Ca-Al-Containing Slag As an Advanced Fenton System for the Remediation of Acid Sulfate Soil

For the first time, an industrial solid waste (CAS) was used for the rapid oxidation and neutralization of acidic sulfate soil. The waste mainly contained Fe-doped CaCO3 and CaAl-layered double hydroxide (LDH). After treatment, CAS neutralized the acidic soil with the aid of hydrogen peroxide. Compared with other oxidation-accelerating materials, including activated carbon, biochar, and Fe-doped biochar, CAS showed the best oxidation rate acceleration. When the ratio of CAS and sulfur in acidic soil was 1.5:1, the pH of the soil changed to 6.32 and the oxidation rate increased by 50%. The characterization results showed that the main products of CAS were CaMg oxides and Ca-Al LDH. The oxidation product (SO42−) was intercalated into the LDH interlayers. The accelerated oxidation mechanism of CAS was divided into the following stages: accelerated Fenton oxidation; LDH adsorption of oxidized SO42−; and neutralization of sulfuric acid by calcium carbonate. The main results of this work provide a high-value-added utilization method of solid waste for acidic soil remediation.