KINETICS AND EQUILIBRIUM ADSORPTION STUDIES OF REMOVAL OF ANIONIC DYES FROM WATER USING CALCINED LAYERED DOUBLE HYDROXIDESP.B. SIBANDA, S. MAJONI, L.L. SIBALI AND H. CHIRIRIWAAbstract 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. |