Activated carbon from tea residue as efficient absorbents for environmental pollutant removal from wastewater

Water pollution has become a major environmental concern for mankind. Although tea residue is usually discarded as waste, it can be used as a biological resource for the preparation of porous carbon for wastewater treatment. In this study, activated carbon (AC) was prepared from tea residue using ZnCl2, H3PO4, H2SO4, NaOH, and KOH. The effects of the preparation conditions were investigated, and the optimal conditions were determined by the iodine number of the ACs. ZnCl2-derived AC has the highest iodine number of 1519.0 mg/g compared with other activator-derived ACs. The results of an orthogonal test confirmed that the concentration of ZnCl2 is the most important factor for the preparation of ACs. The optimized AC possesses a well-developed microporous structure with a high specific surface area of 1029 m(2).g(-1) and a small pore size of 0.6589 nm. The AC exhibited a high adsorption capacity for heavy metals (removal efficiency of 99.9% for Hg and 74.7% for Cu), pigments, and pesticide residues (removal efficiency of 100.0% for 16 types of organic phosphorus pesticides). The adsorption mechanism was analysed using Fourier transform infrared spectroscopy. The AC with excellent adsorption performance provides promising potential for application in wastewater treatment.

Automated summary

Tea residue can be used to prepare activated carbon with excellent adsorption performance for wastewater treatment. ZnCl2-derived activated carbon shows the highest iodine number. The optimized activated carbon has a well-developed microporous structure and high specific surface area, providing promising potential for the removal of heavy metals, pigments, and pesticide residues.