Sorption of zinc by hydrogel palm kernel shell biochar blended with coal fly ash / Nurul Farhana Ahmad

Zinc is known to be an essential element for human health and its low intake leads to retardation in growth. However, high accumulation of zinc in humans may cause gastro intestinal distress, lung disorders, metal fume fever, abdominal pain and even cancer. The threats that are generated from zinc contaminated water can averted by adsorption technique using low-cost adsorbents. Hydrogel is three-dimension (3D) hydrophilic polymer that is chemical or physical crosslinked which has ability to swell rapidly and retain large volumes of water in their swollen structure. Recently, hydrogel has been a focus of researcher due to the good at absorbing heavy metal from aqueous state. In this research, hydrogel biochar is derived from palm kernel shell biochar (PKSB) blended with coal fly ash (CFA) using ratio of palm kernel shell biochar (PKSB) to CFA (0.2:0.8, 0.5:0.5 and 0.8:0.2). Hydrogel palm kernel shell biochar blended with coal fly ash (HPKSB-CFA) composite is successfully synthesized by embedding the biochar into acrylamide (AAM) as monomer, with N,N'-Methylenebisacrylamide (MBA) as crosslinker and ammonium persulfate (APS) as initiator. While activated carbon (AC) remains an expensive material, HPKSB-CFA is attracting great interest for its use in the absorption of organic contaminants due to its low material cost and importance as renewable source for securing future energy supply in the environmental system. The aim of this study is to characterize HPKSB CFA by performing several analyses such as the Thermogravimetric Analyzer (TGA), Elemental Analyzer (EA), Brunaeur-Emmett Teller (BET) and Field Emission Scanning Electron Microscopy (FESEM), to investigate the performance of zinc removal by HPKSB-CFA in solution by using several parameters and to adopt the kinetic model from Langmuir and Freundlich isotherm. From the analyses, the results is describe 0.8:0.2 gives the best characteristic as excellent adsorbent. Further results of zinc removal obtained the best adsorbent of HPKSB-CFA is 0.8:0.2 weight ratio for all parameters studied. The percentage removal of zinc for adsorbent dosage, initial concentration and contact time are 95.6% removed by 2 g of HPKSB-CFA, 95.6% remove at lOmg/L initial concentration and 94.9% removed at 30 minutes for contact time. The experimental data was best fitted well to Langmuir isotherm meanwhile, the kinetic data was best described pseudo second order with a correlation coefficient (R2 ) 0.9997. Based on the analysis, it was found that the monolayer adsorption capacity was 37.52 mg/g for adsorption of zinc on HPKSB-CFA. Based on the results, HPKSB-CFA has a great potential to be applied as adsorbent to remove heavy metal in wastewater.