Characterization of activated carbon from waste tea (Camellia sinensis) using chemical activation for removal of methylene blue and cadmium ions

Abstract

The activated carbon based on waste tea (WT-AC) was prepared using sulfuric acid as an activating agent at different concentrations (5%, 10%, 20%, and 30%). Suitable characteristics as adsorbent have revealed concentration at 30% of waste tea activated carbon (WT-AC4) yield better adsorption, whereby other parameters including bulk density, ash content, volatile matter content, and moisture content obtained are 0.301 g mL−1, 3.40%, 26.76%, and 4.34%, sequentially. Overall, WT-AC samples have shown a well-developed porous structure and are declared an amorphous region. Comparatively, the results of adsorption studies reveal iodine value of WT-AC4 is 593.41 mg g−1 and commercial activated carbon is 738.62 mg g−1, while in 100 mg L−1 of methylene blue, the percentage of removal along with adsorption capacity yield the value of 89.2% (1.78 mg g−1) and 97.6 (1.98 mg g−1), respectively. In 0.5 mg L−1 and 1.0 mg L−1 of cadmium ions, WT-AC4 achieved 100% removal in both concentrations compared to commercially activated carbon with only 88.9%, then dropped to 46.2%. Significantly, the activated carbon from waste tea at a concentration of 30% sulfuric acid could be used as a low-cost adsorbent to remove organic and inorganic pollutants.