Efficient recovery of botallackite Cu₂(OH)₃Cl from actual spent coppery etchant via pre-oxidation and neutralization-precipitation - Yulong Yi; Guojun Cai; Qi Zhang; Jue Yin; Jun Wu; Zixun Liu; Zhenyu Peng; Fubing Yao; Chong-Jian Tang (Journal of Water Process Engineering, 2026)