Chemisorption Process Research Articles

Efficient multifunctional PPy-NTs/PEI@alginate@NiFe2O4 magnetic beads for heavy metals removal: Experimental design and optimization interpretations

A highly effective magnetic nanocomposite alginate beads (PPy-NTs/PEI@Alg@NiFe2O4) were synthesized using alginate as the encapsulation reagent and polypyrrole/polyethylene imine with nano NiFe2O4 as a functional filler to remove toxic Zn2+ and Pb2+ from polluted water. A response surface methodology (RSM) was used to statistically assess the influences of pH and the adsorbent dose on the adsorption performance. PPy-NTs/PEI@Alg@NiFe2O4 magnetic microbeads exhibited the optimal adsorption capacity qe (18.6 mg/g) at pH 6 and a 2 mg/L dose for Zn2+ removal. In comparison, the optimal qe (32.6 mg/g) was reached at pH 4.5 with a 1.5 mg/L dose for Pb2+ remediation. From batch experiments, maximal absorption capacities of 53.3 mg/g and 22 mg/g were achieved for Pb2+ and Zn2+, respectively, at 313 K. The pseudo-second-order kinetic model fitted the results well, suggesting that the chemisorption process regulates adsorption. Isotherm models indicate the presence of homogeneous adsorption sites from the well-fitting to Langmuir isotherm. An investigation of the effects of temperature and thermodynamic considerations revealed the endothermic nature of Zn2+ and Pb2+ absorption. The Fourier transform infrared spectra showed that –NH, –NH2, and –COO− are the main groups in PPy-NTs/PEI@Alg@NiFe2O4 composite beads that were responsible for Zn2+ and Pb2+ removal from polluted water.

Bi-phenyl derived hyper-crosslinked polymer as a metal-free adsorbent for the removal of pharmaceuticals from water

The global concern of emergent aquatic pollutants, especially pharmaceutical contaminants, emphasizes the necessity for metal-free adsorbents to tackle water contamination issues. In this direction, a biphenyl-derived hyper-crosslinked polymer (poly-biph) was utilized as an adsorbent for the removal of ciprofloxacin (CPX) and doxycycline (DOX) from water. Micro-mesoporous hyper-crosslinked polymeric adsorbent (poly-biph) was synthesized by using bi-phenyl as precursor and formaldehyde dimethyl acetal (FDA) as crosslinker via microwave assisted method. It exhibits specific surface area (SABET) and pore volume of 1088 m2/g and 1.3 cm3/g, respectively. The spectral analysis confirmed the successful crosslinking of biphenyl with the linker FDA. The sorption efficiency of metal-free poly-biph for CPX and DOX was evaluated via batch and continuous flow modes under various operational parameters. poly-biph exhibited swift removal efficiency (>80 %) for CPX and DOX within a min. The batch mode sorption modeling revealed a chemisorption process and remarkable maximum sorption capacity of 470.8 and 425.1 mg/g for CPX and DOX, respectively. The continuous-flow studies of poly-biph revealed the better applicability of the Clark kinetic model with a maximum bed capacity of 313.5 and 372.4 mg/g for CPX and DOX, respectively. Synergistic mechanisms, including π-π interaction, electrostatic interaction, and pore-filling effect, were found to be the main driving forces for the sorptive removal of CPX and DOX onto poly-biph. The findings indicated that poly-biph possesses the ability to effectively eliminate DOX and CPX from the aquatic environment.

Plasma-enhanced atomic layer deposition of carbon films employing a cyclic process of N2/H2 plasma and α, α’-dichloro-p-xylene as a precursor

A novel concept and process were proposed for the plasma-enhanced atomic layer deposition (PE-ALD) of carbon films. α, α’-dichloro-p-xylene (DCX) was used to form the adsorption layer, which was modified using nitrogen/hydrogen (N2/H2) plasma. Through iterative molecular chemisorption and end-group substitution processes, the selective and precise control of carbon deposition by PE-ALD was achieved. The growth per cycle of this process was estimated to be 0.02–0.05 nm/cycle. To determine the chemical reactions that occurred during the PE-ALD process, the IR spectra observed using in-situ Fourier transform infrared spectroscopy were analyzed. The decrease in the Si-OH bond at 3740 cm−1 and the saturation of the increase in CH bending at 1250 cm−1 revealed that the deposition of a DCX monolayer via a dehydrochlorination reaction with isolated OH bonding on SiO2 has been successfully achieved. The change in N(−H)x stretching during the N2/H2 plasma treatment indicated the substitution of exposed C-Cl bonding with C-NH2 bonding on the chemisorbed DCX monolayer surface. Additionally, the composition of the carbon films after 200-cycle PE-ALD was analyzed. Finally, the realization of the concept for PE-ALD of carbon film was confirmed by surface analysis.

Adsorption of Congo red on magnetic cobalt-manganese ferrite nanoparticles: Adsorption kinetic, isotherm, thermodynamics, and electrochemistry.

Magnetic Co0.5Mn0.5Fe2O4 nanoparticles were successfully prepared via the combustion and calcination process, with an average particle diameter of 31.5 nm and a saturation magnetization of 25.25 emu·g-1, they were employed to adsorbe Congo red (CR) from wastewater, the Pseudo-second-order kinetic and Freundlich isotherm were consistent with the adsorption data, indicating that their adsorption was a multilayer chemisorption process, the thermodynamic investigation showed that the adsorption was a favored exothermic process. The ionic strength of Cl- in CR solution had no obvious effect on the adsorption efficiency of Co0.5Mn0.5Fe2O4 nanoparticles, and the maximum adsorbance was 58.3 mg·g-1 at pH 2, decreasing as the pH of the CR solutions increased from 2 to 12. The ion leaching experiment and XRD demonstrated that Co0.5Mn0.5Fe2O4 nanoparticles had excellent stability, and the relative removal rate was 93.85% of the first time after 7 cycles. Cyclic voltammetry and electrochemical impedance spectroscopy demonstrated that CR was adsorbed onto Co0.5Mn0.5Fe2O4 nanoparticles, and the electrical conductivity of Co0.5Mn0.5Fe2O4 nanoparticles decreased after adsorption of CR. Magnetic Co0.5Mn0.5Fe2O4 nanoparticles displayed a promising application in wastewater treatment.

Ionic liquids-assisted integration of biobased materials for sustainable elaboration of nanocomposites using hydroxyethyl cellulose and interlayered clay for efficient separation of Co(II) from multi-component mixtures

This study focuses on the development of eco-friendly biobased adsorbents through a sustainable hydrothermal and freeze-drying synthesis process, utilizing cost-effective bio-sourced materials to minimize energy consumption and waste. The biobased adsorbents were elaborated using hydroxyethyl cellulose-ionic liquids and bentonite clay. The elaborated biocomposites were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy/attenuated total reflection (FTIR/ATR), thermogravimetric analysis (TGA), and electron microscopy-energy dispersive X-ray (SEM–EDX), Brunauer–Emmett–Teller (BET) and zeta potential (ZP). Structural analysis confirms the intercalation and incorporation of HEC-ILs polymeric chains into Be-Na matrix and the formation of biocomposites. The [HEC-ILs/Be-Na] composite was subsequently employed for solid-phase extraction of Co(II) by investigating the effect of pH, initial Co(II) concentrations, time, temperature, and the presence of co-existing ions (Na(I), Li(I), Mn(II), Ni(II), and Al(III)). The adsorption kinetics of Co(II) metal ions were suitably characterized using the pseudo-second-order model (with R2 > 0.99). Furthermore, the adsorption isotherms conformed to the Langmuir model (with R2 > 0.97), suggesting a chemisorption process with an adsorption capacity of 69.8 mg/g. The thermodynamic study reveals that the adsorption process exhibits characteristics of spontaneity and endothermicity (ΔH° = 74.197 kJ mol−1, ΔG° < 0 kJ mol−1). The proposed mechanism for Co(II) adsorption on the developed biocomposite involves electrostatic interactions, ion exchange, and anion-π interactions. The biobased composite exhibited remarkable selectivity for Co(II) and demonstrated great potential as an adsorbent for industrial applications.Graphical abstract

Surface functionalization of XC18 steel using a new transition metal complex for remarkable corrosion performance: Empirical and theoretical studies

Synthesis of transition metal complexes (TMC) having specific characteristics is advantageous for combining their organic and inorganic properties, to help prevent metals from corrosion. In this study, the corrosion inhibition behavior of [N, N’-bis(salicylidene)-2,2-dimethyl-1,3-propanediaminato] copper (II) (CuL) on the surface of XC18 steel surface immersed in 1.0 M HCl was investigated. The thermodynamic and kinetic corrosion parameters were determined using the mass loss (ML) and electrochemical measurement methods. CuL exhibited a good corrosion inhibition efficiency of 96.72 %. The adsorption behavior of CuL followed the Langmuir isotherm model, indicating both physical and chemical interactions. Morphological structural analysis demonstrated that CuL formed a protective film between the surface of XC18 steel and the corrosives elements, thus confirming its adsorption onto XC18 steel surface. Theoretical calculations were consistent with the experimental findings, thereby confirming that the adsorption of CuL onto the steel surface comprises both physisorption and chemisorption processes. These calculations elucidate the specific bonding nature and emphasize the significant inter- and intra-molecular interactions that enhance the stability and adsorption capability of the CuL inhibitor. The successful formation of a protective layer on the surface of XC18 steel using a TMC signifies exciting prospects for the development of advanced materials with diverse applications.

Chitosan/CNDs coated Cu electrode surface has an electrical potential for electrical energy application

Polymers and nanomaterials had been widely applied at electrochemical chemosensor and biosensor. Developing technical energy is still much needed, especially using natural environmental friendly material. Both chitosan of biopolymer and carbon nanodots (CNDs) of nanomaterials are highly studied due to their extraordinary properties. The research focus on chitosan and chitosan/CNDs nanocomposite surface that was applied for electrical energy. Nanocomposite was coated on Cu electrode surface by using electroplating method. The coated electrode was dipped into oil samples. The dipped nanocomposite then was characterized by FTIR, XRD, SEM, and Chemosensor. Nanocomposite structure is still maintain its chemical compound, confirmed by FTIR and XRD, which still maintain amine group; hydroxyl group; and crystalinity of chitosan after CNDs intercoporation. Nanocomposite surface morphology show magnetite particle distribution that spreaded on the surface of electrode for both chitosan and CNDs nanocomposite, which is confirmed by SEM. The free dipping method is based on the sensitive material chitosan/CNDs as a chemosensor; the pressure process on the surface of the chitosan/CNDs sensitive material causes the interaction of metal ions and acid compounds, which involves an iontophoresis process where oil atoms that have been excited in the evaporation process will experience atomic vibrations due to electron transport which then the active groups on the Chemosensor directly absorb and bind metals and acids in oil use a chemisorption process which leads to the transfer of charge from the adsorption particles to the chemosensor surface to fill the holes so that a potential difference occurs in the form of electrical pulses which will then be captured by the Arduino system which will be converted into digital data. This process makes technological energy production in the form of electrical energy faster.

Activated Carbon derived from Jackfruit Seeds for Oil Adsorption

Activated carbons (AC) are widely used as adsorbents for treating oily wastewater. An effective, cheap and environmental-friendly method for oil adsorption by using AC derived from jackfruit seeds (JS) was developed in this study. The JS were chemically activated with different concentrations (10 wt.% and 15 wt.%) of chemical activating agents (H3PO4 and ZnCl2) to produce activated carbon. The optimum conditions for developing AC from JS with the highest oil adsorption capacity was found using 15 wt.% ZnCl2, and carbonised at 500°C resulting in maximum adsorption capacity of 0.8621 g/g. Raw JS and jackfruit seed-derived activated carbon (JSAC) were characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy analysis. The influence of process parameters such as contact times (0 – 240 minutes), adsorbent dosages (0.5 – 2.5 g) and adsorption temperatures (25 – 65 °C) for oil adsorption were investigated. The results showed that the optimum parameters for maximum adsorption capacity were as follows; 120 minutes of contact time, adsorbent dosage of 1.5 g and at 35 °C. At this condition, the highest oil adsorption capacity was achieved at 1.5674 g/g. The adsorption kinetic studies depicted that the oil adsorption mechanism was represented by pseudo-second-order kinetic model which implies that the adsorption is a chemisorption process. Jackfruit seeds had been proven to have the capability as an effective adsorbent for oil adsorption.

Insoluble Acyclic Cucurbit[n]uril-Type Receptors Capture Iodine from the Vapor Phase.

Nuclear energy makes large contributions toward meeting global energy needs, but societal concerns remain high given the impacts of the intended release of radioactive materials including 129I and 131I. In this paper we explore the use of a homologous series of acyclic CB[n] type hosts (H1 - H4) as adsorbents of iodine from the vapor phase. We find that H2 - H4, but not H1 - perform well in this application with uptake capacities of 2.2 g g-1, 1.5g g-1, and 1.9g g-1, respectively. The chemisorptive uptake process involves partial oxidation of catechol walled H2 to quinone walled host and capture of I3- and I5-. Solid H2 can be regenerated by treatment with Na2S2O4 and reused at least five times. The x-ray crystal structure of H2 is also reported.

Exploring the Effectiveness of 3-Chloro-4-morpholin-4-yl-1,2,5-thiadiazole as a Eco-Friendly Corrosion Inhibitor for Mild Steel in HCl Solution: Experimental and DFT Analysis

Corrosion is a significant issue in many industries, particularly where metals are exposed to harsh chemical environments. This study investigates the efficacy of 3-Chloro-4-morpholin-4-yl-1,2,5-thiadiazole (CMTD) as a corrosion inhibitor for mild steel in 1 M HCl solution across a temperature range of 303–333 K. Using weight loss measurements, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques, the inhibition efficiency of CMTD was evaluated at different concentrations and temperatures. The results show that CMTD achieves a maximum inhibition efficiency of 96.8% at a highest inhibitor concentration, even at elevated temperatures. The adsorption of CMTD on the mild steel surface follows the Langmuir adsorption isotherm, with a calculated free energy of adsorption (ΔGads) of -39.5 kJ/mol, confirming a spontaneous chemisorption process. Quantum chemical Density Functional Theory (DFT) studies further elucidated the relationship between CMTD's molecular structure and its inhibition efficiency. Key parameters, including the energy gap (Egap = 3.551 eV), highest occupied molecular orbital (EHOMO = -6.317 eV), and lowest unoccupied molecular orbital (ELUMO = -2.766eV), were calculated to understand CMTD's reactivity. Additionally, global reactivity descriptors such as chemical hardness (η), electronegativity (χ), and the electron fraction transferred (ΔN) from CMTD to the iron surface were analyzed. These findings suggest that CMTD is highly effective in preventing corrosion and can be applied in industries where mild steel is exposed to acidic environments, such as in petrochemical and industrial cleaning processes.

Composite biopolymer foams fabricated from natural aldehyde functionalized chitosan-whey protein amyloid fibrils: Application for removal of phthalate esters from water

In this work, composite biopolymer foams from chitosan and whey isolate protein amyloid fibrils were prepared for the removal of phthalate esters from water. Natural aldehyde functionalization enhanced the affinity for dibutyl phthalate (DBP), with citral being the most effective. The citral-grafted foams (WCGC) had tunable hydrophobicity, strong mechanical properties, and good water stability. WCGC1.5 foam exhibited a high removal efficiency (96.06 %) of DBP. The adsorption process reached adsorption equilibrium rapidly within 8 h and could be described by pseudo-second-order kinetic and Freundlich isotherm models, indicating a non-homogeneous and chemisorptive sorption process. The maximum adsorption capacity for DBP reached 332.42 mg/g. Moreover, DBP adsorption could be enhanced in alkaline environment and the removal efficiency increased to 98.27 % at pH 10. The removal efficiency of DBP by WCGC1.5 remained above 85 % after the five adsorption-desorption cycles. WCGC1.5 also showed broad-spectrum adsorption behavior, with strong affinity and removal efficiency for six common plasticizers, including DIBP (85.97 %), DPP (91.7 %), DHXP (99.1 %), DEHP (99.09 %), DNOP (91.6 %) and BBP (89.88 %).

Ternary‐Grafted Starch‐Based Hydrogel with Improved Adsorption Capacity for Dyes

AbstractBiomass‐based hydrogels can be used as the adsorbents in sewage water, as they have good adsorption capacity for heavy ions and dyes. A ternary‐grafted starch‐based hydrogel, St1.0/CMC0.5/P(AM3.0‐AA5.0‐AMPS1.0), was prepared using cornstarch (St) and sodium carboxymethyl cellulose (CMC) as raw materials, with acrylamide (AM), acrylic acid (AA), and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) as graft monomers. Due to the introduction of CMC and AMPS, the number and type of effective adsorption functional groups in the St1.0/CMC0.5/P(AM3.0‐AA5.0‐AMPS1.0) hydrogel increased, leading to an improved adsorption capacity and removal rate for methylene blue (MB). The maximum adsorption capacity and removal rate for MB could be 1624.49 mg/g and 91.8 %, respectively, at 25 °C. According to the adsorption isotherm and adsorption kinetics, the MB adsorption process on the hydrogel occurs according to the Langmuir isotherm model and quasi‐second‐order kinetics via a chemisorption process occurring on the adsorbent monolayer. Moreover, the St1.0/CMC0.5/P(AM3.0‐AA5.0‐AMPS1.0) hydrogel displayed good regeneration performance. The removal rate for MB could still achieve 84.3 % after the hydrogel was reused four times.

Adsorption of ethylene and 1-methylcyclopropene (1-MCP) on Al-doped graphene structure: A DFT study for gas sensing application

Ethylene is the ripening hormone of fruits and vegetables. 1-Methylcyclopropene (1-MCP) is used as the inhibitor of the ethylene actions for extending the postharvest shelf life of the plants. To control the ripening and extending the shelf life of the plants, the adsorption characteristics of ethylene and 1-MCP on Al-doped graphene structure (AlG) were investigated as a gas sensing application by density functional theory (DFT) calculations. The geometric structures were optimized, HOMO and LUMO, energy gap, adsorption energies, the density of states (DOS), electrostatic potential (ESP) and the global reactivities were calculated for different distances between the adsorbed ethylene or 1-MCP and the adsorbent AlG. Chemisorption and physisorption interactions were analyzed. For the chemisorption process of ethylene and 1-MCP on AlG, the adsorption energies were 19.34 kJ/mol and 56.53 kJ/mol, respectively. Whereas for the physisorption process, the adsorption energies of ethylene and 1-MCP were -60.16 kJ/mol and -7.32 kJ/mol, respectively. As a result, it was presented that the AlG structure has sufficient characteristics to be a good adsorbent and a gas sensor of ethylene and 1-MCP.

Synthesis and functional mechanism evaluation of novel polymer-graphene oxide-biochar nanocomposite for efficient removal of diethyl phthalate

Phthalates, categorized as a main constituent of endocrine-disrupting chemicals (EDCs), are present in polymeric products. These substances can enter the environment through several pathways, including improper handling, which leads to their presence in toilet water, floor washings, surface runoff, and landfill leachate. This study focuses on the performance analysis of nanocomposite materials made of polymer (polypyrrole), quasi-metal (graphene oxide), and biochar (from palmyra seed) for the elimination of diethyl phthalates (DEP) from aqueous environments. Scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) were used to describe the nanocomposite characteristics. The experimental results supported a chemisorption process by agreeing well with the pseudo-second order. The Langmuir isotherm explained the DEP sorption data, which aligned to monolayer DEP adsorption on the nanocomposite surface. With a binding affinity of −13.36 (kcal/mol) and the highest docking score, Diethyl phthalates and graphene oxide interaction is validated. The produced nanocomposite is suggested as a possible alternative for the sorption of DEP. Future applications could benefit from the higher adsorption capacity, and environmental friendliness of nanocomposites.

Development and application of a new macrocyclic ligand-functionalized mesoporous silica sorbent for selective separation of radiocesium from environmental wastewater

The growing reliance on nuclear energy and uncharacteristic accidents, such as those in Chornobyl and Fukushima, have emphasized the need for effective radiocesium (r-Cs: 137Cs) removal from environmental wastewater. This study presents the development of DFDB18C6@SBA-NH2, a novel solid-phase sorbent designed to remove r-Cs from aqueous environments selectively. The sorbent was synthesized by tethering a macrocyclic ligand, DFDB18C6 (di-formyl dibenzo-18-crown-6-ether), to amino-functionalized mesoporous SBA-15 (Santa Barbara Amorphous-15). The sorbent’s structure, thermal properties, and surface morphology were comprehensively characterized. Batch sorption experiments were performed to evaluate the influence of different operating factors on r-Cs sorption, including solution pH, contact duration, initial ion concentration, ambient temperature, and matrix ions contents. The sorption behavior was better explained with the pseudo-second-order kinetic and Langmuir isotherm models, which suggest a probable monolayer chemisorption process. The thermodynamic evaluation indicated the exothermic nature of the sorption process. The DFDB18C6@SBA-NH2 sorbent demonstrated significant 137Cs removal (approximately 85 %) from Fukushima-originated wastewater, with competing matrix ions such as Ca2+, Mg2+, Na+, and K+. These results highlight the potential of DFDB18C6@SBA-NH2 as a potential solid-phase sorbent for efficient and selective r-Cs decontamination in waste aqueous matrices.

Kinetics, Thermodynamics, and Mechanistic Studies of Arsenic Removal Utilizing Natural Soil as Adsorbent.

The contamination of water sources with the heavy metal contaminant arsenic (As) causes substantial risks to humans, animals, and other living organisms. Therefore, the introduction of methods for the removal of As is important. The present study aimed to investigate the adsorption model and mechanism of As removal utilizing natural soil adsorbents. The batch adsorption technique was used to analyze the impacts of various parameters such as contact time, initial As concentration, pH, and temperature. Adsorption mechanisms were studied through adsorption kinetic, isotherm, and thermodynamic models. The batch adsorption study findings indicate that the optimal conditions for maximum As removal were achieved by application of 2.2 g of adsorbents in 50 μg/L of As solution for 60 min of contact time at a pH of 5.5 ± 0.5 and a temperature of 40 °C. The highest removal efficiency was achieved when red soil was employed as the adsorbent. The kinetic, isotherm, and thermodynamic models revealed that As adsorption was a chemisorptive, nonspontaneous, and endothermic process.

Addressing small-scale temperature swing adsorption challenges using intensified fluidised bed technology for carbon capture process development

Polyethylenimine (PEI)-based adsorbents exhibit high CO2 capacities, making them potential candidates for mitigating unavoidable industrial CO2 emissions. However, desorption of CO2 from PEI, and from adsorbents in general, has received far less attention in the literature than adsorption. Whilst Temperature Swing Adsorption (TSA) is simple to conceptualise, it is difficult to implement in small-scale experiments in practice. Here we study the desorption characteristics of a commercial branched PEI adsorbent in a small-scale swirling fluidised bed reactor (TORBED) to improve the small-scale heat transfer rates. Our experimental results show that higher desorption temperatures, higher gas flow rates, and higher CO2 concentrations during adsorption can improve the desorption efficiency (defined as the amount of CO2 removed as a fraction of the initial amount adsorbed). In terms of kinetics, we found that the fractional order kinetic model provided the best fit to the PEI adsorbent, implying that this adsorbent involves multiple simultaneous molecular interactions, physisorption processes, and chemisorption processes, that cannot be described by simpler pseudo 1st or 2nd order models. Desorption rates in the TORBED in this study were 1 order of magnitude faster than fluidised beds, and 2–3 orders of magnitude faster than packed beds.

Response surface methodology-based optimisation of adsorption of diclofenac and treatment of pharmaceutical effluent using combined coagulation-adsorption onto nFe2O3 decorated water chestnut shells biochar.

This work involved the preparation of pristine and iron nanoparticle-loaded biochar from a water chestnut shell to remove diclofenac sodium (DCF) containing effluent of pharmaceutical origin. To create suitable forecasting equations for the modelling of the DCF adsorption onto the adsorbent, response surface methodology (RSM) was used. The parameters, e.g. pH, adsorbent mass, DCF concentration and contact time, were used for the modeling of adsorption. The RSM model predicts that for 98.0% DCF removal, the ideal conditions are pH 6, an adsorbent dose of 0.5 g L-1, and a contact time of 60 min with an initial adsorbate concentration of 25 mg L-1 at 303 K. The maximum capacity deduced from the Langmuir model was 75.9 mg g-1 for pristine water chestnut shell biochar (pWCBC) and 122.3 mg g-1 for magnetically modified nano-Fe2O3 biochar (mWCBC). Under equilibrium conditions, the Langmuir model was the best-suited model compared to the Temkin and Freundlich models. The adsorption data in this investigation efficiently fitted the pseudo-second-order model, emphasizing that chemisorption or ion exchange processes may be involved in the process. The WCBC demonstrated recyclability after 10 cycles of repeated adsorption and desorption of DCF. A combined coagulation adsorption process removed COD, NH3-N, NO3-, PO43-, and DCF by 92.50%, 86.41%, 77.57%, 84.54%, and 97.25%, respectively. This study therefore shows that coagulation followed by adsorption onto biochar can be a cost-effective substitute for conventional pharmaceutical wastewater treatment.

Turning waste into wonder: Arsenic removal using rice husk based activated carbon

In this study, rice husk activated carbon (RHAC) was synthesized by physicochemical activation, which consists of heat treatment with CO2 gasification and KOH chemical treatment to eliminate arsenic (As) from the polluted water. Initial arsenic concentrations, solution pH, solution temperature and contact time are the parameters that have been tested in this study. The characterization study showed that RHAC has a high BET surface area (815.52 m2/g) and its pore structure was found to be mesoporous with an average pore diameter of 2.96 nm. Characterization studies, including X-ray diffraction analysis (XRD), Raman spectroscopy and scanning electron microscopy (SEM) were employed to determine the RHAC’s performance. The adsorption of As towards RHAC followed the Freundlich isotherm model and pseudo-first order with adsorption process was favorable at higher arsenic concentrations. The mechanism study also signified that the adsorption of As-RHAC was limited by film-diffusion. Thermodynamic studies indicated that the As-RHAC adsorption system was endothermic, random, spontaneous, feasible in nature and governed by the chemisorption process. Desorption and regeneration studies of RHAC showed that it can be utilized up to 5 cycles and is stable for the water treatment facilities.

Adsorbtive removal of HF toxic gas via tinsulfide monolayer modification: A molecular perspective

Hydrofluoric Acid (HF) is considered one of the most hazardous chemicals used in industrial plants. Even small exposures to HF can have fatal consequences if not promptly and properly treated. Various research teams have presented numerous substances with the objective of capturing or detecting toxic HF gas. In this study, we explore the impact of HF gas on a single layer of SnS by employing density functional theory (DFT). The interaction nature between the gas molecule and the adsorbent is elucidated by analyzing the related adsorption energy, electronic structure properties and differential charge transfer. The findings indicate that HF is physically adsorbed on the pristine SnS with an adsorption energy value of −0.63 eV. By introducing a Sn mono vacancy defect, the modification of SnS enhances the adsorption energy to −1.26 eV, resulting in a chemisorption process. Molecular fluorine (F2) was discovered to undergo a barrierless reaction with SnS, resulting in the formation of fluorine-substituted SnS. It has been discovered that the substitution of fluorine atoms enhances the reactivity of SnS towards hydro-gen fluoride gas. The adsorption potential of the studied structures towards HF gas was determined to be in the following order: F2SnS > VSn–SnS > VS-SnS ∼ SnS. The current study is anticipated to offer new molecular insights that could lead to the creation of innovative devices for detecting or eliminating HF toxic gas from a specific atmosphere.