treatment of gold ore cyanidation wastewater by adsorption onto a hydrotalcite-type anionic clay as a novel adsorbent

The treatment of cyanide contaminated wastewater from a gold processing plant was performed by the synthesized nanostructured layered double hydroxide (ldh) which has known as a hydrotalcite-type anionic clay. ldh was synthesized by the co-precipitation process, characterized by x-ray fluorescence (xrf), x-ray powder diffraction (xrd), scanning electron microscope (sem) brunauer-emmett-teller (bet), fourier-transform infrared spectroscopy (ftir) and wavelength dispersive x-ray analysis (wdx) and applied for removal of free cyanide from both synthetic solution and mining effluent. the maximum particle size of synthesized ldh was determined to be 4 nm based on the scherrer’s equation. the maximum loading capacity of ldh, 60 mg/g, indicates that ldh is an interesting adsorbent for cyanide removal. the data modeling showed that the kinetic and equilibrium data best fitted by fpkm and rpim, respectively, also, rate-controlling step in the adsorption process is intra-particle diffusion based on weber–morris plot, and the adsorption of cn− onto ldh is a two-step process. the thermodynamic studies confirm that the adsorption of free cyanide on mg/al ldh is a spontaneous and endothermic process. the energy of activation for adsorption of free cyanide on mg/al ldh was determined to be 6.14 kj/mol, which is in the range physicochemical sorption. the mining wastewater treatment was performed by the synthesized ldh. the adsorption experiments showed that more than 90% of free cyanide was removed from the real solution during a short period of contact time, which confirms the ability of ldh for the treatment of industrial cyanide contaminated wastewater.