suitable model, as evidenced by the highest (R2=0.97), Also, the adsorption data conformed well to the pseudo-second-order kinetics model (R2=0.99). The thermodynamic study showed positive values for ΔH° and ΔS° throughout the adsorption process respectively, implying an endothermic behavior. Therefore, we found that it can significantly remove naphthalene in aqueous environments and hence could be useful for cleaning up the environment from Poly Aromatic Hydrocarbon.

Multi-walled carbon nanotubes/TiO2/Chitosan nanocomposite for efficient removal of malachite green dye from aqueous system: A comprehensive experimental and theoretical investigation.

This study presents the preparation, characterization, and application of a novel Multi-walled carbon nanotubes/TiO2/chitosan (MWCNT/TiO2/CS) nanocomposite, prepared using a hydrothermal method, for the removal of malachite green (MG) dye from aqueous solutions. Adsorption studies revealed optimal dye removal within 15min of adsorption equilibrium time, with maximum removal efficiency of 98.53% at pH7.0, dose 0.4g/L and 298K. Isotherm studies showed the Langmuir model best described the adsorption equilibrium data with maximum monolayer adsorption (qm) value was found to be 269.98mg/g at 298K. Kinetic analyses favored the pseudo-second-order model with qcal value was found to be 201.6mg/g at Co=100mg/L. Thermodynamic investigations indicated an exothermic, spontaneous adsorption process. Seven successful adsorption-desorption cycles were achieved using HCl as an eluent (97.65% desorption). Theoretical reactivity parameters derived from DFT calculations corroborated experimental findings, elucidating the molecular-level mechanisms underlying the efficient adsorption of MG onto the MWCNT/TiO2/CS surface. The strong electrophilic nature and electron-accepting character of the MG molecule, along with its ability to form electronic interactions, explain its high adsorption affinity. These findings demonstrate the potential of MWCNT/TiO2/CS nanocomposite as an effective and sustainable solution for MG dye removal from aqueous environments.

Preparation and characterization of nano composites from metal oxides and activated carbon from banana peel (MO@BPAC, MO=NiO, CuO and ZnO) for 2 nitrophenol removal from aqueous solutions.

In this research, activated carbon from banana peel (BPAC) was prepared by calcination (600°C) method. Nano composites MO@BPAC (MO=NiO, CuO and ZnO) were prepared and then were characterized by XRD, FTIR, FESM, EDX, BETand TGA methods. Formation of MO@BPAC nanocomposites was confirmed by analysis methods. The XRD patterns showed formation of nanocomposites did not change crystalline phase of metal oxides. TGA analysis also showed the MO@BPAC had high thermal stability to 780°C. Removal of 2-nitrophenol by MO@BPAC nanocomposites was studied. The optimum contact time of 80min for NiO@BPAC, 100min and 120min for ZnO@BPAC and CuO@BPAC was observed. The order of percent removal of 2-nitrophenol by nanocomposites was as follow: NiO@BPAC>CuO@BPAC>ZnO@BPAC. The maximum removal of 2-nitrophenol 40mg L-1was attained at pH 9 and sorbent dose of 0.12g. The kinetic studies showed adsorption of 2-nitrophenol was described better by pseudo second order kinetic model than pseudo first order kinetic. The studies for equilibrium data showed Langmuir isotherm model gave better correlation with the experimental data (qe=303mgg-1 for NiO@BPAC). Thermodynamic parameters indicated adsorption of 2-nitrophenol by MO@BPAC nanocomosites were spontaneous and endothermic. The NiO@BPAC could be reused fourth cycles.

Synthesis and Characterization of Oxidized Starch-Montmorillonite Composite for Efficient Removal of Crystal Violet Dye from Aqueous Solutions

An effective adsorbent was synthesized by modifying Montmorillonite (MMT) clay with oxidized starch, aiming to remove crystal violet (CV) dye from aqueous solutions. The chemical modifications in the MMT-oxidized starch composite were characterized using Fourier-transform infrared spectroscopy (FTIR), confirming the successful integration of oxidized starch with MMT. The adsorption performance was evaluated under varying conditions, including initial dye concentration, adsorbent dosage, pH, and contact time. Kinetic analysis revealed that the adsorption process followed a pseudo-second-order model, while equilibrium data were fitted by the Langmuir isotherm, indicating monolayer adsorption. The adsorbent demonstrated a high adsorption capacity of 25.4 mg/g at pH 7 for CV dye. Thermogravimetric analysis (TGA) confirmed the thermal stability of the synthesized material and these findings suggest that oxidized starch-MMT is a promising alternative for the efficient removal of cationic dyes like crystal violet from wastewater, with significant implications for scalable water treatment applications and broader environmental remediation efforts in both industrial and municipal settings.

Preparation, characterization, and use of trimethoxy[3-(methylamino)propyl]silane functionalized SBA-15 for Congo Red adsorption

Mesoporous materials have a broad range of applications in industry, and one of which is their potential use in adsorptive separations. This research investigates the use of a secondary amine-functionalized SBA-15 for the separation of a diazo dye, Congo Red (CR), from aqueous solutions. The synthesized SBA-15 was modified with trimethoxy[3-(methylamino)propyl] silane by a post-grafting method. The produced material was characterized using X-ray diffraction, N2 physisorption, scanning electron microscopy, and transmission electron microscopy. The hexagonal mesostructure was preserved after functionalization; however, the specific surface area, pore diameter, and total pore volume of SBA-15 silica decreased. The adsorption of the diazo dye reached equilibrium by 50 minutes, and the data followed pseudo-second-order kinetics. While the yield increased with rising dosage and temperature, it decreased with CR concentration. The maximum adsorption capacity of functionalized SBA-15 (F-SBA-15) for CR uptake was found to be 211.07 mg/g. Thermodynamic data and parameters indicated the potential combination of physical and chemical interactions occurring during the adsorption process. The separation was endothermic and non-spontaneous; the equilibrium data fitted to the Freundlich adsorption isotherm at all tested temperatures. This study demonstrates that the secondary amine-functionalized SBA-15 can be used for the elimination of a toxic anionic diazo dye from aqueous solutions.

Removal of Diesel from Aqueous Solutions by a Combined Adsorption and Microbial Degradation Process

Diesel contamination in water bodies poses a significant environmental challenge due to the toxic effects of its water-soluble fraction (WSF) on aquatic ecosystems and human health. The aim of this work was the design of a new technological procedure for the purification of water contaminated with the WSF of diesel. The procedure is based on the adsorption of organic pollution on an organozeolite, after which the biodegradation of the adsorbed pollutant takes place. The material for obtaining organozeolite was a natural zeolite from the Zlatokop deposit (Vranje, Serbia). The zeolitic surface was modified with hexadecyltrimethylammonium bromide (HDTMA-Br), a cationic quaternary ammonium salt. The adsorption experiments, with initial WSF concentrations of 2.5–25 mg/L, at pH 6 and at 20 C, were performed in a batch system using organozeolite, and the results showed that more than 90% of the WSF of diesel was removed, reaching equilibrium after 1 h. The maximum adsorbed capacity of organozeolite for the removal of the WSF of diesel fuel from water under the tested conditions was 22.2 mg/g. Equilibrium data were well fitted by a linear isotherm model, while a pseudo-second-order equation well fitted the kinetic data. After adsorption, a 15-day biodegradation experiment was carried out under batch conditions. The results showed that the examined consortium of microorganisms degraded 80% of the adsorbed contaminant. Additional respirometric analyses showed that, in parallel with the degradation of the contaminant, the degradation of the long-chain HDTMA ions at the surface of the organozeolite also occurred. To the best of our knowledge, this is the first study combining adsorption and biodegradation to remove the WSF of diesel from water.

Sustainable Adsorbent: Activated Carbon From Waste Styrofoam for Efficient Aluminum Removal.

This paper reports on batch investigations utilizing activated carbon (AC) made from waste Styrofoam to adsorb aluminum (Al3+) from aqueous solutions. The AC morphology and structure were examined using Fourier-transform infrared spectroscopy, scanning electron microscopy, and surface area analysis. The factors affecting the performance of adsorption were thoroughly examined. Al3+ removal was found to be maximal, that is, 98.65% using 0.2 g of AC at 90 min in a solution of pH 5 maintained at 60°C. Using a flame-mode atomic absorption spectrophotometer (AAnalyst 700, PerkinElmer, USA), the quantity of Al3+ in the adsorption solution was measured. For the purpose of studying adsorption, the pseudo-first-order, pseudo-second-order, Langmuir, Freundlich, Temkin, Jovanovich, and Harkins-Jura isotherms were analyzed. The kinetic study shows that the adsorption of Al3+ onto Al3+ is controlled by pseudo-second-order kinetics. It was observed that among these models, the Langmuir model showed the most favorable fit for the equilibrium data on the removal of Al3+ onto AC, with a strong fit (R2 = 0.995). The values of thermodynamic parameters such as entropy (ΔS°), Gibbs free energy (ΔG°), and enthalpy (ΔH°) show that the adsorption process is spontaneous and exothermic in nature. In Al3+ solutions with low concentrations, the AC exhibited a high adsorption rate. In addition, a check of the error function was performed. To find out if the AC could be utilized again after the adsorption procedure, desorption investigations were carried out. Due to its high adsorption capacity (> 98%) and porous structure, the prepared AC shows significant promise as an alternative adsorbent for Al3+. These findings demonstrate that the AC is both effective and efficient in removing Al3+ from wastewater.

KOH-activated tire pyrolysis char as an adsorbent for chloroorganic water pollutants

Activated carbons (ACs) produced from end-of-life tires with different tire pyrolysis char (TPC)-to-activator (KOH) ratios of 1:2, 1:3, and 1:4 were prepared and characterized. These materials were used as adsorbents for the removal of two common chloroorganic water contaminants such as 2,4-dichlorophenol (DCP) and 2,4-dichlorophenoxyacetic acid (2,4-D). The adsorption kinetics, equilibrium adsorption, and effects of solution pH were investigated. The adsorption of both adsorbates was found to be pH-dependent and preferred in acidic environments. The adsorption kinetics was evaluated using pseudo-first-order and pseudo-second-order kinetic models and mechanism - using Weber-Morris and Boyd models. Results demonstrated that the adsorption of DCP and 2,4-D on all ACs followed the pseudo-second-order model and was controlled by film diffusion. The Langmuir isotherm described the equilibrium data better than the Freundlich isotherm model. The maximum adsorption capacity of DCP adsorbed on AC1:2, AC1:3, and AC1:4 at equilibrium was 0.582, 0.609, and 0.739 mmol/g, respectively, while the maximum adsorption capacities for 2,4-D were 0.733, 0.937, and 1.035 mmol/g, respectively. The adsorption rate and efficiency were closely correlated with the porous structure of the tested adsorbents. The results showed that the activated carbons obtained from the scrap of end-of-life tires as raw materials could be used as a low-cost and alternative adsorbent for the removal of chlorinated organic pollutants from water.

Glycine-modified chitosan-embedded silver nanoparticles: a green approach to Pb2+ adsorption and bioactivity enhancement

AbstractGlycine-modified chitosan anchored silver nanoparticles (SCG) were synthesized using a green method without a cross-linking agent. UV–Vis, FTIR, XRD, TEM and SEM techniques confirmed the formation of the SCG nanocomposite and silver nanoparticles. The SCG nanoparticles, estimated at 20 nm, are smaller than the chitosan stabilized Ag (SC) nanoparticles. The biological significance of the SCG nanoparticles was assessed through their anti-oxidant and antibacterial activities. SCG nanoparticles demonstrated significant anti-oxidant activity with an IC50 of 133 µg ml−1, surpassing that of SC nanoparticles. The ZoI of was found to be 30 mm for the S. aureus and E. coli bacterial strains indicating excellent antimicrobial activity. The efficiency of SCG nanoparticles in removing Pb2+ ions was tested using a batch adsorption process. A Central Composite Design (CCD) was employed to optimize the independent variables, and ANOVA results indicated the CCD model’s reliability and significance with a p-value < 0.0001. The SCG nanoparticles exhibited a high Pb2+ ion loading capacity of 270.2 mg g−1 from aqueous solution with a removal efficiency of 93%. Isotherm and kinetic investigations of the equilibrium data suggest the suitability of Langmuir and pseudo-second-order kinetic models. Thermodynamic studies revealed the process’s spontaneity and exothermic nature. The mechanism of adsorption was found to be ion exchange with a mean potential energy (Es) of 9.4 kJ/mol. These findings suggest that glycine-modified chitosan anchored silver nanoparticles have promising applications in biological and environmental domains.

A novel metal-free perylene-functionalized graphite adsorbent for efficient antibiotic removal from wastewater.

Adsorption remains a widely utilized and effective technique for removing chemical contaminants from polluted water, and novel adsorbents are currently in the process of being developed. The presence of antibiotics residues in aqueous effluents is a potential concern due to their potential adverse effects on living organisms. In this work, perylene tetracarboxylic acid-functionalized expanded graphite (PTCA-EG) was synthesized as a metal-free adsorbent and its potential for efficient treatment of contaminated wastewater with cefalexin (CLX) antibiotic was studied. The experimental variables were modeled and optimized using central composite design (CCD) and response surface methodology (RSM) to maximize adsorption efficiency. In this regard, the contact time of 20min, solution pH of 7.0, adsorbent dosage of 18mg, and initial CLX concentration of 45mg L-1 were found to be the optimum conditions for adsorptive removal of CLX with a maximum efficiency of 99 ± 1.21%. In addition, the adsorption equilibrium data were well analyzed with isotherm, kinetic, and thermodynamic studies. The isotherm results revealed the adsorption process was favorable and took place on the heterogeneous surface. Moreover, the Langmuir maximum adsorption capacity (Qmax) was determined as 220.7mgg-1. Also, thermodynamic parameters revealed the spontaneity and endothermic nature of the adsorption process. The reusability studies demonstrated that the spent PTCA-EG can be easily regenerated through NaOH solution (0.01mol L-1) and reused for six cycles without any significant decrease in its adsorption efficiency. Also, the PTCA-EG showed excellent behavior in adsorptive removal of CLX in real water samples including river water (96.61 ± 1.82%) and hospital effluents (91.91 ± 3.41-93.69 ± 3.06%).

Characterization of sulfamethoxazole biosorption by Rhizopus oryzae biomass: Insights into sorption mechanism

ABSTRACT The occurrence of antibiotics in some environmental compartments is a global concern. Sulfamethoxazole (SMX) is one of the most widely used antibiotics worldwide and is commonly found in the environment. In this paper, the effect of pH and lipids on SMX sorption by the fungal biomass of Rhizopus oryzae was studied. SMX biosorption was characterized by FTIR, kinetic, equilibrium, and thermodynamic studies. The greatest SMX adsorption capacity was found at pH 4.0. Under optimal pH, the adsorption rate of SMX was mostly controlled by intraparticle diffusion. The pseudo-first-order model (q e = 252.72 μg g−1, k 1 = 0.099 h−1) and the linear isotherm (K d = 0.211 L g−1) successfully modeled the kinetic and equilibrium data (R2 > 0.97). Moreover, at equilibrium, the absence of lipids in biomass led to a decrease of 2.98-fold in the adsorption capacity for SMX, from 0.211 to 0.071 L g−1, demonstrating that lipids are mainly responsible for removal. Some functional groups from proteins and chitin/chitosan were also identified as potential adsorption sites. Biosorption of SMX was a spontaneous phenomenon (ΔG 0 from −13.269 to −14.996 kJ mol−1) with endothermic nature (ΔH 0 = 17.595 kJ mol−1), driven by weak ionic and hydrophobic interactions. According to our results, the SMX sorption by R. oryzae biomass can be attributed to both adsorption on the biomass surface and absorption in lipids.