Colour removal from industrial wastewater using acid-modified tea leaves, a domestic waste

The dye-containing wastewater discharged from various industries such as textile, paint, paper, cosmetic, dye producing, etc. severely contaminate surface water and have detrimental effect on the environment as well as living organisms. In this present study, novel acid-modified tea leaves (AMTL) were synthesized from used tea leaves and used as a cost-effective biosorbent to remove anionic dye (Reactive Green 19, RG 19) from the effluent stream. The biosorbent was characterized by thermogravimetry, X-ray diffraction, Fourier transform infrared and scanning electron microscopy. Batch experiments for dye adsorption were carried out to analyse biosorbent dose, pH, stirring speed, temperature, contact time and initial dye concentration. Langmuir, Freundlich and Temkin isotherms were implemented to investigate and fit batch experimental data. The adsorption of RG 19 has followed Langmuir isotherm (R-2 > 0.988) with maximum adsorption capacity of 26.316 mg g(-1). Biosorption kinetics of RG 19 by AMTL has followed pseudo-second-order kinetic model (R-2 > 0.999). The values of Delta G degrees (-1.66 to 5.94 kJ mol(-1)) and Delta H degrees (70.764 kJ mol(-1)) demonstrated that the adsorption of RG 19 was spontaneous endothermic process.