Adsorptive removal of basic dyes from aqueous phase onto activated carbon of used tea leaves: a kinetic and thermodynamic study.

Activated carbon has been prepared from used tea leaves impregnated with H3PO4 (50%, w/v) and carbonized at 300 degrees C. Its adsorption capacity has been tested for the decolourisation of wastewater containing malachite green and methylene blue. The effect of system variables such as concentration, temperature, pH, contact time, adsorbent dosage and particle size was studied. The optimum pH range is 8-10 and dosage required is 1.2 g/L for 100% removal of both malachite green and methylene blue (100 mg/L). Break-through and exchaustive capacities for malachite green and methylene blue are 300.0 and 314.7 mg/g; 275.0 and 290.4 mg/g, respectively. The adsorption data follow Langmuir model as well as Freundlich model.