Facile synthesis of Poly(epichlorohydrin-diethylenetriamine) hydrogel for highly selective diclofenac sodium removal

Highly efficient and selective removal of anionic dyes from aqueous solutions using polyacrylamide/peach gum polysaccharide/attapulgite composite hydrogels with positively charged hybrid network

To avoid the weakness (lower adsorption rate and selectivity) of peach gum polysaccharide (PGP) and improve the adsorption performance of polyacrylamide (PAAm) hydrogel (lower adsorption capacity), in the present work, the PGP was chemically tailored to afford ammoniated PGP (APGP) and quaternized PGP (QPGP), and attapulgite (ATP) was bi-functionalized with cation groups and carbon‑carbon double bond. Then, PAAm/APGP and PAAm/QPGP/ATP hydrogels were synthesized via redox polymerization. The synthesis procedure and properties of hydrogels were traced by FTIR, SEM, XPS, TGA, TEM, and BET methods, and the dye adsorption performance of the hydrogels was evaluated using the new coccine (NC) and tartrazine (TTZ) aqueous solutions as the model anionic dyes. Effects of initial dye concentration, pH, and ionic strength on the adsorption were investigated. Compared with PAAm/APGP hydrogel, PAAm/APGP/ATP hydrogel exhibits higher adsorption rate, superior adsorption capacity, stability, and selectivity towards anionic dye. The adsorption process of PAAm/QPGP/ATP hydrogel reached equilibrium in about 20 min and followed the pseudo-second-order kinetic model and Langmuir isotherm. The adsorption capacities towards NC and TTZ of PAAm/QPGP/ATP hydrogel were calculated as 873.235 and 731.432 mg/g. This hydrogel adsorbent originating from PAAm, PGP, and ATP shows great promise for application in practical water treatment.

Ultra-efficient adsorption of diclofenac sodium on fish-scale biochar functionalized with H3PO4 via synergistic mechanisms

Developing safe and efficient diclofenac sodium (DS) removal technology has become a critical issue. This study synthesized the fish-scale biochar by co-pyrolysis of fish scale and phosphoric acid (H₃PO₄). In addition to increasing the specific surface area and pore volume of fish-scale biochar, H₃PO₄ assisted in the formation of Graphitic N and sp² C, as well as reacting with C═O groups to form a significant number of phosphorus-containing groups. All these functional groups could act as major active sites for DS adsorption. Adsorption data could well fit pseudo-second-order and Langmuir models. The maximum adsorption capacity of FSB_600-15 for DS was 967.1 mg g^-1, which was much better than that reported in the literature. Under the synergistic effect of various mechanisms (pore-filling effect, electrostatic attraction, H-bonding, π-π, and n-π electron donor-acceptor interactions), the DS ultra-efficient adsorption on FSB_600-15 was realized. Meanwhile, the DS adsorption by FSB_600-15 was an endothermic, spontaneous, and entropy-increasing process. Furthermore, the DS adsorption capacity was more than 426.5 mg g^-1 in the actual water, which was sufficient for practical applications.

Design strategy of self-assembled BC@MIL-100(Fe) composite membrane for the efficient removal of diclofenac sodium from water

Pharmaceuticals and personal care products (PPCPs) as typical emerging pollutant have attracted extensive attention due to the risks to human health and environment. As a kind of harmful PPCPs, diclofenac sodium (DCF) has been frequently detected in water environment, which needs to be removed effectively. Herein, we successfully fabricated network structure composite membranes consisting of one-dimensional (1D) well-defined core-shell bacterial cellulose (BC)@MIL-100 (Fe) nanofibers by a simple but effective step-by-step strategy. The BC@MIL-100(Fe) composite membrane has three-dimensional network utilizing bacterial cellulose nanofiber as template, which was observed as the MIL-100(Fe) grew on the nanofiber uniformly and obvious core-shell structure. Impressively, the BC@MIL-100(Fe) not only possessed favorable architecture but also behaved good properties to adsorb DCF from water. As we expected, the as-obtained BC@MIL-100(Fe) composite membrane exhibited convenient recycling, high chemical stability, and short equilibrium time (30 min) with high adsorption capacity (296 mg g^-1). Strikingly, in low DCF concentration solution, BC@MIL-100(Fe) composite showed high adsorption efficiency in periodic test, which can still reach 70% after five successive adsorptions without desorption. The results demonstrated that the adsorption mechanism may involve π-π interaction, H-bond interaction, and electrostatic interaction. This work proposes the new finding to understand the removing of DCF from water environment.