Statistical Treatment of Bleaching Kaolin by Iron Removal

Abstract

In the present study, oxalic acid was used as a leaching reagent to remove iron from a kaolin mineral. Statistical analysis was conducted to determine the most influential factors in the dissolution of iron from the kaolin mineral. Our goal was ferric iron solubilization and its reduction to ferrous iron to improve the iron removal in the acid medium. Leaching experiments were conducted at atmospheric pressure. A two-level factorial design of the type 2<sup>4</sup> was utilized. The dependent variable was the percentage of dissolved iron, and the dependent variables in this study were acid concentration (0.35 and 0.50 M), temperature (75 °C and 100 °C), leaching time (2 and 4 h), and pH (1.5 and 2.5). An analysis of variance revealed that the effects of the factors temperature (b), pH (d), and the combined effects of temperature and time (bc) resulted in the maximum dissolution of iron of 88% at 100 °C, giving a kaolin mineral with a whiteness index 93.50%.

High-Efficiency Conversion of CO2 to Oxalate in Water Is Possible Using a Cr-Ga Oxide Electrocatalyst

“…All literature reports that reduce CO 2 to oxalate in organic or low-proton-activity solvents produce the oxalate dianion. The Cr-Ga system, which yields maximum oxalate Faradaic efficiencies around pH 4.1, generates a combination of monoanionic and dianionic oxalate . As shown in Text S1, relative quantities of the monoanionic and dianionic species were calculated at each pH tested, indicating that, at pH 4.1, the quantity of oxalate monoanion slightly exceeds that of the dianion.…”