Synthesis and evaluation of a Ni-H2bpda/Fe3O4 nanocomposite with high tetracycline adsorption capacity and broad-spectrum antibacterial activity

In this study, porous activated carbon was produced from coffee waste and used as an effective adsorbent for the removal of humic acid (HA) from seawater and methyl orange (MO) dye from aqueous solutions. Phosphoric acid H3PO4 was used as an activating agent for the chemical activation of these agricultural wastes. The characterization of the activated carbon obtained using a scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy analysis, X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET) method revealed that the activated carbon products exhibited high porosity and the formation of various functional groups. The effects of different parameters were examined using batch adsorption experiments, such as the adsorbent masses, pH, initial pollutant concentration and contact time. The results show that the performance increased with an increased adsorbent mass (up to 0.25 g/L) and decreased initial concentration of the adsorbent tested. On the other hand, this study clearly showed that the adsorption efficiency of the MO on the raw spent coffee grounds (SCGs) waste was around 43%, while no removal was observed for the humic acid. The experiments demonstrated that the activated carbon synthesized from the used coffee grounds (the efficiency was compared with commercial activated carbon (CAC) with a difference of 13%) was a promising alternative to commercially available adsorbents for the removal of humic acid from seawater. To understand and elucidate the adsorption mechanism, various isothermal and kinetic models were studied. The adsorption capacity was analyzed by fitting experimental data to these models. The experimental data for methyl orange dyes were analyzed using Langmuir and Freundlich isothermal models. The Freundlich isotherm model provided a superior fit to the equilibrium data, as indicated by a higher correlation coefficient (R2) than that of the Langmuir model. The maximum adsorption was observed at pH 3. The Freundlich adsorption capacity was found to be 333 mg/g adsorbent. The PAC showed a high adsorption capacity for the MO and HA. The PAC showed the highest adsorption capacities for the HA and MO compared with the other adsorbents used (SCGs and CAC) and would be a good material to increase the adsorption efficiency for humic acid removal in the seawater pretreatment process. In addition, the prepared AC BET surface area was 520.40 m2/g, suggesting a high adsorption capacity. This makes the material potentially suitable for various applications that require a high surface area. These results indicate that high-quality sustainable activated carbon can be efficiently produced from coffee waste, making it suitable for a wide range of adsorbent applications targeting various pollutants.

Alginate-chitosan/hydroxyapatite (Alg-Cs/HAP) beads were prepared as adsorbent to remove methylene blue (MB) and copper ions from an aqueous solution using a batch system. FTIR, TGA, point of zero charge (pHpzc), SEM, XRD, and BET analysis were used to characterize the elaborated material. The effect of several parameters such as initial pH value, adsorbent dose, temperature, contact time, and initial pollutant concentration were also investigated. The obtained results showed that Alg-Cs/HAP exhibit excellent adsorption properties for Cu (II) and MB removal, with high adsorption capacities of copper ions (208.34mg/g) and methylene blue (454.54mg/g). The kinetic of the adsorption process is correlated with the pseudo-first-order for methylene blue and the pseudo-second-order for copper ions. The equilibrium data for MB dye fitted the Freundlich isotherm model, thus implying that the adsorption process consists of multilayer adsorption as well as interactions between the adsorbate and the adsorbent. The equilibrium data for copper ions corresponds closely with the Langmuir model which suggests that the adsorbed molecules occur over a monolayer. Various thermodynamic parameters such as the standard Gibbs energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were calculated. All results indicated that Alg-Cs/HAP material has a good potential for the treatment of wastewater.

Activated carbons were produced from spent tyre pyrolysis char by steam or CO2 activation and evaluated for their performance in rhodamine B (RhB) adsorption in aqueous solutions. The effect of RhB starting concentration (80-150 mg L-1), contact time (0-80 min), temperature (298-318 K) and initial pH on the adsorption process was examined. Pseudo-first-order and pseudo-second-order models were carried out to fit the experimental data to derive RhB adsorption kinetics. Langmuir, Freundlich and Temkin isotherm models were applied to depict RhB adsorption behaviour of the prepared activated carbons. Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were calculated. It has been found that the activated carbons can effectively adsorb RhB due to high mesoporosity and RhB equilibrium adsorption capacity (qe) increased almost linearly with increasing total mesopore volumes, regardless of the activation agents. When BET surface areas are similar, CO2-activated carbon obtained higher qe than steam due to higher mesoporosity of CO2-activated carbon. The results show that pseudo-second-order well fitted the experimental data. RhB starting concentration increased from 80 to 150 mg L-1 causing qe increased from 158 to 251 mg g-1 but RhB removal decreased from 99.7 to 84.5%. The RhB adsorption process follows the Langmuir model and thermodynamic calculation, indicating RhB adsorption is an endothermic, spontaneous process, dominated by both chemisorption and physisorption.

Adsorption of metronidazole antibiotic using a new magnetic nanocomposite from simulated wastewater (isotherm, kinetic and thermodynamic studies)

Modifying alginate beads using polycarboxyl component for enhanced metal ions removal

Sulfamethazine (SMZ) has become a widespread pollutant in aquatic environments, posing serious ecological risks and contributing to the development of antimicrobial resistance. Conventional water treatment techniques are generally inefficient at eliminating such pharmaceuticals; however, adsorption using polymeric resins offers a promising alternative. This study investigates the removal of SMZ using a strong acid cation-exchange resin (Purolite C100E). Batch experiments were conducted to examine the influence of key operational parameters, including pH, contact time, resin dosage, temperature, stirring speed, exchangeable cation form, and the presence of a co-adsorbate. Equilibrium isotherm experiments were performed using initial SMZ concentrations in the range of 20–280 mg/L. Operating conditions (pH 5, resin dosage 1 g/L, and contact time 150 min) were selected to achieve high removal efficiency, while the intrinsic adsorption performance of the resin was evaluated using equilibrium isotherms. The adsorption data were best described by the Langmuir model, yielding a high maximum adsorption capacity (qm) of 338.92 ± 21.46 mg/g, which is superior to many previously reported adsorbents. Kinetic studies showed good agreement with the pseudo-second-order model, and thermodynamic analysis confirmed that the adsorption process is spontaneous and exothermic. FTIR analysis indicated that SMZ adsorption is mainly governed by hydrogen bonding and π–π interactions rather than electrostatic attraction. The resin exhibited good reusability over three adsorption–desorption cycles, and competitive adsorption tests demonstrated high selectivity toward SMZ. These results indicate that Purolite C100E is an efficient, selective, and reusable adsorbent for the removal of sulfonamide antibiotics from contaminated water.

The aim of this work is to investigate the influence of an alkaline pretreatment of the Mediterranean plant Carpobrotus edulis on the adsorption capacity toward the dye methylene blue and to estimate the content of soluble organic matter that can be released into the aqueous solution by this biomaterial. The biomaterial used was characterized by SEM-EDX, SS, FT-IR, pHZ, COD and BOD5. Removal of methylene blue (MB) dye by this biomaterial was carried out and the effects of physicochemical factors such as initial pollutant concentration, adsorbent dose, contact time, pH and temperature were investigated. After adsorbent treatment, the soluble organic matter was reduced by 97%, 96%, and 96% for biological oxygen demand, chemical oxygen demand, and organic matter, respectively. Kinetics and equilibrium studies of MB adsorption on the bioadsorbents were fitted with a pseudo-second order kinetic model and a Langmuir model, respectively. The maximum adsorption amount of the modified C. edulis plant was 153.9 mg/g at 298°K. The thermodynamic parameters show that the adsorption process was possible and spontaneous in nature. The adsorption mechanism of MB on the surface of biomaterials was attributed to the electrostatic interaction and H-bonding. The prepared biomaterial (0.016 U$ per gram) was easily regenerated with aqueous HNO3 solution, with a slight decrease in adsorption capacity up to five cycles. The results of Taguchi experimental design and analysis of variance showed that contact time, adsorbent mass and initial concentration are the most important factors affecting the removal efficiency with a contribution of 43.91%, 32.68%, and 22.95%, respectively. The maximum removal capacity of MB dye in optimal operating conditions was 99.39%, which was obtained at the optimum conditions of m = 1 g, pH 4, T = 35 °C, Ci = 1000 mg/L, tc = 5 min. These results confirm previous results obtained with the batch system and show that this absorbent is also promising for the removal of cationic dyes from wastewater.

Simply synthesized Ca-Al-LDH-thiosulfate as adsorbent for removal of malachite green from aqueous solution

Chitosan/Ag-hydroxyapatite nanocomposite beads as a potential adsorbent for the efficient removal of toxic aquatic pollutants

In this study, cobalt-ferrite nano-composite (CFNC) is used to adsorb chromium and cadmium ions from synthetic wastewater. Adsorptive characteristics of CFNC are determined by various analysis including SEM, FTIR, VSM and BET. Also, effect of different parameters such as solution pH, buffer volume, electrolyte dose, the initial ion concentration, contact time, the adsorbent dose and temperature were studied on adsorption process. The results showed that the maximum recovery of Cd(II) and Cr(III) ions were determined as C0 = 20 mg/L, t = 50 min, T = 25 °C, CFNC dosage = 20 g/L, and pH = 7 (for Cr(III)) and 6 (for Cd(II)). In these conditions, the amount of 100% Cr(III) and Cd(II) were removed from the aqueous solution. Also, the equilibrium study showed that the adsorption process followed the Langmuir model and the maximum adsorption capacity for Cr(III) and Cd(II) ions were obtained 217 and 303 mg/g, respectively which show very high adsorption capacities. In addition, adsorption kinetics showed that the pseudo first-order kinetic model was better than the pseudo second-order kinetic model. Moreover, thermodynamic studies showed that the adsorption process was possible, spontaneous and endothermic.

Fabrication and implementation of bimetallic Fe/Zn nanoparticles (mole ratio 1:1) loading on hydroxyethylcellulose – Graphene oxide for removal of tetracycline antibiotic from aqueous solution

High-performance magnetic carbon materials in dye removal from aqueous solutions

Dye pollution in aquatic environments poses severe threats to ecological systems and human health. Hydrogels, featuring abundant functional groups and large specific surface area, are promising dye adsorbents. We aimed to develop a facile, rapid synthesis strategy for hydrogels with superior swelling performance and high cationic dye adsorption capacity. This was achieved via free radical copolymerization of AA, AMPS, and NVP. The synthesized hydrogel AA/AMPS/NVP exhibits a remarkable swelling ratio of 1202 g·g −1 in deionized water and 175 g·g −1 in 0.9% NaCl solution. Adsorption experiments reveal that the methylene blue (MB) adsorption capacity of the hydrogel is influenced by contact time, initial MB concentration, temperature, and solution pH. Kinetic analysis shows that the adsorption process is fitted by the pseudo‐second‐order model. Isotherm study indicates that MB adsorption follows the Langmuir model, with a maximum adsorption capacity of 1290.54 mg·g −1 . After 5 adsorption–desorption cycles, the MB removal efficiency remains at 58.38%. FT‐IR analysis shows that chemical adsorption dominates the interaction between MB molecules and the hydrogel, involving electrostatic attraction and hydrogen bonding between MB cations and functional groups (COOH, SO 3 H) of the hydrogel. Collectively, AA/AMPS/NVP exhibits great potential as an efficient and reusable adsorbent for the remediation of wastewater.

Effective phosphate adsorption by Zr/Al-pillared montmorillonite: insight into equilibrium, kinetics and thermodynamics

Porous sodium alginate/cellulose nanofiber composite hydrogel microspheres for heavy metal removal in wastewater