Maximum Adsorption Research Articles

Synthesis of phosphonic acid and amide functionalized core–shell magnetic composite and its mechanisms for synergistic adsorption of thorium from strongly acidic solution

To develop adsorbents for the preeminent extraction of thorium in strongly acidic solutions is very imperative, due to strong inorganic acids are frequently used in the fuel cycle of thorium. Herein, a robust core–shell magnetic nanocomposite Fe3O4@SiO2/P (MBA-VPA-AM) possessing phosphonic acid and amide was developed via distillation-precipitation copolymerization of N, N'-methylene diacrylamide (MBA), vinylphosphonic acid (VPA) with acrylamide (AM) employing Fe3O4 decorated by SiO2 (Fe3O4@SiO2) as magnetic core. Due to the synergistic effect of phosphonic acid and amide ligand, the sorbent could capture thorium from concentrated HNO3 media efficiently, and the maximum adsorption capacity (qmax) at 4 mol L−1 of HNO3 solution reached up to 232.5 mg g−1, superior to that of all magnetic sorbents reported previously. Furthermore, the sorbent displayed good selectivity towards thorium in the presence of competitive metal ions including La3+, Nd3+, and Ce3+. The excellent thorium sorption behavior in strong hydrogen nitrate solution was merely ascribed to the complexation of thorium with phosphonic acid ligand, and the amide ligand could not complex with thorium, evidenced by XPS, FT-IR and DFT method. However, the presence of amide ligand could enhance the hydrophilicity of the sorbent and the free movement degree of phosphonic acid ligand to a certain extent, both of which could help to promote the thorium sorption on the sorbent in strong HNO3 media. Besides, due to its core–shell structure and superparamagnetism, the sorbent not only exhibited excellent acidic resistance in strong acid medias, but could be magnetically recouped, which could avoid tedious centrifugation or filtration of traditional adsorbents. This work provides a novel strategy to develop magnetic sorbent for the preeminent entrapment of thorium from strong acid solutions.

Antibacterial MXene composite with excellent U/V selectivity for uranium extraction

Uranium, as a radioactive element, is the source of utilizable energy for mankind in the future. Large quantities of uranium resources are contained in seawater, so uranium extraction from seawater is undoubtedly the most feasible method. However, the presence of competitive ions such as vanadium hinders the efficient extraction of uranium, which is currently a challenge that needs to be solved. Here, silane coupling agent (KH550) was grafted onto two-dimensional metal carbide (MXene). Subsequently, salicylaldoxime (SA) was deposited onto MXene particles using self-polymerization of dopamine (DA) to prepare PDA/SA deposited MXene composite grafted with KH550 (PDA/SA/MXene-KH550). The adsorbent exhibited excellent selectivity for uranium ions with a uranium/vanadium selectivity ratio of 4.8. In antibacterial experiments, the PDA/SA/MXene-KH550 composite showed excellent antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), demonstrating the ability to adapt to complex marine microbial contamination. In addition, the maximum experimental uranium adsorption capacity of the composite was 332.3 mg/g, following the pseudo-second-order kinetic model and the Langmuir isotherm model. After five adsorption-desorption cycles, the elution efficiency of PDA/SA/MXene-KH550 for uranium can still reach 74.7 %, which demonstrated that the adsorbent had superior stability and regeneration ability, providing the possibility for actual enrichment of uranium.

Synthesis of carboxymethyl starch co (polyacrylamide/ polyacrylic acid) hydrogel for removing methylene blue dye from aqueous solution

Natural polysaccharides, notably starch, have garnered attention for their accessibility, cost-effectiveness, and biodegradability. Modifying starch to carboxymethyl starch enhances its solubility, swelling capacity, and adsorption efficiency. This research examines the synthesis of an effective hydrogel adsorbent based on carboxymethyl starch for the elimination of methylene blue from aqueous solutions. The hydrogel was synthesized using polyacrylamide and polyacrylic acid as monomers, ammonium persulfate as the initiator, and N,N′-methylenebisacrylamide as the cross-linker. Through FESEM, swelling morphology was evaluated in both distilled water and methylene blue dye. The adsorption data elucidated that the adsorption capacity of the hydrogel significantly depends on the dosage of the adsorbent, pH, and concentration of the MB dye. At a pH of 7 and a dye concentration of 250 mg/L, the hydrogel exhibited an impressive 95 % removal rate for methylene blue. The results indicate that the adsorption process follows pseudo-second-order kinetics and conforms well to the Langmuir adsorption isotherm, indicating a maximum adsorption capacity of 1700 mg/g. According to the pseudo-second-order kinetic model and FTIR analysis, methylene blue chemisorbs to the adsorbent material. Hydrogel absorbents regulate adsorption through both intra-particle diffusion and liquid film diffusion. These results highlight the potential of the new hydrogel absorber for water purification.

Magnetic field-assisted adsorption of phosphate on biochar loading amorphous Zr–Ce (carbonate) oxide composite

For metal-based phosphate adsorbents, the dispersity and utilization of surface metal active sites are crucial factors in their adsorption performance and synthesis cost. In this study, a biochar material modified with amorphous Zr–Ce (carbonate) oxides (BZCCO-13) was synthesized for the phosphate uptake, and the adsorption process was enhanced by magnetic field. The beside-magnetic field was shown to have a better influence than under-magnetic field on adsorption, with maximum adsorption capacities (123.67 mg P/g) 1.14-fold greater than that without magnetic field. The beside-magnetic field could also accelerate the adsorption rate, and the time to reach 90% maximum adsorption capacity decreased by 83%. BZCCO-13 has a wide range of application pHs from 5.0 to 10.0, with great selectivity and reusability. The results of XPS and ELNES showed that the "magnetophoresis" of Ce3+ under the magnetic field was the main reason for the enhanced adsorption performance. In addition, increased surface roughness, pore size and oxygen vacancies, enhanced mass transfer by Lorentz force under a magnetic field, all beneficially influenced the adsorption process. The mechanism of phosphate adsorption by BZCCO-13 could be attributed to electrostatic attraction and CO32–dominated ligand exchange. This study not only provided an effective strategy for designing highly effective phosphate adsorbents, but also provides a new light on the application of rare earth metal-based adsorbent in magnetic field.

Peptides-modified cellulose microspheres for adsorption of ochratoxin A: Performance and mechanism

In this study, peptides with ochratoxin A (OTA) recognition and adsorption capability were designed, among which lysine, histidine, arginine and tyrosine were crucial. Peptide CYFRFYSNLHPK showed the strongest affinity for OTA (Ka = 1.74 × 105 M−1). Theoretical calculations revealed that the differences in the affinity of peptides for OTA were attributed to differences in the type, number and position of amino acids residues. Peptides were conjugated with porous cellulose microspheres to form peptide-modified pretreatment materials (Pep-MPA-RCMs) for adsorption of OTA. The morphology and composition of the prepared Pep-MPA-RCMs were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray diffraction. The effects of pH, adsorption time, initial concentration and temperature on the adsorption process were investigated. The adsorption performance was correlated with the pseudo-second order kinetic and Sips adsorption isotherm model. Thermodynamic studies further proved that the adsorption was exothermic and the prepared Pep-MPA-RCMs showed the maximum adsorption capacity of 9.87 mg/g for OTA at 25℃. A simple adsorption column for OTA was prepared by using Pep-MPA-RCMs as filler material, which still maintained more than 80 % of the removal rate after five consecutive adsorption-elution cycles. The prepared pretreatment material was successfully applied to remove OTA in real samples and was a promising adsorbent for practical applications.

Azadirachta indica leaf extract based green-synthesized ZnO nanoparticles coated on spent tea waste activated carbon for pharmaceuticals and personal care products removal

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants in aqueous systems, posing threat to both human health and environment. In prior research, predominant focus has been on examining various adsorbents for removing PPCPs from single-pollutant systems. However, no study has delved into simultaneous adsorption of PPCPs multi-pollutant mixture. This study evaluates performance of Azadirachta indica leaf extract-based green-synthesized ZnO nanoparticles coated on spent tea waste activated carbon (ZTAC) for removing sulfadiazine (SZN) and acetaminophen (ACN). Adsorption investigations were conducted in single-component (ACN/SZN) and binary-component (ACN + SZN) systems. The synthesized ZTAC was characterized using SEM, XRD, FTIR, EDX, porosimetry and pHpzc analysis. The study examines impact of time (1–60 min), dose (0.2–4 g/L), pH (2–12) and PPCPs concentration (1–100 mg/L) on ACN and SZN removal. Various kinetic and isotherm models were employed to elucidate mechanisms involved in sorption of PPCPs. Furthermore, synergistic and antagonistic aspects of sorption process in multi-component system were investigated. ZTAC, characterized by its crystalline nature and surface area of 980.85 m2/g, exhibited maximum adsorption capacity of 47.39 mg/g for ACN and 34.01 mg/g for SZN under optimal conditions of 15 min, 3 g/L and pH 7. Langmuir isotherm and pseudo-second-order kinetic model best-fitted the experimental data indicating chemisorption mechanism. Removal of ACN and SZN on ZTAC demonstrated synergistic nature, signifying cooperative adsorption. Overall, valorization of ZTAC offers effective and efficient adsorbent for elimination of PPCPs from wastewater.

Utilization of organic-rich materials for the adsorption of copper ions from aqueous environments

This study investigated the suitability of moss peat and compost as adsorbents for removing copper ions from aqueous systems. Kinetic experiments were conducted at pH 4, 20 °C, and an initial copper ion concentration of 20 mM. Under these experimental conditions, moss peat and compost had a maximum adsorption capacity of 45.8 and 41.9 mg/g, respectively. The kinetic data was assessed using several models, and the data fitted well with the pseudo-second-order model for both adsorbents. Moreover, the analysis of the isotherm data showed that the Langmuir model could fit the data, suggesting that copper ions are chemically adsorbed onto moss peat and compost. The pH value of 4.5 was the most effective for the adsorption of copper ions onto moss peat and compost. At this pH value, the maximum adsorption capacities were 60.0 mg/g for moss peat and 56.9 mg/g for compost. The characterization of moss peat and compost before and after the interaction with copper ions indicated that surface precipitation was the dominant mechanism by which copper ions were removed from aqueous systems. Copper precipitation on the surface of moss peat was higher than that on the surface of compost, and it was found to be 7.7 wt% and 3.8 wt%, respectively. Overall, these findings highlight the potential of using moss peat and compost as effective adsorbents for copper ions in highly contaminated water, particularly industrial and mining effluent.

Synthesis and application of dual-functional sorbent SBA-15-Fe3O4-PDA-ODA for removing both water soluble and insoluble pollutants

In this study, inorganic-organic hybrid sorbent SBA-15-Fe3O4-PDA-ODA with functional groups having affinity for both water-soluble and insoluble pollutants was synthesized for treatment of wastewater where Malachite Green (MG) dye and motor oil coexist. In order to enhance the specific interactions between the sorbent and dye via functional groups of polydopamine (PDA), Fe3O4 nanoparticles were encapsulated with SBA-15 and surface functionalization with PDA was accomplished and then the surface of Fe3O4-SBA-15-PDA was modified with octadecylamine (ODA) to remove the oil present in the same environment with dye. While the SBA-15-Fe3O4-PDA-ODA directed to the aqueous phase by magnet provided MG removal thanks to the hydrophilic groups of PDA, it provided motor oil removal thanks to hydrophobicity of ODA when directed to the oil phase. 99.20 % dye removal and 9.24 g/g oil adsorption capacity were achieved from the environment where oil and dye were present together. Besides, the adsorption of MG on Fe3O4-SBA-15-PDA was searched at various pH, dye concentration, adsorbent dosage, and temperature in order to propose optimum experimental conditions for removal of dye and maximum adsorption capacity was determined as 95.83 mg g−1 at optimum conditions (10 mg adsorbent, 10 mg L−1 MG concentration, pH 9). Interaction mechanism between dye and Fe3O4-SBA-15-PDA was explained by studying the adsorption behavior of sorbent derived from the isotherm and kinetic results. The sorbents were characterized by FT-IR, XRD, SEM, N2-adsorption/desorption, water-contact-angle, and VSM measurements. SBA-15-Fe3O4-PDA-ODA sorbent was tested for three successive adsorption cycles for both dye and oil and eventuated insignificant loss in activity when they were recycled. Easy and low-cost fabrication protocol, controllable removal ability of dye and oil will facilitate its versatility in environmental cleanup process for water soluble and insoluble pollutants.

Stepwise extraction of Fe, Si from copper slag and self-assembly synthesis of microspheres for As(V) removal: Resource transformation and environmental governance

Heavy metal pollution control and industrial solid waste management have always been urgent environmental issues. The management of heavy metal pollution through industrial solid waste may be a solution to both problems. In this paper, copper slag (CS) is used as a base material to separate the iron and silicon with a relatively high percentage of content. The Fe-mSiO2/SA (FSA), a microsphere (Φ = 2–3 mm) adsorbent with specific adsorption capacity for As(Ⅴ), was finally synthesized by “Acid leaching & Alkaline extraction & Template synthesis & Gelatinization”. The optimal adsorption conditions were explored using response surface methodology. FSA has a wide range of pH applicability (3–9) and the maximum adsorption capacity is 140.45 mg/g by theoretical calculation. The adsorption process follows pseudo-second-order kinetic model, which indicates that the adsorption process is a surface homogeneous monolayer adsorption controlled by chemisorption mechanism. The synthesis mechanism of FSA was explored by systematic characterization of FSA, and the mechanism of As(Ⅴ) adsorption was elucidated. The −OH and FeOOH formed stable single-tooth or double-tooth complexes with As(Ⅴ) on the surface of FSA. Moreover, the unique spherical structure of FSA facilitates subsequent solid–liquid separation. This study is in line with the concept of economic applicability and “waste for waste”.

Preparation of imprinted phenol gel with ultra-high adsorption capacity based on porous biochar: 5-stage tandem column, response surface method, and mechanism analysis

Wastewater from industries like petroleum refining and pharmaceuticals contains high levels of phenolic compounds. Discharging this untreated wastewater can severely pollute water bodies. To address this issue, a biochar-based composite imprinting phenol gel(MgNBC@MIP) was designed to effectively remove phenolic compounds and control phenol levels in water environments. The adjustment of the aromatic structure and pore architecture of the biochar effectively enhanced its affinity for phenolic compounds. Subsequently, the individual effects of factors such as pH, salt, and humic acid on adsorption were explored. Optimization of the adsorption process was carried out using a four-factor, three-level response surface method, yielding a theoretical formula for the adsorption amount, with a maximum adsorption capacity of 308.311 mg/g. Moreover, the adsorption of phenol and its derivatives by MgNBC@MIP followed the Langmuir isothermal model and the PSO kinetic model. A comprehensive mechanism analysis elaborated in detail on the diffusion and adsorption process of phenol from the aqueous phase to the adsorption site. Correlation FTIR and XPS analysis confirmed that π-π electron donor–acceptor interactions, hydrogen bonding, pore filling, and metal complexation were the primary driving forces for phenol adsorption. Significantly, MgNBC@MIP exhibited good reusability in the adsorption–desorption cycle. The design of a five-stage tandem column adsorption experiment opens up avenues for the industrial application of MgNBC@MIP.

Mesoporous Mg–Al–Ti composite oxide incorporated mixed matrix ultrafiltration membrane with superior multi-heavy metal removal capacity, anti-fouling & anti-microbial property

Mesoporous Mg–Al–Ti ternary composite oxide nano-adsorbents have demonstrated an exceptional performance to remove multiple heavy metals (As, Pb, Cd, Cr). Incorporation of these nanoparticles (NPs) in polysulfone membrane created a multifunctional mixed matrix membrane (MMM) with heavy metal adsorption capacity (both cationic and anionic species), enhanced hydrophilicity, anti-fouling property, and anti-microbial activity. The best heavy metal removal performance was shown by the membrane incorporated with 0.8 wt% NPs. Hydrophilicity improvement was studied through the decrease in water contact angle from 71° to 57° and surface probing using atomic force microscopy (AFM). With a maximum As(III) adsorption capacity of 256.6 mg/g, the membrane had a breakthrough volume of 25L and could provide safe drinking water for 19 h from a real Arsenic (As) contaminated groundwater sample with a flux of 48 l/m2-h. Beyond that, >90 % removal of Cd, Pb & Cr was also observed with maximum adsorption capacity of 652.9 mg/g, 332.5 mg/g, and 89.4 mg/g respectively. 92.5 % flux recovery after filtering a 1000 ppm bovine serum albumin showed the anti-fouling property. Successful inhibition of both gram-positive and gram-negative bacterial growth, and >99.99 % removal of colony forming units (CFU/ml) in the filtration process confirmed the anti-microbial resistance. With its multifunctionality, these membranes hold great potential for practical water treatment applications.

Understanding adsorption mechanisms and metal ion selectivity of superparamagnetic beads with mesoporous CMK-3 carbon and commercial activated carbon

This study investigates, the adsorption capacities of synthesized magnetic hybrid beads containing ordered mesoporous carbon (CMK-3) and commercial activated carbon (commercial AC) for Cd (II), Ni (II), and Hg (II) ions adsorption in single and ternary systems. The order of maximum adsorption capacity was Cd (II) > Ni (II) > Hg (II) in both beads and systems. L13 beads containing CMK-3 exhibit superior adsorption efficiency compared to L3 beads with commercial AC, attributed to the large surface area, enhanced accessibility to adsorption sites, and the presence of O=C bonds, as well as other elements such as F−. Adsorption of all metal ions was described by Freundlich isotherm in L3 beads in both systems, meanwhile in L13 beads, Langmuir and Freundlich models described adsorption differently in both systems and among metal ions, indicating a more complex process. According to the reported maximum adsorption capacity values, L3 beads exhibit a greater affinity for Hg (II) ions, while L13 beads show a higher affinity for Cd (II) and Ni (II) ions. Adsorption in both beads occurred through several mechanisms involving surface complexation, ion-exchange, precipitation, physical and chemical processes. These findings highlight the importance of material design in optimizing adsorption performance for environmental applications, with potential for further enhancement of adsorption capacities and selectivities through future research.

A novel sponge composite of chitosan-sodium tripolyphosphate-melamine for anionic dye Orange II removal

Since the potential carcinogenic, toxic and non-degradable dyes trigger serious environmental contamination by improper treatment, developing novel adsorbents remains a major challenge. A novel high efficiency and biopolymer-based environmental-friendly adsorbent, chitosan‑sodium tripolyphosphate-melamine sponge (CTS-STPP-MS) composite, was prepared for Orange II removing with chitosan as raw material, sodium tripolyphosphate as cross-linking agent. The composite was carefully characterized by SEM, EDS, FT-IR and XPS. The influence of crosslinking conditions, dosage, pH, initial concentration, contacting time and temperature on adsorption were tested through batch adsorption experiments. CTS-STPP-MS adsorption process was exothermic, spontaneous and agreed with Sips isotherm model accompanying the maximum adsorption capacity as 948 mg∙g−1 (pH = 3). Notably, the adsorption performance was outstanding for high concentration solutions, with a removal rate of 97 % in up to 2000 mg∙L−1 OII solution (100 mg sorbent dosage, 50 mL OII solution, pH = 3, 289.15 K). In addition, the adsorption efficiency yet remained 97.85 % after 5 repeated adsorption-desorption cycles. The driving force of adsorption was attributed to electrostatic attraction and hydrogen bonds which was proved by adsorption results coupled with XPS. Owing to the excellent properties of high-effective, environmental-friendly, easy to separate and regenerable, CTS-STPP-MS composite turned out to be a promising adsorbent in contamination treatment.

Removal of Methylene Blue from Aqueous Solutions Using Date Palm By‐Products from Algerian Sahara: Cultivar Variations Effect

AbstractThis study aims to compare the methylene blue (MB) removal capacity from aqueous solutions of seven natural Date Palm (Phoenix dactylifera L.) By‐products (DPBPS). These include: Leaflets (DPLL), Rachis of leaf (DPRL), Fruit Bunch Stalk (DPFBS), Empty Fruit Bunch (DPEFB), Leaf Base (DPLB), fibrillium (DPF) and Spathe Sheath (DPSS), obtained from three different date palm cultivars: Degla, Ghers and Takermost from Ouargla Oasis in the Algerian Sahara, and to investigate the influence of the palm date nature part and cultivar on MB adsorption. Batch adsorption experiments were conducted at different concentrations; 30, 45, 60, 75, 90, and 105 mg/L of MB with 2.5 g of DPBP of each cultivar. The DPBPS of all cultivars exhibits remarkable adsorption efficiencies for MB removal. The highest maximal experimental adsorption capacities were observed for Degla DPLB (4.192 mg/g), Ghers DPF (4.191 mg/g) and Takermost DPF (4.193 mg/g) with(99.81 %), (99.79 %), and (99.82 %) adsorption rates in their cultivar respectively. Conversely, the lowest maximal experimental adsorption capacities were found for Degla DPLL 4.048 mg/g, Ghers DPEFB (4.12 mg/g) and Takermost DPSS (4.089 mg/g) with 96.40 %, 98.09 %, and at 97.67 % adsorption rates in each cultivar respectively. The equilibrium adsorption data were analyzed using Langmuir and Freundlich models. The results indicated a good fit with the Freundlich model. The studied DPBPS represent natural, low‐cost, and locally available adsorbents that effectively remove MB from wastewater.

Bioenergy and value-added chemicals of banana peel waste (BPW): Deeper insights from thermal kinetics, thermodynamics, in-situ volatile products analysis, and bio-chars application for Cd(II) highly-efficient removal

This study presents a comprehensive investigation into the physicochemical properties of banana peel waste (BPW) and its potential for thermochemical conversion into bioenergy and value-added chemicals, supported by the results of kinetics, thermodynamics, in-situ volatile products, and biochar analysis. The physicochemical analysis confirms its potential as a source of renewable fuels and valuable chemicals. Subsequently, based on the TGA outcomes, both kinetic and thermodynamic analysis were conducted. The average activation energy (226–257 kJ mol−1), high heating value (19.56 MJ kg−1), Gibbs free energy (118–149 kJ mol−1), and enthalpy change (222–252 kJ mol−1) all underscore the substantial potential of BPW for bioenergy production and its compatibility for co-pyrolysis with other waste materials. Moreover, Py-GC/MS analysis reveals that the pyrolysis of BPW primarily yields volatile products such as acids, aldehydes, alcohols and ketones, offering a potential source of value-added chemicals. Furthermore, the residual solid biochar exhibits an impressive maximum adsorption capacity of 360.18 mg g−1 for Cd(II) in aqueous environments, thereby further highlighting the exceptional quality of BPW-derived biochar as a superior adsorbent for heavy metals. In summary, this study holds significant importance in promoting the efficient utilization of BPW and mitigating the environmental pollution resulting from improper disposal.

Synthesis of Copper Supported on Natural Rubber-derived Mesoporous Carbon/Silica Composite for Efficient Adsorption of Caffeine

Caffeine (CAF) removal from water resources is important because it is widely distributed and can be toxic to aquatic life. The copper supported on mesoporous carbon/silica composite (Cu/MCS) in this research was developed as a novel adsorbent to remove caffeine from aqueous solutions. The Cu/MCS material was prepared in two steps. The first step was the preparation of a precursor consisting of copper and natural rubber distributed inside a hexagonal mesoporous silica matrix (Cu/NR/HMS). Then, the composite was carbonized at high temperature under inert gas conditions to obtain Cu/MCS material. The amount of Cu loading in the MCS structure was studied. The Cu/MCS composites revealed a high level of copper distribution incorporated into the mesoporous carbon/silica framework as confirmed by Powder X-ray diffraction (XRD) and Scanning Electron Microscope and Energy Dispersive X-ray Spectrometer (SEM-EDS). The Cu/MCS materials possessed a high specific surface area (523–748 m2 g−1), large pore volume (0.80–0.86 cm3 g−1) and mesoporous diameter (3.07-3.30 nm). Fourier Transform Infrared Spectroscopy (FT-IR) and CHN analysis revealed a high amount of carbonaceous species dispersed in the Cu/MCS material. The Cu (0.010)/MCS, with copper loading of 1 mmol/g, revealed good properties for CAF removal when compared to other series of Cu/MCS adsorbents. Moreover, the Cu (0.010)/MCS composite exhibited the maximum adsorption capacity for CAF as 55.8 mg/g.

Synthesis of novel magnetic hydroxyapatite-biomass nanocomposite for arsenic and fluoride adsorption.

A magnetic nanocomposite of hydroxyapatite and biomass (HAp-CM) was synthesized through a combined ultrasonic and hydrothermal method, aiming for efficient adsorption of arsenic (As) and fluoride (F-) from drinking water in natural environments. The characterization of HAp-CM was carried out using TG, FTIR, XRD, SEM, SEM-EDS, and TEM techniques, along with the determination of pHpzc charge. FTIR analysis suggested that coordinating links are the main interactions that allow the formation of the nanocomposite. XRD data indicated that the crystalline structure of the constituent materials remained unaffected during the formation of HAp-CM. SEM-EDS analysis revelated a Ca/P molar ratio of 1.78. Adsorption assays conducted in batches demonstrated that As and F- followed a PSO kinetic model. Furthermore, As adsorption fitting well to the Langmuir model, while F- adsorption could be explained by both Langmuir and Freundlich models. The maximum adsorption capacity of HAp-CM was found to be 5.0mgg-1 for As and 10.2mgg-1 for F-. The influence of sorbent dosage, pH, and the presence of coexisting species on adsorption capacity was explored. The pH significantly affected the nanocomposite's efficiency in removing both pollutants. The presence of various coexisting species had different effects on F- removal efficiency, while As adsorption efficiency was generally enhanced, except in the case of PO43-. The competitive adsorption between F- and As on HAp-CM was also examined. The achieved results demonstrate that HAp-CM has great potential for use in a natural environment, particularly in groundwater remediation as a preliminary treatment for water consumption.

Green synthesis of nZVI-modified biochar significantly enhanced the removal of Cr(VI) from aqueous solution.

Water contamination by hexavalent chromium (Cr(VI)) seriously jeopardizes human health, which is a pressing environmental concern. Biochar-loaded green-synthesized nZVI, as a green and environmentally friendly material, can efficiently reduce Cr(VI) to Cr(III) while removing Cr(VI) from water. Therefore, in this study, an efficient green-modified biochar material (TP-nZVI/BC) was successfully prepared using tea polyphenol (TP) and sludge biochar (BC) using a low-cost and environmentally friendly green synthesis method. The preparation conditions of TP-nZVI/BC were optimized using response surface methodology (RSM), revealing that the dosage of tea polyphenols plays a crucial role in the removal performance (R2 = 1271.09), followed by reaction time and temperature. The quadratic regression model proved accurate. The optimal preparation conditions are as follows: tea polyphenols (TP) dosage at 48 g/L, reaction temperature at 75 ℃, and a reaction time of 3 h. TP-nZVI/BC removed Cr(VI) from water at a rate 7.6 times greater than BC. The pseudo-second-order kinetic model (R2 = 0.987) accurately describes the adsorption process, suggesting that chemical adsorption predominantly controls the removal process. The adsorption of Cr(VI) by TP-nZVI/BC can be well described by the Langmuir model, and the maximum adsorption capacity reached 105.65 mg/g. FTIR and XPS analyses before and after adsorption demonstrate that nZVI plays a crucial role in the reduction process of Cr(VI), and the synergistic effects of surface adsorption, reduction, and co-precipitation enhance Cr(VI) removal. In summary, using green-modified biochar for Cr(VI) removal is a feasible and promising method with significant potential.

Carbon dioxide-activated mesoporous date palm fronds carbon integrated with MnO2/polyaniline for highly efficient capacitive deionization of water.

The continuous population growth and drying up the freshwater reservoirs around the world are increasing the demand for fresh water. Therefore, there is an urgent need to explore newer technologies able to purify water on large scales for human usage. Capacitive deionization is one of the most promising approaches to generate fresh water by the removal of salt ions from brackish water. In this work, we prepared three different capacitive deionization electrodes using carbonized palm tree fronds (PFC). These PFC activation was achieved using CO2 at 900°C. To generate the deionization electrodes, PFC activated carbon was combined with either polyaniline (PANI), MnO2, or both (PFC-PANI, PFC-MnO2, and PFC-MnO2-PANI). The MnO2 and PANI provided additional functionality and enhanced electrical conductivity, which resulted in much higher Na+ and Cl- ions adsorption. The BET surface area of PFC-MnO2-PANI was estimated to be 208.56 m2/g, which is approximately three times that of PCF-PANI and PFC-MnO2 alone. The morphological analysis showed that the PANI and MnO2 nanorods were well dispersed throughout the PFC network. Although PANI and MnO2 is largely embedded inside the PFC network, some remnants are visible on the surface of the electrodes. The cyclic voltammetry (CV) curves showed capacitive behavior of all electrodes in which PFC-MnO2-PANI showed highest specific capacitance of 84 F/g, while the PFC-MnO2 and PFC-PANI showed 42 and 43 F/g, respectively. Owing to its enhanced functionality and CV characteristics, the PFC-MnO2-PANI showed maximum salt adsorption capacity of 10.5mg/g in contrast to 3.72 and 5.64 mg/g for PFC-MnO2 and PFC-PANI, respectively. Moreover, the measured contact angle for PFC-MnO2-PANI was ~51°, which indicates the hydrophilic nature of electrode that improved ions adsorption. PRACTITIONER POINTS: Date tree fronds were converted into mesopores carbon using CO2 as activation agent. Three composites were prepared with PANI, MnO2, and date palm fronds activated carbon (PFC-MnO2, PFC-MnO2-PANI, and PFC-PANI). Surface area, pore profile, surface morphology, electrochemical behavior, desalination performance, and hydrophilicity of all the electrodes were investigated. The PFC-MnO2-PANI showed maximum salt adsorption capacity of 10.5mg/g in contrast to 3.72 and 5.64 mg/g for PFC-MnO2 and PFC-PANI, respectively.

Facile synthesis of lignin/polyethyleneimine foams incorporating zeolitic imidazole framework-8 to efficiently remove tetracycline from aqueous solution

Lignin, as a by-product produced in the biological refining and papermaking processes, is often discarded or burned, resulting in environmental pollution and resource waste. Herein, a novel environmental-friendly ternary hybrid foams adsorbent (SLS/PEI/ZIF-8) was designed for effectively removal TC from aqueous solution. The adsorption properties of the adsorbent were systematically studied. The results show that the adsorption process for TC were fitted well by the pseudo-second-order kinetics model and the Langmuir isotherm model, respectively. The maximum Langmuir monolayer adsorption capacity of SLS/PEI/ZIF-8 for TC was calculated as 1098 mg/g at 30 °C, which was superior to most reported adsorbents. Thermodynamic analysis indicated the adsorption process for TC was spontaneous and endothermic. Moreover, the electrostatic interactions, hydrogen bonding interactions and π–π interactions were proposed as the possible adsorption mechanism. The adsorbent still maintained superior adsorption capacity for TC in ions solution, HA solution and actual water samples, and had good reusability. Therefore, it is a promising adsorbent for the removal of TC from wastewater.