Electrochemical degradation of malachite green: Multivariate optimization, pathway identification and toxicity analysis

Abstract

Application of a newly developed electrode material, PbO2 coated on mild steel plate (MS-PbO2), for the degradation of malachite green (MG) by photocatalytic oxidation (PCO), electrochemical oxidation (ECO) and photoelectrochemical oxidation (PEC) was explored. PEC performed marginally better at lower current density. However, the performances of PEC and ECO were equally good at higher current densities. One variable at a time optimization was carried out to identify the major parameters influencing ECO. Multivariate optimization was carried out with NaCl concentration, current density and pH as the variables and chemical oxygen demand (COD) removal efficiency and current efficiency (CE) as the responses. Increasing the current density aided the COD removal efficiency, but decreased the CE. Low NaCl concentration and acidic pH were beneficial for both. The optimum condition for maximizing the COD removal efficiency and CE of MG (50 mg L(-1)) was obtained as NaCl concentration of 1.56 g L(-1), a current density of 1.91 mA cm(-2) and pH 5. The maximum predicted and experimental COD removal efficiencies were 89.41% and 90.8%, and CEs were 21.52% and 21.1%, respectively. Degradation intermediates were identified and a possible pathway of degradation was proposed. Disc inhibition study showed that the degraded samples are non-toxic. The efficacy of the method was tested for treating wastewater collected from dyebath having a COD of about 2000 mg L(-1). COD removal efficiency of greater than 90% was achieved within 12 h at a current density of 7.2 mA cm(-2).

Mathematical Modeling and Multivariable Optimization Design of SUV Chassis Structure Based on SFE CONCEPT

“…SFE CONCEPT uses a new, higher-resolution deformation technology. When the design model is modified, its limited component model will be automatically updated, and the network will also be automatically updated [19,20]. When it is detected that the quality of the grid does not meet the criterion requirements, a high-quality grid with various connection relationships can be generated in real time according to the new geometric model.…”

Combining Pickering Emulsion Polymerization with Molecular Imprinting to Prepare Polymer Microspheres for Selective Solid-Phase Extraction of Malachite Green

“…Malachite green (MG) is an N -methylated diaminotriphenylmethane dye widely used in the fish and dye industries due to its availability, low cost, and sterilization efficacy in killing bacteria and parasites [1,2]. On the other hand, a large number of studies have demonstrated that MG exhibits a high toxicity to organisms [1,2,3,4,5,6,7,8,9,10], and can pose a carcinogenic and mutagenic threat to humans through bio-enrichment [1,5,7]. Even worse, the recalcitrant nature of MG indicates that it can be enriched persistently in the organism body, causing a long-term toxicity [6].…”