Adsorption Equilibrium Research Articles

Synthesis of Multivalent Glycoside-Immobilized Carboxymethyl Cellulose Nanohydrogel Particles with Superadsorption Ability for Lectins.

Carboxymethyl cellulose (CMC) is a water-soluble cellulose derivative that is nontoxic, biocompatible, biodegradable, and nonallergenic. As developing an adsorbent material for carbohydrate-binding proteins is challenging, we aimed to synthesize CMC nanohydrogel particles (CMCGPs) with an extremely high lectin adsorption tendency in this study. CMCGPs were used as the backbone of an adsorption carrier that was synthesized by cross-linking CMC with ethylene glycol diglycidyl ether. A series of glycoside-immobilized CMCGPs were synthesized by binding two types of glycans (LacNAc and lactose) to the polyvalent carboxymethyl groups that are present on the CMCGP surface and act as reaction sites. These immobilized glycosides function as molecular recognition sites. Glycan moieties were incorporated into the CMCGP backbone at degrees of immobilization (DI) ranging from 8.7 to 21.0% by altering the reaction composition. LacNAc-CMCGP (3b) showed a 19.9% DI of LacNAc glycoside to the CMCGP carboxymethyl group; on average, its particle size swelled to 418 nm in phosphate-buffered saline, which is approximately 1.4 times its dry-state size. Analyzing the adsorbent properties of glyco-CMCGPs using a lectin-binding assay showed the high structural specificity of glyco-CMCGPs to lectins. The equilibrium isotherm data was explained by the Langmuir adsorption model. Notably, compound 3b adsorbed 1.95 ± 0.05 μg of wheat germ agglutinin (WGA) lectin per 1.0 μg-dry of 3b particles at an adsorption equilibrium time of a few minutes. Furthermore, solid-state 13C nuclear magnetic resonance analysis showed that WGA lectin retained its natural structure without denaturation after binding to LacNAc-CMCGP. These results were also supported by affinity purification experiments of WGA from raw wheat germ extract using LacNAc-CMCGP, demonstrating that glyco-CMCGP is capable of adsorbing and desorbing lectin while maintaining its biological activity. Thus, multivalent glycoside-immobilized CMCGPs that use woody biomass derivatives as the backbone are expected to be applied as biorefinery materials, which specifically and abundantly adsorb not just plant lectins but also pathogenic viruses and toxin proteins.

Enhanced Hydrophilicity of DAAQ-TFP COFs via Sulfonate Modification for Air Water Harvesting in Arid Environment.

The poor ability of covalent organic frameworks (COFs) based adsorbents at low relative humidity (RH) conditions limits their applications for air-water harvesting in arid environments. In the present work, the sulfonated COFs (DAAQ-TFP-SO3H@LiCl) composites are prepared through the functionalization of sulfonic acid and LiCl composite to improve its hydrophilicity. TheDAAQ-TFP-SO3H@LiCl composites exhibit a good adsorption performance, outperforming many other COF adsorbents developed so far. It can absorb 0.22±0.005g g-1 and 1.01±0.027g g-1 of water at room temperature under 20% RH and 90% RH, respectively while demonstrating good cyclic stability. Compared with the isotherm of the DAAQ-TFP, the introduction of the sulfonic acid group shifts the inflection point of the water isotherm toward low humidity, indicating that the sulfonic acid group effectively expends the working humidity range of the adsorbent and enables the effective water adsorption in an arid environment. Furthermore, the DAAQ-TFP-SO3H@LiCl composites display rapid kinetics during both the adsorption and desorption processes, reaching saturation within 60min in the equilibrium adsorption test and completing desorption within 12min at 50°C. This innovative approach provides a new method for designing adsorbent materials with low energy input requirements and high daily water consumption capabilities.

Facile preparation of NiFe2O4 decorated chitosan-graphene oxide for efficient remediation of Co(II) and adsorption mechanism

In the background of severe water pollution, adsorption is a charming technique for heavy metal remediation. In this work, NiFe2O4 decorated chitosan-graphene oxide (NFCG) was prepared by simple hydrothermal method for Co(II) remediation application. Adsorption mechanism was elaborately elucidated based on multiple evidences extracted from adsorption fitting (isotherms, thermodynamics and kinetics), spectroscopic test (XPS, UV–Vis absorption, fluorescent emission and Raman spectra) and the hard-soft acid-base (HSAB) theory inspection. Result shows, for Co(II) with initial concentration 200 mg·L−1, NFCG with dosage 500 mg·L−1 reaches adsorption equilibrium in 24 min, rendering removal percentage and adsorption amount 96.87 % and 387.48 mg·g−1, respectively. Owing to the efficient recovery enabled by paramagnetism, NFCG keeps adsorption amount 311.01 mg·g−1 for Co(II) after six consecutive cycles. Moreover, NFCG exhibits selectivity towards Co(II) under the coexistence of common interfering substances. Adsorption fitting suggests chemical adsorption based on heterogeneous affinity. Spectroscopic analysis discloses, CO, CO, -C(=O)NH-, OH and aromatic part contribute to Co(II) adsorption via electron donation, forming CoO bond. This atomic scale adsorption mechanism was substantiated by HSAB theory calculation. In brief, this work provides basic knowledge and technical support for fabricating high efficiency magnetic bio adsorbent.

A facile and green synthesis of corn cob-based graphene oxide and its modification with corn cob-K2CO3 for efficient removal of methylene blue dye: Adsorption mechanism, isotherm, and kinetic studies

In recent years, the treatment of synthetic dyes has become an environmental concern. In this study, a single step calcination process was used to develop the inventive, simple, and inexpensive adsorbent CC-GO/CC-K2CO3 composite. The composite was employed for the treatment of methylene blue (MB), a cationic dye. Several characterization methods including powder XRD, FTIR, XPS, BET, FESEM, EDX, Raman, and HRTEM techniques were utilized for the analysis of the composite. The surface area and mean pore diameter of CC-GO/CC-K2CO3 were 32.651 m2 g−1 and 3.71 nm, respectively. The adsorption experiment showed that optimal parameters for the removal of MB dye are at an adsorbent dose of 60 mg, initial dye concentration of 80 mg/L, contact time of 150 min, and pH value of 12 at room temperature. Under optimized conditions, CC-GO evidences a removal efficiency of 70.34 ± 1.36 % while after incorporation with CC-K2CO3 the removal capacity sharply increases up to 98.10 ± 0.4 %. Kinetic and isotherm models were used to analyze the removal rate constant and equilibrium adsorption capacity under various adsorption environments. The adsorption study was found to follow the models of pseudo-second order kinetic and Freundlich isotherm. The CC-GO/CC-K2CO3 composite has the maximum adsorption capacity (MAC) of 160.77 mg/g established by the Langmuir isotherm. The prepared composite has demonstrated the capacity to be recycled up to three times with a gradual decrease in its adsorption behavior, exhibiting removal efficiency of 61.66 ± 2.04 %.A cost estimation study of the composite was also performed to assess its cost effectiveness.

Consecutive Regulation of H* Adsorption Equilibrium via Selenium-Enriched Engineering for Boosted Photocatalytic Hydrogen Evolution

Consecutive Regulation of H* Adsorption Equilibrium via Selenium-Enriched Engineering for Boosted Photocatalytic Hydrogen Evolution

Sunlight-Driven Photodegradation of RB49 Dye Using TiO2-P25 and TiO2-UV100: Performance Comparison

By combining measurements of photocatalysis under solar irradiation with measurements of total organic carbon, we have compared the performance of two TiO2-based photocatalysts in the photodegradation of the dye Reactive Blue 49 (RB49). TiO2-P25 and TiO2-UV100 commercial photocatalysts were tested within a concentration ranging from 0.5 to 4 g/L. The dye solution concentration was varied from 10 to 50 mg/L and its pH was increased from 3 to 9. Extensive characterization of the photocatalysts was performed using Fourier-transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. TiO2-UV100 proved to be more active in adsorbing RB49 dye than TiO2-P25. At low dye concentrations, the adsorption equilibrium is reached in 15 min. This time increases to 1 h at higher concentrations. The photocatalytic degradation of aqueous RB49 under sunlight was monitored by UV-Vis spectrophotometry. The apparent rate constant of dye photodegradation with TiO2-UV100 is twice that of TiO2-P25. The total organic carbon (TOC) analysis showed a removal of around 98% with TiO2-UV100 and only 85% with TiO2-P25 after 3 h of solar irradiation. Over five photocatalytic cycles of 3 h, TiO2-UV100 maintained a more stable and higher efficient photocatalytic performance. All our results converge toward a better photocatalytic performance of TiO2-UV100 for the photodegradation of RB49 dye and indicate that the most decisive factor is its greater capacity to adsorb the pollutant.

Synthesis of magnetic chitosan-composite biochar and its removal of copper ions (Cu2+) and methylene blue (MB) dye from aqueous solutions.

This study presents the synthesis and evaluation of a magnetic chitosan-modified biochar (M-BC-CS) composite, developed from waste maize straw, for the efficient removal of copper ions (Cu2+) and methylene blue (MB) dye from aqueous solutions. The composite was characterized using advanced techniques such as SEM, BET, FTIR, XPS, and XRD, confirming its enhanced surface area, porosity, and magnetic properties. The study is aimed at investigating the optimal conditions for adsorption of Cu2+ and MB by M-BC-CS through analysis of the influence of diverse adsorbent dosages, pH levels, reaction times, and initial solution concentrations. The findings demonstrated that the equilibrium duration for the adsorption of Cu2+ and MB by M-BC-CS was 60min, resulting in corresponding equilibrium adsorption quantities of 54.42mg/g and 67.23mg/g, respectively. To elucidate the adsorption mechanism, the present investigation applied the pseudo-second-order kinetic model and the Langmuir isotherm. The outcomes suggested that the adsorption process is attributable to single molecular layer chemisorption. XPS and FTIR analysis determined that ion exchange and electrostatic interactions are the predominant mechanisms responsible for the simultaneous adsorption of Cu2+ and MB, and a competitive relationship exists between these mechanisms. In addition, M-BC-CS exhibited exceptional magnetic separation performance, enabling effortless and effective separation when exposed to an external magnetic field. Furthermore, the results demonstrated that M-BC-CS has good reusability and high adsorption capacity also in real wastewater, thus emphasizing its potential as a promising adsorbent for the elimination of Cu2+ and MB from aqueous solutions.

Use of Brushite as Adsorbent for the Removal of Anionic and Cationic Dyes Present in Aqueous Solutions

Currently, water pollution caused by dyes is a serious problem since they are toxic and carcinogenic to living beings. To reduce the presence of these contaminants, natural adsorbents have been considered as they are easy to obtain, inexpensive, and have high removal efficiency. In this work, the adsorption process using natural brushite (nDCPD) was studied for the removal of phenol red (PR), achieving a removal rate of 99.15% and an adsorption capacity of 82.24 mg/g, and gentian violet (GV), achieving a removal rate of 97.03% and an adsorption capacity of 74.22 mg/g. Equilibrium adsorption occurs for both dyes in multiple layers on the surface. The adsorption process is spontaneous for both dyes. The kinetics of the adsorption process involve using a single active site on the surface for PR adsorption, while for GV, two active sites on the surface are required. Analysis via FTIR, EDS, and XRD revealed various mechanisms that intervene in the adsorption process of both dyes on the surface of nDCPD, such as electrostatic forces, functional groups, physisorption, and ion exchange.

Metal-modified biochars prepared from blue algae and their ability of adsorbing phosphates from water and utilization as soil amendment

The problem of blue algae accumulation can be alleviated by utilizing blue algae as biomass for resource utilization, which can remove excess phosphates from water to alleviate eutrophication. Herein, Magnesium (Mg) and/or lanthanum (La) were used to modify biochar via high-temperature slow pyrolysis with blue algae as the raw biomass. These modified biochars exhibited abundant carbon (18.0%-50.3%), oxygen content (17.4%-49.1%), along with a high specific surface area (82.26-233.80 m2/g). The surface of metal-modified biochar was enriched with hydroxyl and carboxyl groups and metal elements were efficiently incorporated into biochars. Adsorption kinetic and isotherm experiments were conducted under the optimal pyrolysis temperature of 600 °C, pH of 6.0, and adsorbent dosage of 2.0g/L. The adsorption kinetics studies by metal-modified biochars for phosphate fitted well pseudo-second-order model Redlich-Peterson isotherm model. Biochar modified by Mg and La exhibited the highest removal efficiency (97.8%) for phosphate at adsorption equilibrium. The adsorption mechanism involved the electrostatic interaction between hydroxylated metal oxides and negatively charged phosphate ions and the precipitation of phosphate ions through chemical reactions with metal oxides in the solution. After phosphate adsorption, the pristine and metal-modified biochars derived from blue algae were applied as the soil amendment. Biochar adsorbed phosphate apparently improved the germination rate of seeds facilitated the height, width, weight, and chlorophyll content of vegetable seedlings, and induced oxidative stress, which proved that the biochar recovered after adsorption was a high-quality soil amendment. This study provides a new approach for the treatment of phosphate wastewater and the algae application.

Simple and efficient enrichment and separation of glycoprotein by teamed boronate affinity magnetic carbon nanospheres

Protein glycosylation is a key regulatory mechanism that controls many physiological and pathological processes. Analyses of glycoproteins in biological samples require challenging enrichment steps in light of sample complexity and low glycoprotein abundance. Here, in order to develop an efficient method to enrich glycoproteins, a magnetic carbon nanospheres (MCs) rich in amino group and polyboric acid sites was designed and prepared. The teamed boronate affinity was formed by the self-assembled of amino group and boric acid, which can specifically capture glycoprotein containing cis-diol under neutral conditions. Firstly, a simple green hydrothermal method led to the production of a carbon nanospheres matrix with abundant surface hydroxyl and carboxyl moieties. Then, MCs were synthesized by solvothermal method. Subsequently, the MCs were modified with polyethyleneimine and boric acid in turn to obtain the proposed composite. The hydrophilicity of amino group and its hydrogen bond with glycoprotein, as well as the cyclization reaction of boric acid with cis-1,2-diol, are utilized to specifically bind to glycoprotein. The prepared magnetic nanospheres exhibited binding to glycoproteins with rapid kinetics and strong affinity. Adsorption equilibrium was reached within 40 min, and the adsorption capacities for the glycoproteins ovalbumin, transferrin and horseradish peroxidase were found to be 493, 346 and 326 mg/g, respectively, while the adsorption capacities for the non-glycoproteins bovine serum protein and lysozyme were 60 and 30 mg/g, respectively. This novel nanoparticle provides a simple and efficient method for the enrichment and separation of glycoproteins from biological samples.

Synthesis and Adsorption of Lead Ions by Chitosan–LDHs

Abstract With MgCl2 and AlCl3 as raw materials, nano Mg/Al LDHs were synthesized in situ during the process of chitosan gel formation, and then CS/LDHs composite multilayer hydrogels were prepared and characterized. After calcination at high temperature, they were used to adsorb Pb2+. The concentration of Pb2+ was measured using atomic absorption spectroscopy to investigate the adsorption performance of the composite material. The effects of pH value, initial concentration, and adsorption time on the adsorption efficiency were studied through single factor and orthogonal experiments. The results showed that the optimal process conditions for the adsorption of Pb2+ were pH=5, initial concentration of 2.5g/L, adsorption time of 30 minutes, removal rate of 70.65% at adsorption equilibrium, and adsorption capacity of 1150.32mg/g.

Preparation, Characterization, and Adsorption Performance of H2TiO3 Lithium Ion Sieves with Homogeneous Nanoparticles: Kinetics, Thermodynamics, and Mechanism Analysis

AbstractLi2TiO3 precursor with layered structure is successfully prepared by template‐free method using anatase TiO2 and Li2CO3, followed by the treatment of dilute hydrochloric acid, which leads to obtaining H2TiO3 lithium ion sieve nanoparticles with uniform dispersion and small size. The adsorption performance and mechanism of the H2TiO3 are being studied. The experimental results show that the H2TiO3 lithium ion sieve has a large BET specific surface area (19.10 m2 g−1) and good thermal stability. At the same time, it also has a high adsorption rate and adsorption capacity (55.13 mg g−1) towards Li+ in solution due to its high dispersibility and uniformity of particle size, which can expose more adsorption sites in LiCl solution. The adsorption capacity of the H2TiO3 lithium ion sieve can reach 46.63 mg g−1, which achieves 84.58% of the equilibrium adsorption capacity. The equilibrium adsorption parameters follow the Langmuir model perfectly, demonstrating that Li+ undergoes monolayer adsorption. The results of thermodynamic and kinetic analysis show that the adsorption behavior of H2TiO3 is spontaneous and conforms to the pseudo‐second‐order kinetic model, indicating the adsorption process is controlled by chemosorption. In addition, after five adsorption/desorption cycles, the H2TiO3 lithium ion sieve still shows a high adsorption capacity of 46.15 mg g−1, and the dissolution loss of titanium is only 0.14%, which shows that the cycle stability is excellent. XPS and zeta potential analyses illustrate that the adsorption mechanism of Li+ on the H2TiO3 is an ion exchange reaction between Li+ and H+, combined with the electrostatic attraction of the adsorbent surface. Additionally, the adsorption performance of H2TiO3 lithium ion sieve in West Taijinaier Salt Lake brine was tested, and the adsorbent material proves itself is a perspective candidate for lithium extraction from aqueous lithium resources.

Chemical activation of biochar derived from coffee husk for the adsorption of phytohormones from waste coconut water

Abstract The potential of NaOH-activated biochar derived from waste coffee husks via pyrolysis for the extraction of phytohormones from waste coconut water was investigated. The raw coffee husk biochar (CHB) and coffee husk activated biochar (CHAB) were characterized and compared in terms of morphology, particle size distribution, elemental composition, surface functional groups, bulk density, phytohormone adsorption efficiency and equilibrium adsorption capacity. The phytohormone adsorption efficiency of the CHB and CHAB produced were 62.36% and 91.33%, respectively. Future work includes flask adsorption experiments and using the phytohormone content extracted from the coconut water for tissue culture studies. Collectively, results from this study present an alternative use of coconut and coffee wastes, and ultimately contribute to the waste management processes of the coconut and coffee industries.

Development and assessment of vanadium-based metal–organic frameworks for the effective elimination of hazardous pesticides from aqueous solutions: Mechanism of uptake, adsorption capacities, rate of uptake, and enhancement via the Box-Behnken design

Vanadium metal–organic frameworks (V-MOF) has a great potential to remove contaminants from water that come from agriculture wastewater methyl parathion (MP) pesticides with high effectiveness. Using a variety of methods, such as SEM, FT-IR, XPS), XRD, and BET analysis, the adsorbent was successfully synthesized and characterized. The dimensions of the pores measured at 1.33 nm correspond to the classification of micropores under the IUPAC system. Before the adsorption process, the material had a surface area of 1489.42 m2/g and a pore volume of 0.98 cc/g. After MP adsorption, the surface area, pore size, and pore volume decreased to 1268.42 m2/g, 1.12 nm, and 0.64 cc/g, respectively. Changes in the material’s physical properties indicate that the adsorption process had an effect. 7.2 was the result of controlling the point of zero charge through surface characterization. This information suggests that the surface of the adsorbent has a positive charge at pH below 7.2 and at the pH higher than this value the surface will have a negative charge. It was also looked into how pH affected the adsorption equilibrium. Although fitting to Langmuir isothermally, the kinetics of MP adsorption onto V-MOF are pseudo-second-order fitting. It is very probable that chemisorption was the mode of adsorption because the adsorption energy was 23.62 kJ.mol−1. The enthalpy (ΔHo) values obtained as a result of studying the thermodynamic parameters are positive, demonstrating that, within this temperature range, the pesticide adsorption process was endothermic., measuring 32.79 kJ.mol−1. Entropy (ΔSo) readings that are positive indicate that the system’s randomness increased during the adsorption process, reaching 119 J.mol−1K−1, and with rising temperatures, the negative of ΔGo rise. The effectiveness of the recommended adsorbent was evaluated by filtering wastewater samples in a laboratory environment. It is hypothesized that V-MOF and MP will interact by pore filling, π-π interaction, H-bonding, electrostatic contact, and other possible methods. Considering the specifics of this interaction in great detail is essential to comprehending the nature of adsorption and effectively constructing the adsorbent for use in real-world applications. Water filtering and the treatment of industrial effluents were made simple and effective by the use of V-MOF adsorbent technology. The results indicated that 383.6 mg/g was the maximal adsorption capacity at pH = 6. To evaluate the renewal of the adsorbent, more tests were carried out, and the outcomes showed that the renewal continued even after more than six cycles. The stability of the adsorbent during regeneration was confirmed by using XRD and FT-IR. The Box Behnken design (BBD) was then employed to optimize the adsorption outcomes.

Thermally-switchable adsorbent for selective uranium extraction from wastewater

Uranium extraction from uranium-containing wastewater is a promising solution to the uranium resource shortage, but the extraction process faces significant challenges such as poor selectivity, low elution efficiency, and recovery difficulties. In this study, we developed thermally responsive uranium ion-imprinted magnetic mesoporous microspheres (Fe3O4@mSiO2@FIIP) using polymer F-127 as a thermosensitive switch and sodium phytate as a crosslinking monomer, enabling effective uranium recovery from uranium-containing wastewater. By adjusting the adsorption and elution temperatures, Fe3O4@mSiO2@FIIP achieved higher adsorption selectivity and elution efficiency compared to ion-imprinted magnetic mesoporous microspheres without F-127 (Fe3O4@mSiO2@IIP). Additionally, Fe3O4@mSiO2@FIIP demonstrated superior selectivity for uranium ions over other cations compared to non-imprinted magnetic mesoporous microspheres (Fe3O4@mSiO2@NIP). It exhibited excellent salt resistance, reaching adsorption equilibrium within 60 min with a maximum adsorption capacity of 529.5 mg/g. Life cycle assessment (LCA) and techno-economic assessment (TEA) indicated that Fe3O4@mSiO2@FIIP is more environmentally friendly and economically feasible for treating uranium-containing wastewater. This study provides a new paradigm for synthesizing thermosensitive imprinting materials, holding significant potential for uranium recovery applications.

Comparative adsorption of selected pesticides from aqueous solutions by activated carbon and biochar

ABSTRACT This work aimed to determine activated carbon (AC) and hard wood derived biochar (BC) adsorption capacity for the uptake of four pesticides atrazine, chlorothalanil, α-endosulfan and β-endosulfan from aqueous solution by conducting batch experiments under different experimental conditions. Structural properties of AC and BC were determined through ‘SEM (Scanning Electron Microscope), FTIR (Fourier Transform Infrared Spectrometer) and XRD (X-ray Powder Diffraction Spectroscopy)’. The optimized pH, particle size, contact time, agitation speed and initial pesticides concentration for the maximum adsorption rates were found to be 7, 250 μm, 60 min, 180 rpm and 12 μgL−¹ respectively. Pesticides adsorption were enhanced by increasing pH to 7 while slight decrease were noted when pH increases from 7 to 9. The adsorption equilibrium data were well described by the Langmuir isotherm model having a significant correlation coefficient value from 0.9999 to 1. Adsorption kinetic data were well fitted with the Lagergren's Pseudo-Second-Order kinetic model. The standard Gibb's free energy (ΔG) negative value at every temperature shows the practicability and spontaneity of the adsorption process. While the negative value for enthalpy change (ΔH) indicated the collective impact of exothermic adsorptions process with randomness intensifying due to positive entropy change.

Cationic dye remediation in water treatment with Lizardite–Rice Husk composite: A statistical physics approach

This study presents the development of a novel composite adsorbent, Lizardite-Rice Husk Composite (LRHC), synthesized from lizardite, a mineral derived from chromite ore waste, and rice husk, an agricultural byproduct. The primary objective was to evaluate the efficiency of LRHC in the adsorption of cationic dyes, Malachite Green (MG) and Methylene Blue (MB), from aqueous solutions. Systematic investigations were conducted to assess the influence of adsorbent mass, initial dye concentration, stirring speed, and contact time on adsorption performance. The results revealed that LRHC exhibited optimal adsorption capacities at pH values above 5, with MB and MG adsorption capacities reaching 309.75 mg/g and 51.43 mg/g, respectively. Adsorption equilibrium for MB was achieved within 30 min, indicating rapid dye uptake. Isotherm analysis demonstrated that the Temkin model best described MB adsorption, while the Freundlich model was more suitable for MG, with favorable Langmuir constants. Kinetic studies confirmed that the adsorption followed a second-order model, suggesting chemisorption as the rate-determining step. Intraparticle diffusion and mass transfer were identified as significant contributors to the adsorption process. Thermodynamic studies indicated that MB adsorption was spontaneous (ΔG° = −4.69 kJ/mol for the concentration of 50 mg/L at 298 K) and that MG adsorption was non-spontaneous (ΔG° = 1.52 kJ/mol for the concentration of 50 mg/L at 298 K), with spontaneity increasing at higher initial concentrations. Statistical physics modeling, particularly the monolayer model, provided detailed insights into the adsorption mechanisms and geometry. Furthermore, LRHC demonstrated excellent reusability, maintaining over 80% of its initial adsorption capacity after four regeneration cycles via a heterogeneous Fenton-like reaction. The combination of easy availability, cost-effectiveness, and environmental friendliness makes LRHC a superior adsorbent for the removal of cationic dyes compared to conventional alternatives. This research contributes novel insights into the design and application of composite adsorbents, offering a sustainable solution for water treatment and addressing significant environmental challenges.

Synthesis of highly stable Li4SiO4-based CO2 sorbents using polysilicon by-product SiCl4 as raw material

With the rapid development of the photovoltaic industry, the demand for polysilicon has been continuously increasing. In the production of polysilicon, a large amount of SiCl4 will inevitably be produced as a by-product. Proper treatment of this SiCl4 is crucial for reducing environmental pollution and controlling the production costs of polysilicon. In this study, a by-product of polysilicon production SiCl4 was utilized as a silicon source to synthesize the high-temperature CO2 sorbent Li4SiO4. The effects of SiCl4 content in the precursor solution and CO2 volume concentration on the adsorption performance of the sorbents were thoroughly investigated. The results showed that Li4SiO4-x (x = 0.5, 1.5, and 2.5) exhibited excellent adsorption performance and cyclic stability under 100 vol% CO2 atmosphere, with adsorption capacities of 26.29, 29.66, and 34.04 wt% after 15 cycles, respectively. Additionally, the study found that as the CO2 concentration decreased from 100 vol% to 50 vol% and 15 vol%, the adsorption equilibrium temperature showed a slight shift to the left, and the adsorption capacity also decreased to varying degrees, but the material maintained good cycle stability throughout the process. In summary, the synthesis of Li4SiO4 from SiCl4 has broad application prospects.

Understanding the Adsorption Kinetics of Acetone in Humid Activated Carbons: Perspectives from Adsorption-Breakthrough Experiments and Molecular Simulations.

The presence of water vapor influences the adsorption equilibrium and kinetics of volatile organic compounds (VOCs) in porous materials. By combination of breakthrough experiments and molecular simulations, the competitive adsorption mechanisms of water vapor and acetone on activated carbon with different textures and surface chemical properties at different humidity levels were investigated. Adsorption capacity decreases with increasing relative humidity owing to the formation of preferential adsorption sites between water and the activated carbon surface, while the adsorption rate initially increases and then decreases with increasing relative humidity. Experimental and simulation results revealed that the existence of a small amount of water changed the pore size distributions of activated carbon, thereby promoting the diffusion of acetone molecules. As the relative humidity increased, a portion of the acetone dissolved in water, resulting in a reduction in the adsorption rate. The response of different functional groups to relative humidity was further clarified by molecular simulation. Activated carbons with a high electrostatic interaction with acetone were less affected by humidity and thus exhibit greater potential as adsorbents.

Co-doped NH2-UiO-66 for fast and effective adsorption of oxytetracycline: Kinetics, thermodynamics and mechanism

Novel type of micro mesoporous materials Co-doped NH2-UiO-66 had been successfully prepared. The properties of the material were understood through a series of characterization. When the dosage of Zr:Co is 2:1, the modified material showed specific surface area of 840.02 m2∙g−1, which is larger than the material without Co. Especially, the material was transformed from microporous NH2-UiO-66 to micro-mesoporous Co-doped NH2-UiO-66 through the adjustment of metal Co. The Co-doped nanocomposite was then applied to the adsorption of oxytetracycline. The effects of initial concentration, pH, humic acid and ionic strength on the adsorption were investigated. It was found that 50 mg∙L−1 oxytetracycline can be effectively adsorbed by Co-doped NH2-UiO-66 in pH 7. Further research showed that adsorption was pseudo-second-order kinetics and fitted Freundlich model with the maximum adsorption capacity 223.7 mg∙g−1. In addition, the adsorption equilibrium time was only 2 h, which is shorter than the adsorption time of most adsorbents. The mechanism of pore adsorption, π-π interaction, hydrogen bonds and electrostatic interactions was deeply discussed. In conclusion, Co-doped NH2-UiO-66 was a fast and effective absorbent for the removal of oxytetracycline in aqueous solution.