Enhancement of Cd(II) electrosorption using electrosorption process with manganese oxide nanomaterial electrodeposited

Abstract The problem of water contamination by Cd(II) ions is considered as a major problem in the world. In this context, a clean, sustainable, soft and non-toxic approach was proposed based on the electrosorption process using electrodeposited pure manganese oxide on SnO2 subtract (Na-MnO2/SnO2) to remove Cd(II) ions without sludge formation like in the case of chemical and biological processes. Various characterization methods, such as scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and cyclic voltammetry were used to analyze the electrodeposited Na-MnO2/SnO2. The effects of the applied potential (0.0–1.0 V), electrodeposited charge quantities (Q = 0.45, 0.9, 1.5 and 3C) and the initial pH (2.0–9.0) on the electrosorption capacity of Cd(II) were examined and optimized. The highest electrosorption capacities were recorded for thin films with the lowest charge quantity (0.45C) and the highest Mn average oxidation state (3.84). Adsorption isotherms studies revealed that the nanomaterial (Na-MnO2/SnO2) has an electrosorption capacity of 2583.31 mg/g. The comparative study between the two techniques adsorption and electrosorption of Cd(II) by Na-MnO2/SnO2revealed the electrosorption to be better regarding the treatment kinetics and elimination capacity of Cd(II). During electrosorption, Na-MnO2/SnO2 with a charge of 0.45C released less manganese, indicating this process is more promising in capacity and stability. The nanomaterial got reused for several cycles. These low-cost efficient nanomaterials and methods are promising for the removal of heavy metals with a sustainable and environmentally friendly approach to produce clean water without secondary pollution or sludge formation.