Accelerated Sorption Diffusion for Cu(II) Retention by Anchorage of Nano-zirconium Dioxide onto Highly charged Polystyrene Material

Development of an acidized biochar-supported hydrated Fe(III) oxides for highly efficient cadmium and copper sequestration from water

Biochar-supported metallic oxides are attractive adsorbents for heavy metal cleanup, but the adsorption performance is still unsatisfactory as a result of the self-aggregation of the incorporated metallic oxides. A new hybrid nano-material was prepared through impregnating hydrated ferric oxide (HFO) nanoparticles within biochar bearing high-density charged oxygen-containing groups (e.g., carboxyl and hydroxyl groups) (ABC) derived from HNO₃ treatment. The as-made adsorbent, denoted as HFO-ABC, possesses highly dispersed HFO nanoparticles with typical size lower than 20 nm, and exhibits greater sorption capacity for Cd(II) and Cu(II) than the pristine biochar-supported HFO. It also shows great sorption preference toward Cd(II) and Cu(II) in co-presence of high levels of Ca²⁺, Mg²⁺ and humic acid (HA). Such prominent performance is put down to the high-density charged functional groups on the host ABC, which not only promote the dispersion of the immobilized HFO nanoparticles but also generate the potential Donnan membrane effect, i.e., the pre-concentration and permeation of target metals prior to their preferable adsorption by nano-HFO. The predicted effective coefficients of intra-particle diffusion for Cu(II) and Cd(II) are 3.83 × 10^-9 and 4.33 × 10^-9 cm²/s, respectively. HFO-ABC exhibits excellent performance for fixed-bed column application, and yields 513 and 990 BV effluents for Cd(II) and Cu(II) to achieve their discharge standards, respectively. The spent HFO-ABC could be in situ regenerated using binary HCl-CaCl₂ solution with desorption efficiency higher than 95%. All results manifest that increasing charged functional groups via HNO₃ treatment is an effective measure for boosting sorption performance of biochar-based nanocomposites.

Self-Assembled Naphthylidene-Containing Schiff Base Anchored Polystyrene Nanocomposites Targeted for Selective Cu(II) Ion Removal from Wastewater

Self-assembled composite adsorbents that combine the controllability of self-assembly with a mild operation process are promising for removal of heavy metal ions in wastewater. The design and preparation of functionalized composite adsorbent materials with multiple-site adsorption ability remain the most attractive in effectively removing heavy metal ions. Inspired by the macroporous structure of charged polystyrene (PS) resin and chelation of Schiff bases with heavy metal ions, smart composite adsorbents are constructed based on the combination and synergistic effect of multiple hydrophobic, π-π stacking, and electrostatic noncovalent interactions between polystyrene resin and naphthylidene-containing Schiff base (NSB). The resulting hybrid nanomaterials (PS-NSB) have uniform porous structures and well-defined and multiple target sites. These properties promote diffusion of the target ion, increase the binding site, and enhance the removal efficacy. This study offers a new strategy to harness a self-assembled Schiff base with integrated flexibility and multifunctions to enhance target metal ion specific binding and removal effects, highlighting opportunities to develop smart composite adsorbents.

Synthesis of ion-imprinted polymer-decorated SBA-15 as a selective and efficient system for the removal and extraction of Cu(ii) with focus on optimization by response surface methodology

Ion-imprinted polymer-decorated SBA-15 (SBA-15-IIP) for the adsorption of copper was synthesized and characterized using different techniques, including FT-IR, XRD, TG/DTA, SEM, BET, and TEM.

Single-Step Synthesis of Magnesium-Doped Lithium Manganese Oxide Nanosorbent and Their Polymer Composite Beads for Selective Heavy Metal Removal

Magnesium-doped lithium manganese oxide nanosorbent is prepared by a single-step solid-state method and characterized with appropriate analytical techniques, adsorption kinetic model, and isotherms. Competitive and noncompetitive adsorption studies are performed for a range of heavy metal ions. Prepared nanosorbent has shown explicit selectivity for various heavy metal ions and no remarkable influence of coexisting common interfering ions (Na⁺, K⁺, Mg²⁺, and Ca²⁺), which generally coexist with all natural sources of water, contaminated water, and industrial waste. To achieve easy handling of an adsorbent, polysulfone-nanosorbent (PS-nanosorbent) composite beads are prepared, and their competitive heavy metal removal performance is determined. Competitive adsorption and regeneration studies have shown that PS-nanosorbent beads can be employed for selective heavy metal removal and reuse for multiple cycles.

Effects of organic acids of different molecular size on phosphate removal by HZO-201 nanocomposite

Various organic acids in wastewater effluent could significantly influence the performance of phosphate adsorbent. This study focused on the effects of organic acids of different-molecular-size on phosphate adsorption by a novel nanocomposite HZO-201. Three organic acids (gallic acid (GA), tannic acid (TA) and humic acid (HA)) with distinct molecular size (HA > TA > GA) were chosen for this purpose. Both isotherm and kinetic tests of phosphate adsorption were conducted in the single-phosphate and binary system, and a series of microscopic techniques (i.e., XPS, FT-IR and SEM-EDX) and N₂ adsorption-desorption test were employed to explore the underlying mechanism. It was found that GA could greatly weaken phosphate adsorption capability of HZO-201 by directly competing for ammonium group on the nanocomposite, TA exhibited significant inhibition on phosphate adsorption rate mainly through pore constriction/blockage, while HA posed negligible impact on phosphate adsorption because of the size exclusion effect. It was also observed that although GA, TA and HA showed substantial influence on bulky HZO due to complexation, their impact on the nano-HZO loaded inside HZO-201 was little. The covalently bounded ammonium group and the networking pore structure of HZO-201 may play important roles in it.