Tea is wide spread drink in the world. After drink tea soup, tea leaf residues are produced. The residues contain ligening, cellulose and propectinare with a net-like structure that could be used as biosorption material. They exhibit well adsorption performance for heavy metal and dye removal. Activated carbon is a commercial used biosorption material and have a well adsorption performance for heave metal and dye.
In this study, we used methylene blue (MB), a typical component of dyeing wastewater, as an indicator to test dye adsorption by tea leaf residues, activated carbon and other agricultural residues (rice husk and coffee residues). Samples were crushed to pass through a 60-mesh sieve for obtaining the desired particle sizes. Aqueous phase MB concentration was analysed using a UV-visible spectrophotometer at 664 nm. Regeneration efficiency were using NaOH as a desorbing agent to remove adsorbed MB. After washed, the residues reuse to adsorb new MB solution.
Results showed (1) adsorption capacity of activated carbon and tea leaf residues had higher than rice husk and coffee residues. (2) Tea leaf residues have high efficiently after 4 cycles (maintain 94% of the first cycle) using NaOH as a desorbing agent, and activated carbon had decrease efficiency gradually after 2 cycles. However, rice husk and coffee residues were low efficiently after 1 cycles. Because activated carbon production need complicated tectnology and higher cost, and tea leaf residues are easy produce and reuse the waste. This work shows that tea leaf residues are high efficiently and friendly to the environment.