Immobilized enzyme bioremediation is a promising technique for eliminating pollutants to alleviate water scarcity pressure but is severely hindered by poor enzymatic activity and stability. An effective charge-assisted H-bonding approach is developed to achieve high laccase loading and enzymatic activity on bio(cellulose)-based hydrogels. Notably, this strategy can be readily extended to lipase and catalase. The bio-based hydrogels are synthesized by grafting deoxyribonucleic acid onto the cellulose backbone through a one-step structural regulation, achieving high mechanical strength, enzyme loading and contaminant capture for degradation. The biocompatible laccase-immobilized hydrogels exhibit significant removal and degradation performance for diverse organic micropollutants, including parent and substituted polycyclic aromatic hydrocarbons, per- and polyfluoroalkyl substances, antibiotics and organic dyes. Further testing focused on parent and substituted polycyclic aromatic hydrocarbons shows minimal influence of various co-existing interfering substances on performance of the laccase-immobilized bioactive hydrogel, with its contaminant removal and degradation efficiency in authentic wastewater being 93.0- and 64.3-fold that of commercial free laccase, respectively. This work provides an effective strategy for sustainable bioremediation of wastewater and other pollutant streams, while simultaneously enabling the development of innovative enzyme catalysts.

Enzyme-catalyzed biodegradation is an emerging green strategy for environmental remediation, although challenged by high cost and poor robustness. Herein, natural biopolymer (cellulose)-derived hydrogels concurrently doped with β-cyclodextrin and montmorillonite nanosheets that are synthesized in one-step demonstrate exceptional pollutant affinity and mechanical strength. Laccase is then stably and effectively assembled onto the hydrogels by a facile strategy based on charge-assisted H-bonding, which can be extended to other enzymes. The advanced laccase-assembled hydrogels display excellent stability and increased degradation activity achieved by strong substrate capture and rapid electron transfer. The laccase-assembled hydrogels exhibit significantly improved removal (62-fold) and degradation (52-fold) performance compared to free laccase for diverse organic pollutants (e.g., polycyclic aromatic hydrocarbons) in real wastewater. This enhanced performance is maintained despite the presence of heavy metals, other organic chemicals or dissolved organic matter. This work provides a practical strategy for designing an advanced and sustainable biodegradation tool for environmental remediation.

Herein, the adsorption/desorption behaviors of benzoic acid (BA) and phthalic acid (PA) on three functionalized carbon nanotubes (CNTs) at various pH were investigated, and the charge-assisted H-bond (CAHB) was verified by DFT and FTIR analyses to play a key role. The results indicated that the adsorption order of BA and PA on CNTs was different from K_ow of that at pH 2.0, 4.0, and 7.0 caused by the CAHB interaction. The strength of homonuclear CAHB (≥78.96 kJ·mol⁻¹) formed by BA/PA on oxidized CNTs is stronger than that of heteronuclear CAHB formed between BA/PA and amino-functionalized CNTs (≤51.66 kJ·mol⁻¹). Compared with the heteronuclear CAHB (Hysteresis index, HI ≥ 1.47), the stronger homonuclear CAHB leads to clearly desorption hysteresis (HI ≥ 3.51). Additionally, the contribution of homonuclear CAHB (≥52.70%) was also greater than that of heteronuclear CAHB (≤45.79%) at pH 7.0. These conclusions were further confirmed by FTIR and DFT calculation, and the crucial evidence of CAHB formation in FTIR was found. The highlight of this work is the identification of the importance and difference of pH-dependent homonuclear/heteronuclear CAHB on the adsorption and desorption behaviors of ionizable organic compounds on carbonaceous materials, which can provide a deeper understanding for the removal of ionizable organic compounds by designed carbonaceous materials.

To significantly enhance the unsatisfactory Au(III) sorption performance (2280 mg g⁻¹) by a material designed in our previous work, we ingeniously fabricated a nano-sized and uniform molybdenum composite (MoCOM) using a household microwave oven; it was embedded in a nanofiber mat by electrospinning technique to synthesize a novel material (CS-MoCOM-Th) for effective Au(III) sorption. After embedding MoCOM, an ultrahigh maximum sorption capacity (4090 mg g⁻¹) of Au(III) at high concentrations and a sorption efficiency at low concentrations by CS-MoCOM-Th (99.59%) were achieved at pH 4.0. Mechanistically, the excellent Au(III) sorption performance was mainly driven by electrostatic attraction by protonated C–N⁺ groups and coordination interaction with N- or S-containing moieties: C–N, CN, C–N⁺, CS, S(−II), and S_n(−II). During sorption, 69.42% of Au(III) was directly reduced to elemental gold on CS-MoCOM-Th, and gold foils precipitated on the nanofiber mat. Notably, excellent sorption selectivity of Au(III) on CS-MoCOM-Th was achieved when heavy metals, including Cu(II), Ni(II), Pb(II), and Zn(II), and noble metal Pt(IV) were co-present at 2 × 10⁻³ mg mL⁻¹. CS-MoCOM-Th could still sorb 82.15% of Au(III) at 0.01 mg mL⁻¹ after four cycles. Overall, this study highlights that CS-MoCOM-Th is one of the most competitive candidates for Au(III) recovery from the aqueous phase.