Removal of Basic Violet 10 from Neutral Aqueous Solution by Adsorption on used black tea leaves

Removal of Basic Violet 10 (BV-10) from aqueous solution by adsorption on used black tea leaves (UBTL) was studied in batch process. The effects of contact time, pH, concentration and temperature, etc. on adsorption have been investigated. The UV-visible spectrophotometric method was used to analyze BV-10 in solution at constant pH. From the optimization of solution pH, equilibrium adsorption experiments were carried out for different temperatures at pH 6.0. The experimental data are well expressed by Freundlich equation compare with Langmuir one. The maximum amount adsorbed calculated from Langmuir equation is 71.4 mg/g at 30 o C which is increased with increasing temperature which indicated endothermic nature of the process. The values of ∆G and ∆H confirmed that the adsorption of BV-10 on UBTL is spontaneous and chemical. The positive values of ∆S o suggested that an irregular increase of the randomness at the UBTL-solution interface during the adsorption process. The endothermic nature and the positive value of entropy of the adsorption might be due to the fragmentation of BV-10 molecules during the adsorption.