Self-propagation combustion method for the synthesis of solar active Nano Ferrite for Cr(VI) reduction in aqua system

Abstract

Abstract The study aimed at the development of a facile route to the synthesis of a solar active nano ferrite via the self-propagation combustion protocol. The solar activity of the synthesised ferrite sample (FSP) was determined using the reduction of Cr(VI) to Cr(III) as a case study, in the presence of oxalic acid, as the hole scavenger. The analysis of the time-concentration profile data of the photoreduction reaction with the pseudo first order kinetic equation showed that the rate and half-life (t1/2) of photoreduction of Cr(VI) to Cr(III) is dependent on the initial Cr(VI) concentration. The photoreduction efficiency (PE) (%) of the FSP is a function of the initial FSP dosage and the hole scavenger. The determination of the influence of hydrochemistry on the PE (%) showed that Cr(VI) solution pH and ionic strength had no visible negative impact. Aside the presence of carbonate in the Cr(VI) solution, other anionic interfering species (i.e. NO−3, Cl− and SO3 2−) had minimal or no visible influence on the PE (%) values. The presence of carbonate, at higher concentration (i.e. ˃10 mg/L) significantly impacted on the PE values and hyperchromic shift in the absorbance values of the treated water from the photo reduction process was observed. The tendency of the Cr(III) that is formed from the photoreduction reaction to form Cr(III)-oxalato complex was confirmed after a certain minimum time of the photoreduction process.