High-performance plastic-derived metal-free catalysts for organic pollutants degradation via Fenton-like reaction

The preparation of waste plastics-derived catalysts is an effective strategy for the waste reclamation. However, plastic-derived material is unsuitable for wastewater purification due to its small specific surface area (SSA) and inadequate active sites (such as N/O sites). Herein, we synthesized graphene-like nanosheets using g-C3N4 as the self-sacrificing soft template and plastic as the carbon precursor. Consequently, this strategy greatly promoted the efficiencies of the emerging organic pollutants degradation with the SSA and N content of the plastic-derived biochar increasing up to 1043.4 m2/g and 17.53 at.%, respectively. In detail, 100 % sulfadiazine (SD) removal could be achieved in 180 s via the activation of peroxymonosulfate (PMS) and the catalytic activity is far higher than previous research. Mechanism experiments corroborated that such a striking performance was attributed to the generation of SO4•-, O2•- and 1O2. Meanwhile, kinds of plastic precursors, even medical waste (i.e., masks, gauze, operating caps and degreasing cotton) were also applicable. And the practical application of the plastic-derived catalyst was further demonstrated by treating pollutants in a continuous flow mode with in situ fabricated membrane. This work provides valuable insights into waste plastics processing and water pollutants removal.

A novel hierarchical stiff carbon foam with graphene-like nanosheet surface as the desired adsorbent for malachite green removal from wastewater

A novel hierarchical stiff carbon foam (HSCF) was successfully prepared via a carbothermal reduction between the carbon foam with two-level pore structure and the Al₂O₃ from aluminum sulfate, and used as a bulk adsorbent for removing malachite green (MG) dye. The structures of the HSCF were characterized using SEM, XRD, FTIR, BET, and XPS, and the effects of adsorption condition on the MG removal were studied through batch adsorption experiments. Results show that large-sized and complex-shaped HSCF can be easily fabricated with a high compression strength of 1.58 MPa at a low bulk density (0.10 g cm^-3). The HSCF possesses a fluffy graphene-like nanosheet surface with a mesoporous structure and meanwhile exhibits good hydrophilicity loaded with aluminum hydroxide. The experimental maximum adsorption capacity for MG reaches 425.2 mg g^-1 with a relatively high partition coefficient of 9.38 mg g^-1 μM^-1 at the optimal condition. The experimental data are in good agreement with Langmuir isotherm and pseudo-second-order kinetic model, and meanwhile, the adsorption of MG onto the HSCF is a spontaneous and endothermic process. Also, the HSCF still exhibits good adsorption ability and stability after seven regeneration cycles.