Single-stage solution combustion preparation of ZnFe2O4-ZnS nanoparticles as dye adsorbent: Effect of fuel to oxidant and Zn to Fe molar ratios

ZnFe2O4-ZnS adsorbent was synthesized by the single-stage solution combustion procedure applying the thiourea at different fuel to oxidant ratios (ϕ = 1, 1.2, 1.4, and 1.6), and different Zn to Fe molar ratios (Zn : Fe = 0.5, 0.6, 0.7, and 0.8). The efficiency of the removal of methyl orange dye by synthesized powders in various conditions was investigated. The best sample, in terms of dye removal, was the synthesized powder at Zn : Fe = 0.6 and ϕ = 1.4. Dye removal was discovered to be extremely pH-dependent. The highest dye removal was observed to be about 94% of methyl orange, which disappears after 20 min in a dark environment. Kinetics investigations were carried out to discover the mechanism of methyl orange elimination and its adsorption rate kinetics. It was found that the elimination of methyl orange by ZnFe2O4-ZnS powders follows a pseudo second-order adsorption kinetics model.