Synthesis of modified spent tea for aspirin adsorption in aqueous solution

Abstract

This present study focuses on the synthesis of a new modified eco-friendly adsorbent, spent tea (ST, discarded Camellia sinensis leaves), and its application in the adsorption of Aspirin from aqueous solution by batch adsorption technique. This is an effort in shifting towards new substitutes that are both inexpensive and highly efficient, such as agricultural waste materials as an alternative of the commonly used adsorbent material, activated carbon. The ST will first undergo an acid treatment using phosphoric acid, and subsequently modified with Polyethyleneimine (PEI) using Glutaraldehyde (GA) as the cross-linker. Aspirin removal efficiency was compared between the untreated spent tea (ST) and new PEI modified acid treated spent tea (TA-PEI). Effects of ratio of acid treated spent tea (TA) and PEI (1:1, 1:2,1:3, 2:1,3:1), and GA concentration (0,0.5,1.0,2.0,3.0, and 4.0 v/v%) were investigated. The optimal conditions for the synthesis of the modified adsorbent, TA-PEI are TA: PEI ratio of 1:2, and 0.5(v/v %) of GA. Afterwards, the untreated ST and TA-PEI were tested to determine the effect of contact time on Aspirin adsorption. It was found that TA-PEI shows great removal effectiveness-up to 64.70% before reaching equilibrium after 30min of contact time. Nevertheless, ST only shows removal of 1% and after 15min, there is no appreciable adsorption. These results suggested that TA-PEI has high potential to be used as an effective adsorbent for Aspirin removal. In the future, TA-PEI will undergo further research to investigate the effects of different adsorbent dosage, solution pH, initial concentration, solution temperature, and contact time. Several analysis (FTIR, SEM, CHNS, BET and point of zero charge) has to be done as well to get a better understanding of its properties and the adsorption mechanisms.