Search

A versatile, eco-friendly synthesis scheme was developed to fabricate a series of hierarchically-structured CuBi2O4 composites for environmental applications. By simple tuning of the synthesis protocol (i.e. controlling the ethylene glycol to water ratio in the reaction matrix and employing different auxiliary metal precursors consisting of Cu2+, Co2+ or Fe3+ species), deposition of various metal oxides on CuBi2O4 was achieved. The proposed one-pot synthesis protocol utilizes the fast nucleation and controlled growth kinetics of CuBi2O4 to deliberately immobilize the desired metal oxides on the surface of the CuBi2O4. The manipulation of the diffusion rate, mass transfer kinetics and atomic mobility of the metal precursors by controlling the viscosity and dielectric properties of the reaction matrix lead to the formation of different CuBi2O4 composites with the desired properties. The synergistic coupling effect between the CuBi2O4 and deposited metal oxide contributed to the superior performance of the novel CuBi2O4 composites. The CuBi2O4 composites demonstrate excellent potential for various environmental applications such as being a catalyst for generating sulfate radicals from peroxymonosulfate for organic pollutant removal in water and being a disinfectant. The proposed green synthesis protocol is simple and offers flexibility for fabricating hierarchically-structured CuBi2O4 composites with enhanced properties for targeted applications. Accepted version

A series of surfactant encapsulated heteropolyanions (SEH-n) based on molybdovanadophosphates (MVPs) was prepared. The morphological optimisation of the SEHs was studied by the control of solvent polarity and MVP to surfactant ratio used. Investigation by TEM revealed the formation of particles with multi-lamellar nano-structure in the SEHs. Characterization of the SEHs by XRD, TGA and FTIR indicated the successful encapsulation of the molybdovanadophosphates with the surfactant. The performance of SEHs as catalysts for the removal of bisphenol-A under ambient conditions was evaluated. Factors influencing the performance of the SEH-n are the relative stability of the Keggin structure and electron accepting property. The dissolved oxygen plays a crucial role in improving the BPA removal efficiency. The hydrophobic property of the nano-sized SEHs provides good aqueous stability and allows excellent recoverability of the catalyst from the aqueous solution after treatment.

A novel dipicolinic acid-functionalized hematite (DPA-hematite) with high surface area was prepared by co-precipitation of a Fe(III)–DPA complex. It was used as a catalyst to activate peroxymonosulfate (PMS) for bisphenol A (BPA) detoxification. The XRD, FESEM, TEM and FTIR characterization indicated that nano-sized DPA-hematite with aggregated quasi-nanosphere morphology was obtained with a 1 : 1 ratio of Fe(III) to DPA. Higher catalytic activity of DPA-hematite over other Fe(III)-based catalysts was observed for BPA oxidation in the presence of oxone. The kinetics of BPA removal was investigated using a kinetic model with BPA concentration, initial oxone dosage and surface area of DPA-hematite. For the first time, the acute toxicity of BPA solution over time with elimination of oxone toxicity interference was studied using Vibrio fischeri bacteria and the results indicated that the evolution of acute toxicity was highly dependent on the initial oxone dosage. Under deficit oxone conditions, BPA was completely transformed to by-products along with decreased intrinsic toxicity but ring-opening reactions were barely observed which can be explained based on the dimerization–mineralization degradation pathways. Under excess oxone conditions, the intrinsic toxicity of BPA solution decreased along with ring-opening reactions leading to a greater extent of mineralization. The DPA-hematite can be reused for BPA detoxification for at least three cycles in the presence of 2.0 g L−1 oxone. Accepted version