Adsorption Tests Research Articles

Efficient removal of anionic Amaranth azo dye from the aqueous environment using papaya leaf stalks: Studies on batch adsorption, mechanism, and desorption

Papaya leaf stalks (PLS) were utilized in the current research to eliminate Amaranth (AM) dye from an aqueous medium. PLS was characterized through various techniques, including BET/BJH, pHPZC, XRD, FTIR, FESEM, and EDX. The FTIR analysis unveiled that -OH (hydroxyl), -C=O (carbonyl), and -COOH (carboxylic) groups were involved in binding AM to the surface of PLS. Batch mode adsorption tests were conducted, and various operational variables like pH, the mass of PLS, AM dye concentration, contact duration, stirring speed, temperature, and regeneration of the PLS were investigated. The maximal AM removal efficiency of 91.1 ± 2.601% was observed at pH 2.0. The pHPZC of the PLS was determined to be 5.5. The experiment results were analyzed using isotherm models (Freundlich, Temkin and Langmuir) and kinetic models (pseudo-second-order and pseudo-first-order). The pseudo-second-order kinetic and Langmuir isotherm models provided the best fit. The maximal sorption uptake of AM dye on PLS was achieved at 121.3 ± 1.493 mg/g at 298 K. The thermodynamic variables indicated that the sorption process was spontaneous (ΔGo < 0), exothermic (ΔHo > 0), and feasible (ΔSo > 0) at different temperatures. The AM adsorption on PLS was mainly due to electrostatic interactions. Desorption tests were also carried out to investigate the feasibility of regenerating PLS, and 89.2 ± 1.184% of the adsorbed AM was recovered using 0.2 M-NaOH. The reusability results indicated that 76.9 ± 2.204% of the adsorption efficiency could still be maintained even after six cycles. These results demonstrate that PLS is an environmentally friendly and suitable material for removing AM from wastewater.

Enhanced removal of ciprofloxacin antibiotic using agricultural byproduct-derived biochars: From studies on adsorption kinetic, isotherm and thermodynamic to explore mechanistic insights into the removal pathway

BackgroundCiprofloxacin (CIP) antibiotic, classified as an emerging organic contaminant, has caused an adverse impact on the ecological environment due to its persistence. MethodsIn this study, CIP was adsorbed on a novel nanocomposite using lanthanum ferrite spinel nanoparticles (LaFe2O4 NPs) dispersed on litchi shell-derived biochar supporter (BLF) with various loading ratios. The adsorption tests were conducted in batch mode to thoroughly investigate operational parameter effects. In addition, the adsorption kinetics, isotherms, and thermodynamics of CIP onto BLF at various temperatures were systematically studied. The as-synthesized adsorbent was thoroughly characterisized. Finally, CIP adsorption mechanisms onto BLF were revealed. Significant FindingsOur findings showed that the pristine biochar (PBC) was loaded by LaFe2O4, which resulted in more thorough carbonization, enhanced aromaticity, hydrophobicity, porosity, and enriched surface functional groups. The CIP adsorption onto BLF was the highest under optimal operational conditions of solution pH of 5.0, 3.0 g/L biochar dosage, and 50 mg/L initial CIP concentration. The pseudo-second order model best matched the CIP adsorption kinetics with high correlation coefficients of 0.9653-0.9939. The Langmuir model better described the adsorption behaviors of CIP on BLF, with a maximum adsorption capacity of 36.5 mg/g, which was greater than that on PBC by about 1.5 times. CIP adsorption on the BLF exhibited a spontaneous and endothermic nature. The primary mechanisms of CIP adsorption on the BLF were H-bonding and π-π interaction. In particular, La and Fe constituents in BLF functionally enhanced the CIP adsorption via the surface complexation mechanism. These findings illustrated that the BLF was a novel, feasible, and promising adsorbent for the effective removal of CIP antibiotics from water.

The Valorisation of Biochar Produced from Black Liquor Pyrolysis for the Development of CO2 Adsorbents.

The paper manufacturing process produces liquid and gaseous alternative fuels, as well as solid wastes. These can be subsequently treated through chemical processing, oxidation, and thermal activation, resulting in adsorbent materials with CO2 adsorption capacities. The valorisation of black liquor waste resulting from paper manufacturing was achieved through a catalytic pyrolysis process using two catalysts previously prepared in house (Cu-Zn-MCM-41 and Ni-SBA-16). The HCl-treated adsorbent material, resulting from Ni-SBA-16-catalysed pyrolysis, was selected for use in CO2 adsorption tests as it had the highest specific surface area (224.06 m2/g) and pore volume (0.28 cm3/g). The adsorption experimental setup was linked to a gas chromatograph in order to evaluate CO2 adsorption efficiency using a binary gas mixture consisting of 81% CO2 and 19% N2. With a CO2 adsorption capacity of 1.61 mmol/g, a separation efficiency of 99.78%, and a CO2 recovery yield of 90.02%, it can be concluded that the developed adsorbent material resulting from Ni-SBA16-catalysed pyrolysis and HCl treatment represents a viable solution for black liquor pyrolytic solid waste removal and reduction in greenhouse gases.

Microcrystalline cellulose modified chitosan aerogels to enhance Congo Red dye adsorption

Carbohydrate based aerogels were synthesized via a straightforward procedure including freeze-drying of chitosan (Ch) hydrogels of different concentrations cross-linked with glutaraldehyde and incorporating microcrystalline cellulose (MCC) powder to enhance mechanical strength and modify adsorption properties. The increase in Ch content and the incorporation of MCC resulted in samples that exhibited higher densities, lower swelling degrees and accessible porosities while demonstrated improved stabilities. These aerogels were evaluated as adsorbents of the textile dye Congo Red (CR) by isothermal and kinetic studies. Even when relatively simple theoretical models were used to predict these results, in order to eliminate modeling bias, a validation method based on error functions in addition to the more commonly used R2, was applied. Equilibrium adsorption capacities obtained in kinetic studies increased 150 % changing Ch concentration from 4 % to 5 %, and 196 % adding 50 % by weight of MCC. The adsorption tests for initial concentrations of CR below 100 mg/L demonstrated that the aerogels exhibited increased adsorption capacity for higher Ch content or incorporation of MCC. Thermodynamic studies indicated enhanced adsorption at higher temperatures. These environmentally friendly aerogels demonstrated comparable or superior adsorption capacities to other bio-based materials, offering a simple, economical, and effective solution for pollutant removal.

3D Graphene-Like Carbon Structures from Poly(Acrylic Acid): A Novel Synthetic Route.

Emerging contaminants, such as the hormone 17α-ethynylestradiol (EE), in aquatic environments pose a serious risk to both human and environmental health, making efficient removal essential. This study evaluated the effectiveness of three-dimensional porous carbon structures derived from poly(acrylic acid) (PAAc, Carbopol 990) as adsorbents for removing EE from aqueous solutions. Activated carbon materials were prepared using varying ratios of KOH as an activating agent (PAAc : KOH; 1 : 0 AAC, 1 : 1 AC1, 1 : 2 AC2, and 1 : 3 AC3). Adsorption tests were conducted by adding 10 mg of the adsorbent to 40 mL of an EE solution (100 ppm, 20 % acetonitrile in water). Analyses including TGA, XRD, and Raman spectroscopy were performed to evaluate the materials' structural properties and adsorption capacities. Among the materials, AC3 exhibited the highest adsorption capacity for EE (238 mg g-1), followed by AC2 (153 mg g-1) and AC1 (82 mg g-1). The superior efficiency of AC3 can be attributed to its larger surface area and pore volume, enabling greater interaction with EE molecules. These materials demonstrated higher adsorption capacities compared to commercial activated carbons and single-walled carbon nanotubes. This work opens new possibilities for developing efficient adsorbents, contributing to more effective and sustainable solutions for water purification and environmental protection.

Polysulfide-Mediation Properties of Nickel Phosphide Carbon Composite Nanofibers with Controlled Surface Oxidation Layer

The dissolution and shuttle of lithium polysulfides are critical challenges in lithium-sulfur batteries [1]. Metal phosphide-based materials have emerged as promising candidates to address these issues by effectively trapping polysulfides and catalyzing their conversion [2]. Notably, the surface oxidation layer of metal phosphides plays a crucial role in their polysulfide mediation properties, yet its composition and its impact remain largely unexplored [3].In this study, we report the synthesis and characterization of nickel phosphide carbon composite nanofibers with controlled surface oxidation layers by electrospinning with heat treatment, tailored through variations in electrospinning humidity (RH 20%, 25%, and 30%). We evaluated the performance of the prepared materials as sulfur hosts in lithium-sulfur batteries and compared their polysulfide mediation properties.Polysulfide adsorption test was performed by placing 10 mg of prepared fibers into 3 mL of 0.002 M Li2S6 solution in 1,3- dioxolane (DOL)/1,2 dimethoxyethane (DME) (v/v, 1:1). After 30 minutes of adsorption test, the resulting solutions were subjected to UV-Vis analysis. The conversion kinetics of polysulfides on the prepared fibers was evaluated by cyclic voltammetry (CV) of symmetric cells with 1 M Li2S6 solution at scan rate of 3 mV s-1 and cell voltage range of -1.5-1.5 V, using fibers both as working and counter electrodes.According to results, although strong adsorption ability is demonstrated by all three samples, an obvious difference in the decolorization of the solutions depending on the electrospinning humidity is observed (Figure 1a). This difference can be further clarified from the UV-Vis spectra of decolorized polysulfide solutions in Figure 1b, where the highest adsorption ability corresponds to fibers prepared at RH 25%. On the other hand, the polysulfide mediating properties of the prepared fibers follow different trends, as illustrated in Figure 1c. Distinct oxidation-reduction peaks are observed in the case of RH 30%, indicating strong catalytic effect on the polysulfides conversion to final products.The effect of such contradiction on the electrochemical performance of the fibers as sulfur host will be further studied and presented at the conference. Acknowledgments This research was funded by the research targeted program #BR21882402 “Development of new material technologies and energy storage systems for a green economy” and the projects AP13068219 “Development of multifunctional free-standing carbon composite nanofiber mats”, AP19675260 “Development of nanofibrous electrode materials for next-generation lithium-ion batteries” from the Ministry of Science and Higher Education of the Republic of Kazakhstan.

Interweaving two dimensional mesoporous covalent organic frameworks for efficient removal of mercury from aqueous solution

The current study defines the ultrasound-assisted solvothermal synthesis of covalent organic frameworks (COFs) using a combination of 4,4′-diaminobiphenyl and trialdehyde (BDTA-COF). The X-ray diffraction (XRD) studies confirm the formation of COF, which aligns better with AA stacking than AB stacking. The morphology of the formed COFs is a flower-like structure. The Fourier transform infrared spectroscopic (FTIR) results show that imine linkages are forming and that the aldehayde and amine peaks are not present. The formed BDTA-COF was found to be mesoporous and exhibit 2.4 nm pore size with 472 m2g−1 surface area. BDTA-COF has been evaluated for the effective removal of Hg+ from an aqueous solution through adsorption. Maximum adsorption efficiency (99 %) was achieved by optimizing the parameters like selectivity of metal, concentration, pH, amount of adsorbent. The nitrogen atoms from the imine linkages and the oxygen atoms in BDTA-COF are the primary active sites for effective adsorption of Hg⁺. The adsorption kinetics control the chemisorption of Hg+ with the BDTA-COF's imine group since the results fit well with the pseudo-second-order model. Among the various isotherm models, the BDTA-COF/Hg+ system followed the Langmuir model and insists on the monolayer adsorption phenomena. After adsorption, the XRD shows a slight change in peak positions, and the SEM image indicates the deposition of micrometer-sized particles onto the BDTA-COF. After adsorption, FTIR and X-ray photoelectron spectroscopic (XPS) tests show the interaction of functional groups of BDTA-COF and Hg+. High surface area, covalency, porosity, ordered confinement, imine linkages and stability of COFs could be the reasons for good adsorption efficiency and need additional tuning for practical applications for adsorption removal of pollutants from water.

Dynamics of HPAM flow and injectivity in sandstone porous media

Polymer flooding is a prominent chemical enhanced oil recovery (CEOR) method that involves the injection of polymer solution into the oil reservoirs to improve the sweep efficiency and maximize the ultimate oil recovery. Selecting an appropriate polymer type, molecular weight, and concentration is crucial for success of any polymer flooding project. This paper studies the flow behavior of HPAM-based EOR polymers with different molecular weights through porous media. Dynamic adsorption and injectivity tests were performed through 5 Darcies sandpacks using polymer solutions prepared with low (LM; 8–10 MDa) and high (HM; 20–25 MDa) molecular weight polymers. Polymer solutions with different target viscosity values of 7, 15 and 30 cP were flooded through sandpacks at the reservoir temperature of 80 ºC and pore pressure of 1000 psi. The results showed that HM solutions with different target viscosity have higher polymer retention through sandpacks compared to LM solutions. Furthermore, results of residual resistance factor (RRF) measurements were in line with dynamic adsorption tests results. That is, permeability reduction due to irreversible polymer retention was higher when HM polymer solutions were injected. Furthermore, the results showed that although the resistance factor (RF) and in-situ viscosity of HM and LM polymers are in the same range, however, shear thickening regime becomes pronounced in the case of HM polymer with higher target viscosity. Polymer relaxation time measurements, and consequently, Deborah number calculations were performed to describe the shear thickening behavior by polymers viscoelastic characteristics. Results demonstrate that occurrence of shear thickening regime is controlled by Deborah number which is a function of polymer molecular weight, polymer concentration and injection rate. These results shed light on the importance of the selection of optimal polymer molecular weight and concentration during the design of polymer flooding projects.

Action of Low-Density Polyethylene Microspheres in the Transport of Metformin Hydrochloride in Aqueous Medium Through Adsorption and Desorption

The present study addresses the issue of transporting pharmaceuticals via microplastics in aquatic environments. For this purpose, the adsorption and desorption of metformin hydrochloride (MET), a hydrophilic compound, on polyethylene microspheres (PMEs) were studied via batch adsorption and desorption capacity and kinetics tests. The adsorption test results indicated minimal influence of pH values above 5, alongside a decrease in adsorption capacity with an increasing mass of PMEs. The Freundlich model best represented the adsorption capacity data; however, values of n &lt; 1 (0.6) and low K suggest a decrease in the sorption affinity of MET with increasing initial MET concentration and a low affinity of MET for PM beads. The rate and equilibrium of adsorption were fast, and the results adequately fit the pseudo-first- and pseudo-second-order models, suggesting that physical and chemical mechanisms contributed to the adsorption of MET onto the PEMs under the conditions of this study. The desorption equilibrium result was 1.3 mg g−1 ± 0.04 mg g−1, without significant change, regardless of the initial amount of adsorbed MET. However, the desorption percentage varied between 26.14% and 7.01% as a function of the amount. of MET adsorbed onto the PMEs. These results suggest that PMEs could be potential vectors of MET transport in aquatic environments.

Chemical and thermal modification of geopolymer for efficient dye removal.

In the pursuit of advancing sustainable wastewater treatment solutions in the industry, this study investigates the effect of chemical and thermal modifications on adsorbent geopolymer (GP) structure. Optimal conditions of sulfuric acid treatment and calcination temperature were determined to enhance the adsorption of the direct red dye 28 (DR28). Functional groups (FTIR), mineralogical composition (DRX), morphology (SEM-EDS), and physical properties (BET/BJH) were employed to study the effect of attack with H2SO4 and calcination on GP characteristics. The modified GP exhibited a high specific area (190 m2g-1). Adsorption tests indicated that the Elovich model satisfactorily describes the kinetics, while the Sips model represents the isotherms. The maximum adsorption capacity achieved was 107.5mgg-1. Remarkably, the adsorption capacity was doubled with GP regeneration, allowing reuse for three cycles. Furthermore, the selectivity profile uncovers a pronounced affinity hierarchy for dyes, with direct dyes manifesting a superior attraction, followed by acid, reactive, and disperse dye categories. Analyzing the efficiency of GPAT and comparing it with other GPs, it is evident that GPAT is an efficient and versatile adsorbent, featuring a simplified production process and requiring milder temperatures than those needed for activated carbon. Additionally, the cost-benefit analysis highlights geopolymers as a more economical and efficient alternative compared to conventional adsorbents.

Synthesis and doping of alkali metals on MOF-74 for CO2 and CH4 pure and binary mixtures adsorption

The emergence of the industrial revolution, marked by a global supply-demand network mostly dependent on fossil fuels, has resulted in the generation of carbon emissions. Metal-organic frameworks (MOFs) have materialized as a innovative category of adsorbents extensively studied by researchers on CO2 adsorption over recent years because of their significant adsorption capability. Amongst the different types of MOFs, Mg-MOF-74 is known for its open metal sides and its applicability of CO2 adsorption on flue gas. This work modifies Mg-MOF-74 by doping alkali metal cations (Na, Li, and K) to improve the efficacy of CO2 adsorption. The crystal structures of pure Mg-MOF-74 and Mg-MOF-74 doped with Na, Li, and K were compared by characterization using field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), and Brunauer-Emmet Teller (BET) surface area. A CO2 adsorption test determined the CO2 adsorption capacity of the modified Mg-MOF-74 at 70 °C temperature and up to 50 bar pressure. It was found that the BET specific surface area and the pore sizes of Mg-MOF-74 increased gradually by doping with Na, Li, and K by 7.07%, 11.75 %, and 14.91%. The CO2 and CH4 adsorption breakthrough experiment shows that the CO2 adsorption capacity has been increased from 8.9 wt% to 11.68 wt% under dynamic conditions.

Research on effective mercury removal from flue gas over Cl/Br/I/O modified adsorbents at ultra-low temperature

Our proposed COAP (Cold Oxidation Adsorption Process) technology has shown effective adsorption of SO2 and NOx in flue gas (emission <1 ppmv), making it a potential future flue gas treatment technology. The core component of this technology, the adsorption tower, aims to adsorb SO2 and NOx at low temperatures (-40–0°C). Interestingly, we found it has synergetic effects on mercury removal and its mechanism still remains uncertain in the existing literature. Therefore, this research investigated the behavior of mercury oxidation by activated coke adsorbents modified with typical active components (Cl/Br/I/O) at ultra-low temperatures. The effects of common modification methods on the adsorption of activated coke at low temperatures were investigated using a low-temperature adsorption test benches. The oxidation mechanism of mercury on the adsorbent surface at low temperatures was revealed by BET and XPS characterization, showing that O* and C-X (where X = Cl, Br, I) play key roles in mercury adsorption at low temperatures. In addition, the promotion effect of SO2 and NO on mercury removal in O2 environment is more obvious at low temperature than at high temperature. This may be due to the oxidation reaction as an exothermic reaction, low temperature is conducive to the oxidation reaction. In order to clarify the distribution characteristics of mercury at low temperatures, the used activated cokewas used for Hg-TPD analysis. The experimental results indicate that low temperature does not alter the reaction pathway and reaction products. Overall, halogen and oxygen modified activated coke adsorbent showed superior Hg removal performance at low temperatures and this study is expected to provide deep understanding of mercury reaction mechanism at low temperature.

Adsorptive processes applied to the defluorination of groundwater for human consumption

Contamination of groundwater by fluoride ions can occur through both natural and anthropogenic activities, such as the discharge of industrial waste containing this compound. Thus, effective fluoride removal from groundwater is essential to ensure safe drinking water. This study evaluated the performance of adsorption techniques for defluoridating groundwater in Rio Grande do Sul, Brazil. Preliminary tests were conducted using synthetic solutions with a fluoride concentration of 5 mg.L−1, applying several adsorbents. Additionally, an ultrasonic process was used to synthesize an adsorbent from activated alumina pre-treated with carbon (AACP) and modified with ZnCl₂ (AA-ZnCl₂). The AACP and AA-ZnCl2 were characterized through BET, EDS, scanning electron microscopy, X-ray diffraction (XRD), and FT-IR analysis. A Central Composite Design and response surface methodology were applied to optimize adsorption efficiency, focusing these factors: pH and adsorbent dosage. Kinetic and isotherm adsorption tests were conducted for both AACP and AA-ZnCl₂. The results showed that AACP achieved fluoride removal efficiencies of 65.4 % in synthetic solutions and 38.6 % in groundwater. The AA-ZnCl₂ demonstrated superior performance, removing over 98 % of fluoride in synthetic solutions and 55.4 % in groundwater, across a pH range of 4 to 10, with an optimal solid dosage of 3 g.L−1. For an initial fluoride concentration of 5 mg.L−1, a removal efficiency of 97.4 % was achieved within 5 min of contact time. The kinetic adsorption data were best described by the pseudo-second-order model, while the Freundlich isotherm model provided the best fit for the adsorption isotherm data. The findings in this work indicate hat ZnCl₂-modified activated alumina, synthesized with ultrasonic assistance, is highly effective for defluoridating groundwater for safe human consumption being an alternative method to be implemented in an industrial scale.

Enhanced VOCs adsorption over ZSM-5 nanosheets with different thicknesses along the b-axis

A systematic study was conducted on the effect of the b-axis thickness on the adsorption/desorption properties of representative VOCs (toluene and dichloromethane) by varying the diffusion resistance over ZSM-5 nanosheets. ZSM-5 nanosheets with about 30 nm thickness along the b-axis (Z5-3) presented a 1.3-fold higher adsorption capacity (83.9 mg/g) and 27 % enhancement in breakthrough times for toluene (38 min) compared with conventional ZSM-5 (Z5-4). Dichloromethane adsorption capacity on Z5-3 (micropore volume of 0.12 cm3/g) was approximately 53 % higher than that on Z5-4 (micropore volume of 0.08 cm3/g) and only weekly correlated to the b-axis thickness due to its small molecular size. The adsorption isotherms and molecular dynamic simulations indicated that a shorter b-axis thickness enhanced the diffusion of toluene (3.9 × 10-5 cm2/s) and dichloromethane (7.2 × 10-5 cm2/s), as well as the toluene adsorption capacities over ZSM-5 samples. The toluene and dichloromethane physisorption mechanism was verified by adsorption kinetics. Additionally, the toluene and dichloromethane adsorption capacities of all samples decreased by about 33 % and 21 % at a relative humidity (RH) of 50 % at 298 K, respectively. This indicated that the structure of ZSM-5 samples did not significantly affect their hydrophobicity. Moreover, according to the competitive adsorption test results, toluene and dichloromethane underwent successive co-adsorption, competitive adsorption, and equilibrium adsorption. These findings are useful for designing high-performance and cost-effective zeolite adsorbents to efficiently remove volatile organic compounds from industrial sources.

Assessment of the adsorption capacity of biochar samples obtained from agricultural biomasses

The study consists of adsorption tests on two samples of biochar, obtained from rice husk and coconut fiber biochar biomass, as well as a sample of charcarbon, both prepared under different conditions: macerated and non-macerated; impregnation with and without HCl and H3PO4; and washing or not with deionized water after impregnation. The test was performed in duplicate, for 30 min, with masses of 0.5 g; 0.3 g; 0.1 g; and 0.05 g, and an initial methylene blue concentration of 0.01 g∙L-1. The study was carried out with the objective of identifying, in the analyzed samples, the material with the greatest adsorption capacity of methylene blue dye, comparing the data with commercial activated carbon. The results identified removal above 70 % in both types of biochars, suggesting the feasibility of application as an adsorbent material to remove organic contaminants. The sample that most closely resembled the removal percentage of commercial activated carbon (98.84 %) was that of biochar obtained from coconut fibers, with 91.71 %. Thus, the research showed promise in studying the application and valorization of biochars, produced from agro-industrial waste, in adsorption processes.

Defect-riched prussian blue analogues with superior adsorption-catalysis toward lithium polysulfides for high performance lithium-sulfur batteries

Lithium‑sulfur batteries (LiS) garner significant interest within the energy storage industry, because of their exceptional theoretical energy density coupled with employment of environmental materials. Nevertheless, the broader implementation of LiS batteries faces challenges, primarily due to the lithium polysulfide (LiPSs) shuttle effect and the sluggish conversion kinetics associated with LiPSs. In this work, we introduce a reduction-induced dissolution process to fabricate a mesoporous CoFePB rich in crystal defects via a facile solvothermal method. The experimental results indicate that the abundance of crystal defects originate from the phase transition from Co3[FeIII(CN)6]2 to Co2[FeII(CN)6]. The subsequent adsorption tests and electrochemical evaluations have shown that the defect-rich CoFePB possesses enhanced LiPSs absorption capacity and improved cycling performance in contrast to the pristine CoFePB, which is primarily ascribed to proliferation of active sites emerging as a result of the crystal defects. Consequently, the D-CoFePB-S cathode demonstrates remarkable rate performance with 583 mAh g−1 at a substantial 5C current rate, superior long-term stability with capacity retention of 64.3 % over 2000 cycles at current rate of 2C and outstanding areal capacity of 4.9 mAh cm−2 at 0.1C, even under a substantial sulfur loading of 5.0 mg cm−2.

Efficient removal of chromium from electroplating sludge by a novel combined process of alkaline oxidizing roasting, water leaching and on-line adsorption

Chromium-bearing electroplating sludge (ES) is a typical hazardous waste that poses significant environmental risks due to the toxic and carcinogenic nature of chromium. In this study, Cr extraction is performed by roasting with Na2CO3 and water leaching from ES, and finally recovered by an on-line adsorption process by using an eco-friendly material. Under Na2CO3 roasting and water leaching, 82.1 % of Cr was leached out, with conditions of 800 ℃, Na2CO3 dosage amount at 30 %, and a residence time of 2 h for the roasting step, and solid-liquid ratio of 1:2 for the water leaching step. The results of the column adsorption tests indicated that FH/ SCB exhibited superior adsorption performances toward Cr (VI) with a maximum adsorption capacity of 20.5 mg/g, and its adsorption isotherm was matched with the Laugmuir model. About 97.4 % of Cr was recycled from the ES under the dynamic on-line adsorption process, furthermore, the total content of Cr in the final effluent was lower than wastewater discharge standards of 0.5 mg/L. In conclusion, this combined method presents an alternative approach for the eliminating, detoxifying, and reusing of chromium-bearing ES.

Preparation and performance study of heparinized multi‐walled carbon nanotube/cellulose acetate hemodialysis membrane

AbstractCurrently, the incidence of kidney failure is increasing worldwide. Hemodialysis is the main method for the treatment of kidney diseases, and the continuous development of new hemodialysis membranes is the key to improve the treatment effect and the quality of life of patients. In this study, heparinized multi‐walled carbon nanotube/cellulose acetate (Hep/MWCNTs@CA) membranes were prepared by non‐solvent induced phase separation (NIPS). The morphology and pore structure of Hep/MWCNTs@CA membranes were characterized by scanning electron microscopy (SEM). The elongation at break and tensile strength of the membranes were characterized by a mechanical property universal tester. The results showed that mechanical properties of 0.1 wt% MWCNTs enhanced the membrane is best. The water contact angle test confirmed that MWCNTs can improve the membrane hydrophilicity, and combined with the adsorption test results for proteins, it was found that the hydrophilicity can reduce the adsorption of proteins to the composite membrane and improve the blood compatibility of the material. The dialysis performance of urea and lysozyme was tested by a self‐made simulated hemodialysis device, and the clearance rates of urea and lysozyme were 84% and 47.2%, respectively, which showed that the interfacial gap between MWCNTs and CA matrix can make the composite membrane retain a high retention rate of macromolecular proteins (92.3%) and further improved the clearance rate of small and medium molecular toxins. In addition, the good blood compatibility and biocompatible properties of the materials were confirmed by hemolysis, recalcification and cytotoxicity tests on Hep/MWCNTs@CA membranes. In conclusion, the prepared Hep/MWCNTs@CA holds great potential for application in the field of hemodialysis.

Efficient Removal of Cu(II) and Ni(II) Ions from Aqueous Solutions Using Reduced Graphene Oxide/Bentonite Clay/ZnO Nanocomposites: Kinetics, Mechanisms, and Adsorption Performance

&lt;p style="text-align:justify;text-indent:36.0pt;"&gt;&lt;span style="font-family:&amp;quot;Arial&amp;quot;,&amp;quot;sans-serif&amp;quot;;font-size:11pt;line-height:150%;"&gt;To assess the efficacy of removing heavy metals such as Cu (II) and Ni (II) ions from aqueous solution, the adsorption behaviour of a nanocomposite powder comprising of reduced Graphene Oxide (rGO), bentonite clay, and ZnO was investigated. Various analytical techniques including Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, Energy-Dispersive X-ray spectroscopy, X-Ray diffraction analysis, and N&lt;sub&gt;2&lt;/sub&gt; adsorption/desorption analysis were utilized to analyse the synthesized composites. Through the batch equilibrium approach, parameters influencing adsorption behaviours, including initial metal ion concentration, pH, adsorbent dosage, and contact time, were comprehensively examined. Adsorption data were shown to have good fit to the Langmuir isotherm model and pseudo-first-order model, with high R&lt;sup&gt;2&lt;/sup&gt;, low root mean square error (RMSE), low chi square (Χ&lt;sup&gt;2&lt;/sup&gt;), and low standard deviation (SD) values when using the linear regression approach. For the raw sample (rGO/ bentonite clay) containing copper and nickel, equilibrium was achieved in 80 minutes, while for samples with 1% (rGO/ bentonite clay/1% ZnO), 3% (rGO/ bentonite clay/3% ZnO), and 5% (rGO/ bentonite clay/5% ZnO), equilibrium was attained within 70 minutes. &lt;/span&gt;&lt;span style="background-color:white;font-family:&amp;quot;Arial&amp;quot;,&amp;quot;sans-serif&amp;quot;;font-size:11pt;line-height:150%;"&gt;Within the pH range of 2 to 12, the adsorption kinetics of copper and nickel exhibited a notable pH-dependent relationship, highlighting the pronounced influence of pH conditions on the adsorption process&lt;/span&gt;&lt;span style="background-color:white;color:#374151;font-family:&amp;quot;Segoe UI&amp;quot;,&amp;quot;sans-serif&amp;quot;;font-size:11pt;line-height:150%;"&gt;. &lt;/span&gt;&lt;span style="background-color:white;font-family:&amp;quot;Arial&amp;quot;,&amp;quot;sans-serif&amp;quot;;font-size:11pt;line-height:150%;"&gt;Copper consistently demonstrated superior removal efficiency compared to nickel in all conducted adsorption tests, attributed to its heightened propensity for bond formation with adsorbent surfaces.&lt;/span&gt;&lt;span style="font-family:&amp;quot;Arial&amp;quot;,&amp;quot;sans-serif&amp;quot;;font-size:11pt;line-height:150%;"&gt; The primary pathways for copper and nickel adsorption on the composites involved intermolecular interactions, cation exchange, physisorption and electrostatic interactions. The Langmuir model revealed maximum Cu (II) adsorption capacities of 312.5 mg/g, 217.39 mg/g, 161.95 mg/g, and 101.96 mg/g for raw sample, 1%, 3%, and 5% samples, respectively. Nickel (II) adsorption capacity were measured at 252.41 mg/g, 185 mg/g, 125.03 mg/g, and 96.60 mg/g for the raw sample, 1%, 3%, and 5% samples, respectively.&lt;/span&gt;&lt;/p&gt;

Experimental exploring of Ti3C2Tx MXene for efficient and deep removal of magnesium in water sample

In this work, the mechanism and behaviour of magnesium adsorption with Ti3C2Tx adsorbent is investigated. Ti3C2Tx was synthesized by selective exfoliation of Al layer from Ti3AlC2 using acidic solutions of HF 40% and 12 M LiF/ 9 M HCl. The effect of the synthesis method on the structure, the interlayer distance, the type and abundance of the functional groups, the bonds formed, the surface area and the volume of the formed cavities were evaluated by X-ray diffraction, scanning electron microscopy, Energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller and fourier transform infrared analyses. The preliminary discontinuous tests of magnesium adsorption with Ti3C2Fx and Ti3C2(OH)x in 100 ppm concentration, pH ~ 7.00, ambient temperature and time of 3 h show 182.5 and 99 mg.g-1 the adsorption intensity, respectively. The difference in adsorption intensity with Ti3C2Fx is the result of the extensive tendency of Mg2+ to conduct electrochemical reactions with F- twice as much as OH- functional groups. By designing the RSM experiment, analytical, qualitative, optimization and modelling of the magnesium adsorption process with Ti3C2Fx adsorbent was carried out with the input variables of magnesium concentration, pH, ambient temperature and time. Isothermal modelling shows the agreement of the experimental results with the Langmuir model and endothermic thermodynamic modelling shows the spontaneity of the adsorption reaction. MXene adsorption–desorption with 0.1 M HCl was done in up to 4 steps. The adsorption results show that Ti3C2Fx can show up to 15% initial adsorption intensity by maintaining stability in up to 4 adsorption–desorption steps.