Synthesis and evaluation of a highly reusable MIL-101(Fe)/biochar adsorbent for efficient ammonium removal: Kinetic, isotherm, and thermodynamic insights

Wastewater pollution has become a critical global environmental issue. This study focuses on synthesizing of new biosorbents by incorporating extracted lignin into two types of clays: fibrous sepiolite (SP) and phyllosilicate bentonite (BT). The goal was to develop cost-effective adsorbents capable of removing toxic metals, particularly cadmium. The physicochemical properties of the resulting materials were analyzed using various techniques, confirming the effective incorporation of lignin into the clay substrates, resulting in two distinct materials called (SL) and (BL). The effectiveness of the modified clays was thoroughly evaluated by examining adsorption performance, kinetics, thermodynamics, and mechanisms governing Cd (II) adsorption. Equilibrium isotherms and kinetic models demonstrated that Cd (II) adsorption on SP and BT followed the Langmuir and Freundlich isotherms, respectively, displaying pseudo-second-order kinetic behavior for both materials. On the other hand, SL and BL modified clays showed a better fit with Langmuir and Freundlich isotherms, respectively, as well as Elovich and Avrami fractional order kinetics, resulting in high correlation coefficients. The maximum Cd (II) adsorption capacities for SL and BL were determined at 118.44 and 157.32 mg/g, respectively, confirming the high efficiency of the modification. Thermodynamic analysis suggested that the Cd (II) adsorption process is both endothermic and spontaneous.

Polyaniline-derived mesoporous carbon electrode for selective and efficient ammonium removal with in a flow-electrode capacitive deionization system

Efficient ammonium removal through heterotrophic nitrification-aerobic denitrification by Acinetobacter baumannii strain AL-6 in the presence of Cr(VI)

Conventionally, nitrification in biological nitrogen removal (BNR) requires high dissolved oxygen (DO) concentrations (>2 mg L−1), making the process energy intensive. Recent studies have shown that efficient ammonium removal and energy reduction can be realized by operating the nitrification at low DO concentrations (<1 mg L−1). In this study, the low-DO oxic anoxic (low-DO OA) process was operated in a pilot-scale sequencing batch reactor (SBR) over 218 days to evaluate the feasibility of nitrogen removal from low chemical oxygen demand-to-nitrogen ratio (COD/N) tropical municipal wastewater. The results revealed that the low-DO OA process attained high removal efficiency for ammonium (97%) and total nitrogen (TN) (80%) under an average DO concentration of 0.6 mg L−1. The effective TN removal efficiency is attributed to the occurrence of simultaneous nitrification–denitrification (SND) under low DO conditions. Further batch tests revealed that slowly biodegradable COD (sbCOD) in tropical wastewater can support denitrification in the post-anoxic phase, resulting in a high TN removal rate. Compared with high DO concentrations (2 mg L−1), low DO conditions achieved 10% higher TN removal efficiency, with similar ammonium and COD removal efficiency. This study is crucial in promoting the energy efficiency and sustainability of wastewater treatment plants treating low COD/N wastewater.

In this study, the optimum ammonium removal by activation of synthetic zeolite in the aqueous phase was investigated by batch ion exchange adsorption assay, and its surface changes due to activation modification was elucidated accordingly. Among the adsorbents examined, modified synthetic zeolite A-4 was the most effective at ammonium removal. The best activation condition of zeolite A-4 was established by Na+ and 300 °C heat treatment at pH around 6 to 7. Besides, the removal efficiency was investigated under various reaction conditions of pH, adsorbent dosage, stirring speed, and initial ammonium concentration. Finally, the adsorptive capacity Qe of synthetic zeolite A-4 activated by Na+ and heat treatment was determined as 31.9 mg/g at 1,000 mg-N/L of ammonium, whereas that of natural zeolite was measured as 16.0 mg/g. The obtained adsorption data was fitted to both Langmuir and Freundlich isotherm models, and the Langmuir isotherm model provided a better correspondence than the Freundlich isotherm. Finally, regeneration cycles for synthetic zeolite A-4 was determined for further industrial applications and efficient ammonium removal.

Selective and efficient removal of benzo(ghi)perylene from water using silica nanoparticles: Kinetic, isotherm, and thermodynamic insights

Hematite-coated expanded graphite, a newly developed nanocomposite, has demonstrated high efficiency as an adsorbent for the removal of various metal ions and inorganic contaminants from aqueous solutions. To enhance its durability and adsorption performance, hematite nanoparticles were synthesized onto expanded graphite, and the adsorption behavior for inorganic pollutants was investigated at different temperatures. The adsorption isotherms were best fitted by the Langmuir model, indicating monolayer adsorption on a homogeneous surface. The maximum adsorption capacity for phosphorus was determined to be 33.3 mg/g at 298 K. A slight decrease in adsorption capacity was observed with increasing temperature, suggesting that the process is exothermic in nature. Thermodynamic analysis revealed a Gibbs free energy change (<i>Δ</i>G) ranging from –22.4 to –22.6 kJ/mol, an enthalpy change (<i>Δ</i>H) of –89.5 kJ/mol, and an entropy change (<i>Δ</i>S) of –0.2 kJ/mol·K, further confirming the spontaneous and exothermic characteristics of the adsorption process. Combined results from isotherm and kinetic studies indicate that α-Fe<sub>2</sub>O<sub>3</sub>/EG is a promising adsorbent for the efficient removal of trace amounts of phosphorus from water.

Efficient removal of triarylmethane biocide from aqueous solutions using ZnAl/LDH: Adsorption kinetics, isotherms, and thermodynamic insights

Investigating the effect of copper and magnesium ions on nitrogen removal capacity of pure cultures by modified non-competitive inhibition model

ABSTRACTEffectively reclaiming Pb (II) adsorbents is crucial for tackling environmental pollution. Metal–organic framework (MOF) and covalent organic framework (COF) composites, with their multiple functional groups, are anticipated to show outstanding Pb (II) adsorption capabilities. Nevertheless, creating and developing COF and MOF composite adsorbents for highly efficient Pb (II) removal remains a challenge. In this study, we synthesized a core–shell ZnGlu@Bth‐TFPOT‐COF (referred to as M@C) adsorbent via Schiff base reaction. Adsorbent demonstrated remarkable properties, including excellent durability, specificity, and straightforward solid–liquid separation. Under 298 K and pH 6.0 conditions, M@C effectively adsorbed Pb (II) and achieved 49.40 mg/g adsorption capacity within 15 min. Remarkably, it effectively eliminated Pb (II) from a solution containing multiple ions, demonstrating an adsorption efficiency of 99.80% and a Kd (partition coefficient) of 4.99 × 106 mL/g in the presence of 10 other ions. The adsorption process was controlled by the Freundlich isotherm model, and the pseudo‐second‐order kinetic model validated that multilayer chemisorption was the mechanism for removing Pb (II). A thermodynamic study showed that the removal process was both spontaneous and exothermic. M@C exhibited outstanding adsorption performance, achieving a capacity of 476.19 mg/g, and demonstrated exceptional selectivity. This makes it an excellent material for the efficient and selective removal of Pb (II).

Ti2N MXene/Zn-Fe layered double hydroxide nanocomposite for efficient tetracycline removal from environmental waters: Thermodynamic and kinetic insights

Electrospun Graphene Oxide Nanosheets/Polyurethane Nanofibers for Efficient Dye Removal: From Synthesis to Thermodynamic and Kinetic Insights

Electro-oxidation of ammonia using a continuous system equipped with RuO2@Ti mesh anode: Optimization of the design parameters with a focus on energy consumption and removal efficiency

This study focused on the removal of COD and NH4+ from medium‐age leachate. Experiments were performed in a laboratory‐scale upflow anaerobic sludge blanket (UASB), a membrane bioreactor (MBR), and using magnesium ammonium phosphate (MAP) precipitation. MBR and MAP were used for the post‐treatment steps for anaerobically treated leachate to increase the removal of organics and ammonium. The UASB reactor removed nearly all biodegradable organics and supplied constant effluent COD for all concentration ranges of influent leachate. Ammonium removal efficiency in the UASB reactor was relatively low and the average value was ∼7.9%. Integration of MBR to the effluent of UASB reactor increased the average COD removal efficiency from 51.8 to 65.6% and maximum removal efficiency increased to 74.3%. MAP precipitation was applied as a final step to decrease the ammonium concentration in the effluent of UASB+MBR reactors. The effect of pH and the molar ratio of MAP constituents on the removal of ammonium were evaluated. At optimal conditions (pH: 9.0 and Mg/NH4/PO4: 1/1.2/1.2), 96.6% of ammonium was removed and MAP provided additional COD and turbidity treatment. Consequently, the combined system of MBR and MAP precipitation could be used as an appropriate post treatment option for the anaerobically treated medium‐age landfill leachate. © 2009 American Institute of Chemical Engineers Environ Prog, 2010

Seasonal variation of bacterial community in biological aerated filter for ammonia removal in drinking water treatment