Adsorption Behavior Research Articles

Spent coffee grounds-derived carbon material as an effective adsorbent for removing multiple contaminants from wastewater: A comprehensive kinetic, isotherm, and thermodynamic study

Environmental contamination from various industrial sources poses a significant global concern, demanding effective remediation strategies. This study investigates the efficacy of spent coffee grounds-derived carbon material in removing various contaminants, including organophosphate pesticides, pharmaceutical residues, and cationic dyes from aqueous solutions. Adsorption experiments were conducted at different temperatures (25 °C, 30 °C, and 35 °C), and the adsorption behavior was analyzed using various kinetic (pseudo-first-order, pseudo-second-order, Elovich, intraparticle diffusion) and isotherm models (Freundlich, Langmuir, Temkin, Dubinin-Radushkevich). Our findings reveal a complex adsorption process involving both monolayer and multilayer adsorption on the heterogeneous surface of the material. Temperature significantly influenced adsorption behavior, affecting maximum capacities and interactions. Using a material concentration of 0.5 mg mL−1 increases adsorption capacities for both pesticides, reaching 92.0 mg g−1 for malathion and 259 mg g−1 for chlorpyrifos adsorption. At a material concentration of 0.1 mg mL−1, the carbon material exhibited high adsorption capacities for methylene blue, rhodamine B, amoxicillin, and ceftriaxone, reaching values of 2085 mg g−1, 8250 mg g−1, 82 mg g−1, and 181 mg g−1, respectively. The adsorbent was successfully regenerated using 25 % ethanol solution and reused for at least 10 cycles without significantly impacting the adsorption capacity. These results underscore the potential of spent coffee grounds-derived carbon material as an efficient adsorbent for diverse contaminants, highlighting its promising role in environmental remediation efforts.

Heavy metals remediation through alkali assisted ball-milling activation of copper smelting slag for resource utilization

This study describes the preparation of Silico-Calcium-adhesive (CS-SS) by alkali-assisted ball milling to activate copper smelting slag (CS) for the remediation of heavy metals contamination and consequent resource utilization. The adsorption behavior and mechanisms of Cd(II), Cu(II) and Pb(II) in mono-metallic and polymetallic coexisting systems were investigated. The adsorption capacities of CS-SS were 21.906mg/g, 30.893mg/g and 93.593mg/g for Cd(II), Cu(II) and Pb(II) at a pH of 6, respectively. Based on the experimental results of monometallic system indicated that CS-SS exhibited the highest adsorption capacity for Pb(II), followed by Cu(II) and Cd(II). In the polymetallic system, the inhibitory impact of Pb(II) was more potent compared to Cd(II) and Cu(II). The adsorption mechanisms included electrostatic attraction, chemical adsorption, physical adsorption, ion exchange, functional group complexation and surface precipitation. Simple economic estimates show that it costs about $4.72 to treat 1 m3 of Cd(II)-20 mg/L, Cu(II)-30 mg/L and Pb(II)-90 mg/L containing wastewater. Therefore, the CS treatment method proposed in this study has certain feasibility and economic applicability.

Interfacial hydrogen bond effect between CeO2 and g-C3N4 boosts conversion to adipic acid from aerobic oxidation of cyclohexane

The selective oxidation reaction of cyclohexane is one of the typical activated sp3 C-H reactions, and its product adipic acid (AA) is the indispensable raw material used to produce nylon. However, subjecting to the inertness of C-H bond and the great reactivity of AA, the targeted transformation of cyclohexane remains a challenge. Here, the interfacial hydrogen bond (IHD) was developed by anchoring CeO2 on graphite carbon nitride (g-C3N4) surface, which could boost targeted acquisition adipic acid from aerobic oxidation of cyclohexane. The results indicated that the IHD effect can be flexibly regulated by changing the ratio of Ce3+/Ce4+, further optimizing the properties of surface OH species and Lewis acid sites. Under the synergistic effect of Ce3+/Ce4+ and Lewis acid sites on reaction interface, the glorious performance (32.2% conversion of cyclohexane with 66.4% selectivity) was obtained over the as-prepared CeO2/g-C3N4 IHD system. In addition, the interfacial adsorption properties of cyclohexane were explored by the virtue of in situ infrared spectroscopy, revealing the IHD effect could tune the adsorption behavior of cyclohexanone and further improve the selectivity of AA. This work disclosed that engineering the interface hydrogen bond effect between CeO2 and g-C3N4 provided feasible strategies to obtain excellent catalyst for cyclohexane oxidation.

Thermodynamic Study of Adsorption behaviors of Trivalent Metal Ions onto Chelating Resin: Comparison between Scandium(III) and Other Metal Ions

Thermodynamic Study of Adsorption behaviors of Trivalent Metal Ions onto Chelating Resin: Comparison between Scandium(III) and Other Metal Ions

Preparation of biomass carbon dots/carboxymethyl cellulose-based fluorescent hydrogel: Combines selective detection and visual adsorption for Copper(II)

Abstract In this study, we used nitrogen-doped carbon dots (NCDs), which were synthesized via the hydrothermal method of corn-stover biomass as raw material and polyethyleneimine (PEI) as the nitrogen source, introduced them into the carboxymethyl cellulose-based hydrogel to prepare an environmentally friendly fluorescent cellulose-based hydrogel (NCDs/CMC-PAM). NCDs/CMC-PAM was also used for simultaneous fluorescence monitoring and removal of Cu (II) in aqueous solution. The chemical and physical structures, adsorption behaviors and fluorescent properties of NCDs/CMC-PAM were investigated. The results showed that NCDs/CMC-PAM exhibited a well-linear response range of fluorescence response for Cu (II) (0∼100 μM, detection limit of 3.42 μM). NCDs/CMC-PAM showed maximum adsorption capacities of 237.71 mg/g for Cu (II), the adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetic model, which is an exothermic spontaneous reaction with an increase in entropy. It can still maintain 79.03% of the original adsorption capacity after six cycles (pH=6). The adsorption mechanisms of NCDs/CMC-PAM for Cu (II) are intraparticle diffusion, electrostatic attraction, ion exchange, and ligand interaction. Hence, the present study provides a new green way to synthesize an adsorbent that can be applied for the adsorption and detection of heavy metal ions.

Tailoring the electronic structure of Fe–N4 sites via heteroatom modification strategy for boosting oxygen reduction in hydrogen fuel cells: A density functional theory study

Heteroatoms-modified Fe–N–C catalysts have garnered significant attention for enhancing the oxygen reduction reaction (ORR). However, revealing the correlation between the type of heteroatoms used for doping and catalytic performance still faces significant challenges. Herein, based on the density functional theory (DFT), a series of heteroatom-modified Fe–N–C models with the tailored Fe–N4-X (X = S, P or B) site are constructed to explore the regulatory mechanism of heteroatoms on the electronic structure and adsorption behavior of Fe centers. Theoretical calculations reveal that the doping of S atoms can optimize the electronic environment of Fe atoms, thus leading the favorable interaction between Fe–N4–S site and OH intermediates. As a result, the Fe–N4–S site possess a lower energy barrier for the desorption of OH* than that of Fe–N4–B and Fe–N4–P, indicating higher catalytic activity and kinetics of S-modified Fe–N–C catalysts.

Neodymium (III)-containing poly(lactide-co-glycolide)-coated robocast bioactive glass scaffolds for photothermal therapy and bone regeneration

In this study, trivalent neodymium-doped silicate-based 13–93 bioactive glass scaffolds were prepared by the robocasting method using sol-gel-derived bioactive glass powders for tissue engineering applications. Sintered scaffolds were coated by borate-based 13-93B3 bioactive glass-containing polylactide-co-glycolide solution. The produced composite scaffolds’ mechanical, morphological, and structural characteristics were thoroughly examined, as their in vitro bioactivity in cell culture media and simulated body fluid. Furthermore, the scaffolds’ amoxicillin adsorption and release behavior was examined over time. The outcomes demonstrated that it was feasible to effectively create periodic, mesh-like-patterned robocast glass scaffolds utilizing Nd3+-doped sol-gel-derived bioactive glass powders. The scaffolds’ compressive strengths ranged from 10.02 MPa to 18.6 MPa, with the PLGA-coated scaffolds exhibiting the highest strength values. All of the scaffolds that were submerged in simulated body fluid for 28 days showed hydroxyapatite formation. The presence of borate glass on the surface of the silicate-based glass scaffolds improved the hydroxyapatite formation ability. The quantity of drug adsorption for all types of scaffolds was measured to be between 4 and 9% whereas the cumulative drug release was in the range of 58 to 96%. Borate glass particle-containing PLGA coating enhanced the drug delivery behavior.

Adsorption behavior of NH4+ and Mg2+ at kaolinite surfaces: Effect of the ion concentration, NH4+/Mg2+ mixing ratio, and layer charge

AbstractThe adsorption behavior of NH4+ and Mg2+ at kaolinite surfaces was investigated by using molecular dynamics (MD) simulations, considering the factors such as ion concentration, NH4+/Mg2+ mixing ratio, and layer charge of kaolinite. The results showed that the increase in ion concentration did not affect the adsorption modes of NH4+ and Mg2+ ions but promote the increase in the adsorption capacity. The total adsorption capacities of Mg2+ and NH4+ were 3.25 × 10−6 and 2.85 × 10−6 μmol·mm−2 at the ion concentration of 1.5 mol·L−1, respectively. When NH4+ and Mg2+ were co‐adsorbed, they could inhibit the adsorption of each other at the surface of kaolinite, except that the inner‐sphere (IS) adsorption of NH4+ at aluminum hydroxyl (Al–OH) surface could be enhanced by the presence of Mg2+. Both NH4+ and Mg2+ tended to adsorb at the siloxane (Si–O) surface of kaolinite rather than Al–OH surface. When layer charge occurred in kaolinite, a small number of Mg2+ began to adsorb in the IS complexes at 1.7 and 2.3 Å above the Al and O atoms of the lattice‐substituted tetrahedra of the Si–O surface, and at 1.7 Å above the hexahedra of the Al–OH surface. However, most of NH4+ were adsorbed in IS complexes at 1.7 Å above the center of the oxygen six‐membered ring of the Si–O surface and above the hexahedron of the Al–OH surface. The adsorption capacity of Mg2+ changed little with the increase of layer charge density, while the IS and total adsorption capacity of NH4+ increased significantly.

Characterizing Macroporous Ion Exchange Membrane Adsorbers for Natural Organic Matter (NOM) Removal—Adsorption and Regeneration Behavior

Addressing the characterization of Natural Organic Matter (NOM) removal by functionalized membranes in water treatment, this study evaluates the effectiveness of two commercial ion-exchange membrane adsorbers: Sartobind® Q (with quaternary amines) and D (with tertiary amines). Using Suwannee River NOM (SRNOM) as a surrogate, Langmuir adsorption isotherms revealed maximum capacities (Qmax) of 2966 ± 153 mg C/m2 and 2888 ± 112 mg C/m2, respectively. Variations in flux from 50 to 500 LMH had a minimal impact on breakthrough times, proving low diffusion limitations. The macroporous (3–5 µm) functionalized cellulose-based membranes exhibited high permeabilities of 10800 L/(h m2 bar). Q maintained positive zeta potential vs. pH, while D’s zeta potential decreased above pH 7 due to amine deprotonation and turning negative above an isoelectric point of 9.1. Regeneration with 0.01 M NaOH achieved over 95% DOC regeneration for Sartobind® D, characterizing reversibility through a pH-swing. Cyclic adsorption showed that Q maintained its capacity with over 99% DOC regeneration, while D required acidic conditioning after the first regeneration cycle to mitigate capacity reduction and re-deprotonate the adsorber. These results have demonstrated the potential suitability of adsorber membranes, designed originally for biotechnological purposes, for the possible removal of disinfection byproduct precursors in drinking water treatment.

Cation-Modified Poly(vinyl alcohol) Film to Optimize the Bistability of Transparent Electrophoretic Display Based on Charge Adsorption Behavior in Nonpolar Solvent.

Electrophoretic displays (EPDs) utilize the electrophoretic particles in electronic ink (e-ink) to display different color states with bistability. Bistability of EPDs is achieved by placing colloidal particles in a highly viscous solvent to keep the distribution of colloidal particles stable without sustaining the external field, so it only consumes power when updating the image. The feature of low power consumption makes it suitable for applications such as advertising boards, price tags, etc. Apart from these applications, recent research on lateral-driving EPDs extends its applications to smart windows, privacy control, and so on. However, achieving bistability by simply increasing the viscosity of solvent is inefficient in the case of lateral driving operation. Therefore, it is deserving to have intensive study on the mechanism of bistability from other aspects. Herein, we propose a mechanism to investigate the charge adsorption behavior on the electrode to affect the bistability of particles, which is based on the "Stern layer adsorption/desorption" model. Based on the above mechanism, we further fabricated a hexadecyl trimethylammonium bromide (CTAB)/poly(vinyl alcohol) (PVA) composite film on the electrode to improve the bistability of lateral-driving EPD by reducing the diffusion current caused by unabsorbed charges. This developed lateral-driving EPD can significantly improve the bistability, which is enhanced from 40 s to 7 min, an increase by a factor of approximately 10. This work gives a way to consider the bistability of colloidal particles in nonpolar solvent.

Liquid-Phase Adsorption Behavior of β-D-Glucooligosaccharides When Using Activated Carbon for Separation, and the Antioxidant Stress Activity of Purified Fractions

The adsorption characteristics of β-glucooligosaccharides on activated carbon and the purification were systematically investigated. The maximum adsorption capacity of activated carbon reached 0.419 g/g in the optimal conditions. The adsorption behavior was described to be monolayer, spontaneous, and exothermic based on several models’ fitting results. Five fractions with different degrees of polymerization (DPs) and structures of β-glucooligosaccharides were obtained by gradient ethanol elution. 10E mainly contained disaccharides with dp2a (G1→6G) and dp2b (G1→3G). 20E possessed trisaccharides with dp3a (G1→6G1→3G) and dp3b (G1→3G1→3G). 30E mainly consisted of dp3a and dp4a (G1→3G1→3(G1→6)G), dp4b (G1→6G1→3G1→3G), and dp4c (G1→3G1→3G1→3G). In addition to tetrasaccharides, 40E and 50E also contained pentasaccharides and hexasaccharides with β-(1→3)-linked or β-(1→6)-linked glucose residues. All fractions could inhibit the accumulation of intracellular reactive oxygen species (ROS) in H2O2-induced Caco-2 cells, and they could improve oxidative stress damage by increasing the activity of superoxide dismutase (SOD) and reduced glutathione (GSH), which were related to their DPs and structures. 50E with high DPs showed better anti-oxidative stress activity.

Efficient Electrosynthesis of Urea over Single-Atom Alloy with Electronic Metal Support Interaction.

Urea electrosynthesis from carbon dioxide (CO2) and nitrate (NO3-) is an alternative approach to traditional energy-intensive urea synthesis technology. Herein, we report a CuAu single-atom alloy (SAA) with electronic metal support interaction (EMSI), achieving a high urea yield rate of 813.6 μg h-1 mgcat-1 at -0.94 V versus reversible hydrogen electrode (vs. RHE) and a Faradaic efficiency (FE) of 45.2% at -0.74 V vs. RHE. In-situ experiments and theoretical calculations demonstrated that single-atom Cu sites modulate the adsorption behavior of intermediate species. Bimetallic sites synergistically accelerate C-N bond formation through spontaneous coupling of *CO and *NO to form *ONCO as key intermediates. More importantly, electronic metal support interaction between CuAu SAA and CeO2 carrier further modulates electron structure and interfacial microenvironment, endowing electrocatalysts with superior activity and durability. This work constructs SAA electrocatalysts with EMSI effect to tailor C-N coupling at the atomic level, which can provide guidance for the development of C-N coupling systems.

Efficient Electrosynthesis of Urea over Single‐Atom Alloy with Electronic Metal Support Interaction

Urea electrosynthesis from carbon dioxide (CO2) and nitrate (NO3−) is an alternative approach to traditional energy‐intensive urea synthesis technology. Herein, we report a CuAu single‐atom alloy (SAA) with electronic metal support interaction (EMSI), achieving a high urea yield rate of 813.6 μg h−1 mgcat−1 at –0.94 V versus reversible hydrogen electrode (vs. RHE) and a Faradaic efficiency (FE) of 45.2% at –0.74 V vs. RHE. In‐situ experiments and theoretical calculations demonstrated that single‐atom Cu sites modulate the adsorption behavior of intermediate species. Bimetallic sites synergistically accelerate C‐N bond formation through spontaneous coupling of *CO and *NO to form *ONCO as key intermediates. More importantly, electronic metal support interaction between CuAu SAA and CeO2 carrier further modulates electron structure and interfacial microenvironment, endowing electrocatalysts with superior activity and durability. This work constructs SAA electrocatalysts with EMSI effect to tailor C‐N coupling at the atomic level, which can provide guidance for the development of C‐N coupling systems.

Optimization of Hydrochar Production from Cigarette Filters for Enhanced CO2 Adsorption

In this study, CO2 capture using Hydrochar adsorbents synthesized from Cigarette Filter, specifically H-208 and HA-204, was rigorously investigated. Optimization using RSM was applied to fit a quadratic model to the data with F-value of 184.95 and R2 of 0.9847. H-208 and HA-204 display maximum CO2 adsorption capacities of 1028.35 mg/g and 1003.35 mg/g, respectively, at 9 bar and 25°C. Isotherm studies ranked Freundlich and Sips models as effective descriptors, highlighting differences in adsorption behavior between HCs synthesized at different conditions. Kinetic modeling identified the Elovich model as suitable for predicting time-dependent CO2 adsorption. Thermodynamic analysis revealed differences in adsorbent affinity and spontaneity between HCs, with higher enthalpy values for H-208 indicating stronger adsorbent-adsorbate interactions. ΔH° values of -61.863 KJ/mol for H-208 and -47.442 KJ/mol for HA-204, signifying an exothermic adsorption process. The CO2 adsorption mechanism involves physical and chemical processes influenced by the polar structure, surface area, and functional groups of HCs. The effect of HCl on CO2 adsorption is insignificant, and the use of HCl only reduces the synthesis time. Adsorbent reusability tests showed minor capacity declines over multiple cycles, indicating their potential in environmental remediation and industrial gas separation processes.

Covalent crosslinking tetraethylenepentamine/cellulose composite aerogels with adsorbability for dyes elimination

The cellulose-biomass material possesses a distinctive structure, distinguished by its eco-friendliness, degradability, renewability, cost-effectiveness, and efficacy as a bio-absorbent. In this groundbreaking study, we synthesized cellulose aerogels for the first time using a combination of sol-gel processing, straightforward chemical crosslinking, and freeze-drying. The functionalized materials exhibit an intricately interconnected three-dimensional porous structure achieved through covalent crosslinking with tetraethylenepentamine (TEPA). The resulting aerogel demonstrated a highly porous structure (exceeding 90%), low density (91.89-114.87 mg/cm3), and abundant surface amine groups advantageous for removing organic dyestuffs. To comprehensively assess the impact of the fabricated aerogel on methylene blue and crystal violet adsorption behavior, a detailed investigation was conducted, considering variables such as cellulose content (1.0-3.0 wt%), TEPA/EtOH/H2O volume ratio (1.0-3.0/5.0/3.0), contact time (0-300 mins), and initial dye concentration (25-200 mg/L). As a result, the nitrogen-rich aerogel (with 2 wt% cellulose and TEPA/EtOH/H2O ratio of 2.0/5.0/3.0) exhibited dye adsorption following a pseudo-second-order kinetic model, with adsorption isotherms aligning with the Freundlich model. Thermodynamic assessments indicated that the adsorption process is a spontaneous endothermic reaction. Consequently, these eco-friendly cellulose sponges emerge as promising adsorbents for effective wastewater treatment, highlighting their potential as a sustainable solution in environmental remediation.

Preparation and Application of Responsive Nanocellulose Composites

Cellulose nanofibrils/poly(N-Isopropylacrylamide) semi-interpenetrating networks (MMCNF-PNAs) were synthesized using an in situ fabrication (semi-IPN). The polymerization of N-isopropylacrylamide (NIPAM) (free radical) was conducted in the presence of magnetic modified cellulose nanofibrils (MMCNFs). The adsorption behaviors and surface morphology of the synthesized adsorbents were investigated systematically. The adsorption behaviors of the as-prepared MMCNF-PNA towards methylene blue (MB, as the model contaminant) dye was studied, and the optimal adsorption conditions were also studied. The adsorption processes could be well fitted using pseudo-second-order and Elovich kinetic models. Meanwhile, Langmuir and Freundlich isotherm models were used to fit the adsorption which occurred at 25, 37 and 65 °C. The corresponding results showed that the Freundlich isotherm model fitted the adsorption process better, indicating that the dye’s adsorption happened via heterogeneous adsorptive energies on the prepared MMCNF-PNAs. Their desorption and reusability were also studied to verify magnetic responsivity. To sum up, MMCNF-PNAs are promising magnetic and thermal stimuli-responsive adsorbents, showing a controlled adsorption/desorption process.

Removal of reactive black 5 in water using adsorption and electrochemical oxidation technology: kinetics, isotherms and mechanisms

AbstractIn this work, a novel graphite intercalation compound (GIC) particle electrode was used to investigate the adsorption of Reactive Black 5 (RB5) and the electrochemical regeneration in a three-dimensional (3D) electrochemical reactor to recover its adsorptive capacity. Various adsorption kinetics and isotherm models were used to characterise the adsorption behaviour of GIC. Several adsorption kinetics were modelled using linearised and non-linearised rate laws to evaluate the viability of the sorption process. Studies on the selective removal of RB5 dyes from binary mixture in solution were evaluated. RSM optimisation studies were integrated with ANOVA analysis to provide insight into the significance of selectivity reversal from the salting effect of textile dye solution on GIC adsorbent. A unique range of adsorption kinetics and isotherms were used to evaluate the adsorption process. Non-linear models best simulated the kinetic data in the order: Elovich > Bangham > Pseudo-second-order > Pseudo-first-order. The Redlich–Peterson isotherm was calculated to have a dye loading capacity of 0.7316 mg/g by non-linear regression analysis. An error function analysis with ERRSQ/SSE of 0.1390 confirmed the accuracy of dye loading capacity predicted by Redlich–Peterson isotherm using non-linear regression analysis. The results showed that Redlich–Peterson and SIPS isotherm models yielded better fitness to experimental data than the Langmuir type. The best dye removal efficiency achieved was ~ 93% using a current density of 45.14 mA/cm2, whereas the highest TOC removal efficiency achieved was 67%.

First-principles study of hydrogen sulfide decomposition on Sc-Ti3C2O2 single-atom catalyst.

Hydrogen sulfide gas poses significant risks to both human health and the environment, with the potential to induce respiratory and neurological effects, and a heightened fatality risk at elevated concentrations. This article investigates the catalytic decomposition of H2S on a Sc-Ti3C2O2 single-atom catalyst(SAC) using the density functional theory-based first-principles calculation approach. Initially, the adsorption behavior of H2S on Ti3C2O2-MXene was examined, revealing weak physical adsorption between them. Subsequently, the transition metal atom Sc was introduced to the Ti3C2O2 surface, and its stability was studied, demonstrating high stability. Further exploration of H2S adsorption on Sc-Ti3C2O2 revealed direct dissociation of H2S gas molecules into HS* and H*, with HS* binding to Sc and H* binding to O on the Ti3C2O2 surface, resulting in OH groups. Using the transition state search method, the dissociation of H2S molecules on the SAC's surface was investigated, revealing a potential barrier of 2.45eV for HS* dissociation. This indicates that the H2S molecule can be dissociated into H2 and S with the action of the Sc-Ti3C2O2 SAC. Moreover, the S atom left on the catalyst surface can aggregate to produce elemental S8, desorbing on the catalyst surface, completing the catalytic cycle. Consequently, the Sc-Ti3C2O2 SAC is poised to be an efficient catalyst for the catalytic decomposition of H2S. The Dmol3 module in Materials Studio software based on density functional theory is used in this study. The generalized gradient approximation method GGA-PBE is used for the exchange-correlation function. The complete LST/QST and the NEB methods in the Dmol3 module were used to study the minimum energy path of the dissociation of hydrogen sulfide molecules on the catalyst surface.

Structural Characterisation of Zeolites Derived from Lithium Extraction: Insights into Channel- and Cage-Type Frameworks

This study investigates the structural and adsorption characteristics of channel- and cage-type zeolites obtained through lithium extraction. Through XRD, FT-IR spectroscopy, and adsorption isotherm analyses, distinct adsorption behaviours of CH4 and CO2 were observed in both zeolite types. Cage-type zeolites exhibited higher adsorption capacities attributed to their structural advantages, highlighting the importance of structural framework selection in determining adsorbent efficacy. The presence of structural defects and an amorphous phase influenced adsorption behaviours, while thermodynamic data underscored the role of adsorbate properties. Kinetics studies revealed the influence of the structural framework on CH4 adsorption and CO2 adsorption kinetics. Analysis of adsorbate–adsorbent interactions demonstrated robust interactions, particularly with LPM16-Y. These findings offer insights into the potential applications of zeolites in gas adsorption processes, emphasising the importance of structural properties and adsorbate characteristics in determining adsorption performance.

Efficient Removal of Nickel from Wastewater Using Copper Sulfate-Ammonia Complex Modified Activated Carbon: Adsorption Performance and Mechanism.

The necessity to eliminate nickel (Ni) from wastewater stems from its environmental and health hazards. To enhance the Ni adsorption capacity, this research applied a copper sulfate-ammonia complex (tetraamminecopper (II) sulfate monohydrate, [Cu(NH3)4]SO4·H2O) as a modifying agent for a Phragmites australis-based activated carbon preparation. The physiochemical properties of powdered activated carbon (PAC) and a modified form ([Cu(NH3)4]-PAC) were examined by measuring their surface areas, analyzing their elemental composition, and using Boehm's titration method. Batch experiments were conducted to investigate the impact of various factors, such as Ni(II) concentration, contact time, pH, and ionic strength, on its substance adsorption capabilities. Additionally, the adsorption mechanisms of Ni(II) onto activated carbon were elucidated via Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The findings indicated that modified activated carbon ([Cu(NH3)4]-PAC) exhibited a lower surface area and total volume than the original activated carbon (PAC). The modification of PAC enhanced its surface's relative oxygen and nitrogen content, indicating the incorporation of functional groups containing these elements. Furthermore, the modified activated carbon, [Cu(NH3)4]-PAC, exhibited superior adsorption capacity relative to unmodified PAC. Both adsorbents' adsorption behaviors conformed to the Langmuir model and the pseudo-second-order kinetics model. The Ni(II) removal efficiency of PAC and [Cu(NH3)4]-PAC diminished progressively with rising ionic strength. Modified activated carbon [Cu(NH3)4]-PAC demonstrated notable pH buffering and adaptability. The adsorption mechanism for Ni(II) on activated carbon involves surface complexation, cation exchange, and electrostatic interaction. This research presents a cost-efficient preparation technique for preparing activated carbon with enhanced Ni(II) removal capabilities from wastewater and elucidates its underlying adsorption mechanisms.