The removal of low concentration PPCPs from water is a challenging issue. A graphene hydrogel with 3D networks shows great potential for accelerating eddy diffusion of low concentration PPCPs. Herein, to further promote its molecular diffusion, a graphene/TiO2 nanowires (GNW) hybrid structure was implanted into graphene hydrogel. The as-prepared rGO/GNW hydrogel exhibited significantly enhanced adsorption–photocatalytic performance and excellent stability for low concentration ethenzamide, a typical pharmaceutical pollutant in water, under vacuum ultraviolet (VUV), ultraviolet (UV), visible and near-infrared light irradiation. When the initial ethenzamide concentration was 500 ppb and catalyst dosage was 10 mg/150 mL, ethenzamide was completely removed in 3 min and the corresponding photocatalytic apparent rate constant was 2.20 times that by GNW, 4.09 times that by rGO/P25 and 4.31 times that by rGO/NW under VUV irradiation, respectively, and its removal rate attained 99.0% in 120 min and the corresponding photocatalytic apparent rate constant was 2.06 times that by GNW, 3.34 times that by rGO/P25 and 17.42 times that by rGO/NW under UV irradiation, respectively. The GNW hybrid structure in the hydrogel played a vital role in overcoming the mass transfer resistance of low concentration PPCPs. The as-prepared rGO/GNW hydrogel exhibits significant potential for the removal of low concentration PPCPs from water.
Pharmaceuticals and personal care products (PPCPs) pose potential risks to aquatic ecosystems and human health. This work developed an ozonation-assisted electrochemical filtration (OAEF) system using a Ti 3 C 2 T x /CNTs composite membrane electrode and systematically investigated its efficiency, mechanisms, and practicality for PPCPs removal. The results suggest that the excellent adsorption and hydrophilic properties of Ti 3 C 2 T x , combined with its formation of an optimized membrane structure when mixed with CNTs, significantly enhanced the pollutant adsorption capacity and water permeation flux of fabricated electrode. Ozone incorporation in the electrochemical filtration process facilitated pollutant abatement, achieving approximately 99 % degradation and 42 % mineralization of fluoxetine (FLX), a representative PPCP. Moreover, the OAEF system demonstrated broad pH suitability and good stability, effectively detoxifying FLX-contaminated wastewater. The analysis of oxidants and electrode component evolution in the OAEF system, combined with density functional theory (DFT) calculations, revealed that enhanced mass transfer and electron transport promoted electro-peroxone initiation and reactive oxygen species (ROS) generation, thereby improving pollutant elimination and regenerating the adsorption capacity of electrode. Further analysis of 34 PPCPs treatment using quantitative structure-activity relationship (QSAR) models indicated that adsorption on the Ti 3 C 2 T x /CNTs was primarily influenced by pollutant solubility, C O bond content, dipole moment, and molecular weight, while degradation was significantly impacted by aromatic ring content, highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy, and solubility. Additionally, the Ti 3 C 2 T x /CNTs membrane electrode exhibited satisfied fouling mitigation during the treatment of real surface water, suggesting that the OAEF process is feasible for practical applications.
Pharmaceuticals and personal care products (PPCPs) are universally detected in natural waters, posing potential risks to drinking water safety. Nanofiltration (NF) is an advanced technology for water purification; however, its removals of PPCPs are unsatisfying, especially for hydrophobic species. In this study, the 3D architecture of nanomaterials were used to manipulate the performance the polyamide (PA) thin-film nanocomposite (TFN) membrane. In-situ addition of polyethyleneimine (PEI) successfully induced the assembly of ZIF-8 nanocrystals into star-shaped clusters (ZIF-8-PEI) due to the coordination between PEI and Zn 2+ . Together with the improved hydrophilicity, these ZIF-8-PEI clusters became excellent scaffolds for water drop retention after discretely loading onto the porous substrate. The conical protrusions of the ZIF-8-PEI clusters supported the defect-free PA film produced by the interfacial polymerization (IP), leaving big interfacial cavities underneath. These cavities worked as gutters for water transport, and the water permeance of the optimal TFN was 79% higher than that of the pristine thin-film composite (TFC) membrane. Moreover, the water impregnated cavities markedly alleviated the hydrophobic interaction between the PA film and hydrophobic PPCPs, impeding the transport of PPCPs across the membrane. Our results demonstrated the importance of the 3D architecture of nanofillers for the improving membrane performance.
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