P.B. SIBANDA, S. MAJONI, L.L. SIBALI AND H. CHIRIRIWA
Abstract
Layered double hydroxides were synthesised by a co-precipitation method with Mg/ Al ratio 2:1. The precursor LDH was calcined to produce mixed metal oxides which were used to remove the Titan Yellow dye by adsorption. The adsorbent was studied as a function of contact time, initial dye concentration, and adsorbent dosage using experiments in batch mode. The equilibrium sorption were fitted into Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich isotherms. Of the four adsorption isotherms, the R2 value of the Tempkin isotherm was the highest. The heat of sorption process established from Tempkin isotherm was 11.036 J/mol. Pseudo-first order, pseudosecond order kinetics and Elovich model parameters have been determined. The process of dye uptake follows second order kinetics with K2= 0.0242 mgg-1min-1 and R2 =0.9994. The results show that layered double hydroxides can be utilised as a substitute adsorbent to remove anionic dyes.