Mechanochemical Activation of Serpentine for Recovering Ni (Ⅱ) from Wastewater

This is a paper in the field of metallurgical engineering. In this paper, natural clay mineral serpentine was subjected to mechanochemical activation (MA) for the highly-efficient removal of Ni (Ⅱ) in wastewater and simultaneous recovery of metal nickel as secondary resources. The effectiveness of serpentine for precipitation and recovery of Ni was investigated, with the process mechanism analyzed. The results showed MA of serpentine led to the disordering of the stable crystal structure of serpentine, thereby resulting in the release of large amounts of Mg²⁺ ions and hydroxyl group in aqueous solution, and the resultant interaction between Ni (Ⅱ) and OH-, with the formation of amorphous Ni(OH)₂ as sediments. The maximum processing capacity of activated serpentine for Ni (Ⅱ) reached up to 226.04 mg/g, meanwhile the final Ni (Ⅱ) concentration met up with the national discharging standard, indicating the feasibility of remediation of heavy metal contaminations by a very low dosage of activated serpentine. Concluded from these results, mechanochemical activation can be expected to boost the reactivity of natural serpentine, thereby improving the utilization efficiency of low-cost serpentine for the clean-up of environment pollutions and recovery of metal resources, which is conducive to promoting the green development of mineral-resource-environment cross-fields.