Grafting of tea waste with polyacrylic acid and its potential applications

The indigenous materials such as tea waste were exploited as antimicrobial adsorbent for removing heavy metal ions. It was well known that tea waste was characterized with biodegradability and environmental-friendly product. Grafting copolymerization of acrylic acid onto tea waste was carried out using gamma radiation. The effects of solvent, dose and feeding concentration of acrylic acid have been investigated to achieve the optimum conditions. Grating (%) ranged from 30 to 70 for DMSO and H₂O, respectively. The grafted tea waste was characterized by Fourier transform infrared (FTIR) spectroscopy, swelling study, scanning electron microscopy (SEM) and energy dispersive spectrometry X-rays (EDS). The grafted samples were used in waste water treatment to remove heavy metal ions (Cr³⁺, Pb²⁺ and Hg²⁺). The highest adsorption capacity was 35 and 200 mg/g of Hg⁺² ions for ungrafted and grafted samples, respectively. The results showed that the selectivity among these metal ions is different onto tea waste-graft-polyacrylic acid. The grafted tea waste samples, which complexed with Cr³⁺, Pb²⁺ and Hg²⁺ ions, were found to have antimicrobial features. Therefore, they could be used as adsorbent in removing heavy metal ions with antimicrobial features as well.