External optimization of Zr-MOF with mercaptosuccinic acid for efficient recovery of gold from solution: Adsorption performance and DFT calculation

•A novel sulfydryl-modified MOF was prepared by externally optimization methods.•The theoretical adsorption capacity of Au(III) was increased by almost 24.57%, and the reaction kinetics was also accelerated by more than 180%.•In the existence of competing ions, Au(III) recovery was enhanced by 26.53%.•The adsorption mechanisms were electrostatic interaction, reduction and chelation.•DFT calculation revealed that sulfhydryl functional group was the strongest binding site.