A comparative study on the utilization of berchemia discolour seed shell carbons and haycarb carbon for gold recovery

Abstract

A comparative analysis of the efficiency of activated carbon produced from Berchemia discolour seed shells derived activated carbon (BDSAC) and commercial grade activated carbon (Haycarb Carbon) was utilized in the adsorption of gold (iii) chloride from acidic medium. The adsorption process of BDSAC was best described by the Freundlich, Halsey, Dubinin-Radushkevich (D-R), Temkin isotherms and Langmuir isotherm had RL values in the range 0 < RL < 1 hence the adsorption process was favourable. The pseudo-second order, Spahn and Schlünder and Intra-particle diffusion kinetic model best described the kinetics implying that the rate-limiting step is sorption concerning valency forces through redox reaction between Au3+ and BDSAC dependent on the external diffusion of Au3+ in solution to BDSAC and the intra-particle diffusion of the molecules through a boundary layer of thickness 0.7042. The maximum removal capacity was determined as 100 % at an ionic strength of 0 M NaNO3, adsorbent dosage of 0.002 g/L and an initial concentration of 10 ppm. The removal capacity of Haycarb Carbon was also 100 %. BDSAC was found to be an efficient adsorbent as evidenced from its Freundlich exponent