Recovery and separation of Mo(VI) and Re(VII) from Mo-Re bearing solution by gallic acid-modified cellulose microspheres

Efficient adsorption of Sb(III/V) by zirconium-functionalized cellulose microspheres and their application in actual underground water of mine cavern

At present, with the mining of antimony, highly toxic antimony has seriously threatened the safety of water sources and jeopardized human health. It remains a challenge to create adsorbents that are easy to separate, efficient and have high adsorption capacity. In this study, the zirconium-functionalized MCC microspheres (MCC-g-GMA-IDA-ZrOCl2) have been successfully synthesized using radiation grafting technique and applied for Sb(III/V) capture. Batch systematic adsorption experiments indicate that the experimental data for Sb(III/V) conform to the pseudo-second-order kinetic model with Langmuir maximum adsorption capacities of 56.25 mg/g (Sb(III)) and 240.96 mg/g (Sb(V)), respectively. Combining XPS and FTIR characterization with experimental data, it is reasonable to assume that MCC-g-GMA-IDA-ZrOCl2 removes antimony from aqueous solutions by ligand exchange, electrostatic attraction and surface complexation mechanisms. Column experiments demonstrate that MCC-g-GMA-IDA-ZrOCl2 selectively traps Sb(III/V) in underground water of mine cavern. Through the above adsorption performance tests, MCC-g-GMA-IDA-ZrOCl2 is expected to treat Sb(III/V) in antimony contaminated groundwater on a large scale in industrial water.

Interfacial adsorption behavior of amine-functionalized MCM-41 for Mo(VI) capture from aqueous solution

Given the environmental and ecological risks posed by wastewater bearing molybdenum, the characteristics and microscopic interactions of existing silica-based adsorbents have not been thoroughly investigated, highlighting the need to enhance the porosity and chemical interactions of these materials. Considering the effectiveness of amino groups in binding metal oxyanions, this study investigates the adsorption performance and mechanism of amino-functionalized MCM-41 for Mo(VI), with the goal of efficiently remediating Mo-contaminated wastewater. MCM-41 modified by amino group retains its original structure and mesoporous characteristics while featuring a positively charged surface and chemically bonded amino groups. When employed to treat Mo(VI)-containing solutions, adsorption equilibrium is attained within 20 min, adhering to pseudo-second-order kinetics, characterized by a high R2 value of 0.9999, indicating a predominantly chemisorptive method. Thermodynamic evaluation offers uniform single-layer adsorption of specific ions onto the adsorbent interface. It demonstrates the nature of the adsorption method being spontaneous and fits the Langmuir model. A maximum of 242.33 mg/g of adsorption capacity was achieved. Spectroscopic characterization confirms that charge attraction, hydrogen bonding, and coordination are the primary driving forces behind the method of adsorption. Density Functional Theory (DFT) results further support the advantageous role of two-tooth chelation between amino group and silanol groups in the Mo(VI) adsorption mechanism. This study provides information on adsorbent design and the control of Mo(VI)-containing aqueous solutions by confirming the substantial promise of amino modified mesoporous silica with suitable pore configurations for treating Mo(VI)-containing solutions.

Green crosslinking with oxidized sodium alginate for enhanced Mo(VI) adsorption in alginate-based membranes

The use of green and nontoxic crosslinking agents in material synthesis is both important and challenging. In this study, oxidized sodium alginate (OSA) was synthesized via sodium periodate oxidation and used for the preparation of sodium alginate/polyethyleneimine membranes. FTIR confirmed the presence of aldehyde groups after the oxidation of sodium alginate. In addition, the appearance of the Schiff base structure of the OSA membrane indicated that crosslinking was successful. SEM revealed the roughness and porosity of the surfaces of OSA membranes, which were favourable for the adsorption of Mo(VI). XPS indicated that adsorption was potentially related to the coordination reactions of amino groups on PEI and to electrostatic attraction. Permeation characterization revealed that the membrane had excellent mechanical strength and durability. The maximum adsorption amount calculated via the Sips equation was 452.112 mg g-1 at 50 °C. The adsorption process followed pseudo-second-order kinetics and was spontaneous, as confirmed by thermodynamic analysis. Competing ions, simulated of industrial wastewater and cyclic desorption experiments confirmed the good practical application of this material. Overall, the OSA membrane showed good performance in removing and recovering Mo(VI) from aqueous solutions, and OSA was determined to be a green crosslinker comparable to glutaraldehyde (GA).

Application Progress of Electron Beam Radiation in Adsorption Functional Materials Preparation

To solve the problems of water and air pollution, adsorption functional materials (ASFMs) have been extensively investigated and applied. Among the preparation methods of ASFM, electron beam radiation (EBR) has attracted much attention for its high efficiency, environmental friendliness, and wide applicability. Based on the introduction of the application of EBR technology, the EBR preparation of ASFM is summarized by grafting and cross-linking. Secondly, the application of corresponding ASFM for the adsorption of metal ions, inorganic anions, dyes, drugs and chemical raw materials, and carbon dioxide is summarized systematically. Then, the adsorption mechanisms of ASFM are illustrated, according to the different pollutants. Finally, the progress, issues, and prospects of EBR technology for ASFM preparation are discussed.

Stable and antibacterial tannic acid-based covalent polymeric hydrogel for highly selective Pb2+ recovery from lead-acid battery industrial wastewater

The resource of trace lead (Pb2+) from wastewater bearing intricate components is imperative for sustainable progression of the lead-acid battery industry. Herein, we fabricated a tannic acid-based covalent polymeric hydrogel (TA@PMAM) with antimicrobial properties and stability via facile Michael addition reaction. The incorporation of tannic acid (TA) through robust covalent bond leads to a stable porous 3D covalent polymer network with almost no loss of mechanical properties even after 20 compression cycles. Batch adsorption experiments of TA@PMAM revealed an extraordinary adsorption capacity of Pb2+(Qe =196.6 mg/g), achieving 87.2 % of Pb2+ adsorption within the first 5 min owing to porous structure, numerous adsorption sites and good hydrophilicity. Moreover, TA@PMAM demonstrated a strong affinity for Pb2+ in the presence of the interfere metal ions (Cu2+, Co2+, Mn2+etc.) due to the carbonyl and phenolic hydroxyl that can specifically pair with Pb2+. Stable adsorption properties of TA@PMAM were confirmed in fixed bed column adsorption experiment using lead-acid batteries wastewater, retaining 79.56 % of initial adsorption capacity even after 10 times' reuse. Besides, TA@PMAM possesses a broad spectrum of antimicrobial properties. This study sheds novel light on the design and fabrication of adsorbent, which holds great potential for commercialization in recovering lead from battery industrial wastewater.

Efficient removal of p-nitrophenol from water by imidazolium ionic liquids functionalized cellulose microsphere

Removing p-nitrophenol (PNP) from water resources is crucial due to its significant threat to the environment and human health. Herein, imidazolium ionic liquids with short/long alkyl chain ([C2VIm]Br and [C8VIm]Br) modified cellulose microspheres (MCC-[C2VIm]Br and MCC-[C8VIm]Br) were synthesized by radiation method. To examine the impact of adsorbent hydrophilicity on adsorption performance, batch and column experiments were conducted for PNP adsorption. The MCC-[C2VIm]Br and MCC-[C8VIm]Br, with an equivalent molar import amount of ionic liquids, exhibited maximum adsorption capacities of 190.84 mg/g and 191.20 mg/g for PNP, respectively, and the adsorption equilibrium was reached within 30 min. Both adsorbents displayed exceptional reusability. Integrating the findings from XPS and FTIR analyses, and AgNO3 identification, the suggested adsorption mechanism posited that the adsorbents engaged with PNP through ion exchange, hydrogen bonds and π-π stacking. Remarkably, the hydrophobic MCC-[C8VIm]Br exhibited superior selectivity for PNP than the hydrophilic MCC-[C2VIm]Br, while had little effect on adsorption capacity and rate. MCC-[C8VIm]Br-2 with high grafting yield increased the adsorption capacity to 327.87 mg/g. Moreover, MCC-[C8VIm]Br-2 demonstrated efficient PNP removal from various real water samples, and column experiments illustrated its selective capture of PNP from groundwater. The promising adsorption performance indicates that MCC-[C8VIm]Br-2 holds potential for PNP removal from wastewater.

Cellulose-supported bioadsorbent from natural hemp fiber for removal of anionic dyes from aqueous solution

The aim of this study is to prepare an eco-friendly bioadsorbent by graft copolymerization and modification from hemp fiber including bio-macromolecules such as cellulose, hemicellulose and lignin for anionic dyes adsorption from aqueous solutions, and to investigate adsorptive properties. The prepared cellulose-supported bioadsorbent (TEPA-(GMA-g-HF)) was characterized in detail using SEM-EDX, STEM, FTIR, XRD, TGA and BET techniques and calculating the point of zero charge. It was used as an adsorbent to remove three different anionic dyes, Remazol Brilliant Blue R (RBBR), Reactive Red 120 (RR120) and Reactive yellow 160 (RY160) from the aqueous medium. The effects of adsorbent amount, pH, initial dye concentration, time and temperature on the adsorption were investigated. From the results, it was determined that the adsorption of all three dyes to the developed fibrous bioadsorbent was more compatible with the pseudo-second-order kinetic and the Langmuir isotherm model. It was found that the adsorption capacity increased with increasing temperature, and the adsorption capacity at 298 K was 91.70 mg/g for RBBR, 83.33 for RY160 and 76.34 mg/g for RR120, respectively. Dye removal efficiencies were provided as approximately 100 % at acidic pHs. This high removal efficiency has also achieved in the dense matrix medium, and even after five consecutive reused.

A novel porous hollow carboxyl-polysulfone microsphere for selective removal of cationic dyes

Herein, we obtained porous hollow carboxyl-polysulfone (PH-CPSF) microspheres through non-solvent-induced phase separation (NIPS) method and simple modification, used as highly efficient adsorbents for removing cationic dyes from sewage. The resulting PH-CPSF microspheres possess a hollow core and sponge-like shell structure, with high surface area, durable chemical inertness and structural stability. The as-synthesized PH-CPSF microspheres deliver a desirable adsorption effect after deprotonation treatment, with an adsorption capacity reaching up to 154.5 mg g^-1 at 25 °C (pH = 7) of methylene blue (MB). The inter-molecular interactions between MB and the surface of the PH-CPSF, including π-π interaction, hydrogen bonding, strong charge attraction and weak charge attraction endow the adsorption ability of the PH-CPSF. The pseudo-second-order kinetic model pronounces in the adsorption behavior, and the adsorption equilibrium data is fitted to the Langmuir model. Moreover, PH-CPSF microspheres can also be used as adsorption fillers for large-scale water purification, and a removal rate of 94.0% for MB can be achieved under a flow rate of 8000 L m^-3 h^-1. The reusability of 95.3% removal effect for PH-CPSF microspheres after 20 consecutive cycles can be attained by a simple regeneration treatment. The adsorption efficiency of the PH-CPSF microspheres was evaluated by variety of cationic and anionic dyes, with high adsorption capacity toward cationic dyes (100%) and less than 10% toward anionic dyes. These results manifest that PH-CPSF microspheres are a potential adsorbent with long-term purification capabilities, which are expected to be used in small and large-scale sewage treatment.