Extraction, characterization and application of cellulose from pandan leaves as grafted flocculant for dyes treatment

Abstract

A new polyacrylamide grafted cellulose (PAM-g-cellulose) was successfully synthesised by using microwave assisted synthesis method. Cellulose was extracted from Pandan leaves by carrying out alkali and bleaching treatments. The determination of chemical composition was done which covers the percentage of lignin, hemicellulose and cellulose. Analysis of Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Thermogravimetric (TGA) were conducted to the raw Pandan leaves and extracted cellulose. For grafting synthesis study, the highest grafting percentage was achieved at 170%. The best grafted sample (i.e. highest percentage) then was characterized using SEM and FTIR. The PAM was successfully grafted onto the backbone of cellulose as confirmed by SEM and FTIR results. The grafting mechanism involved a synergism of microwave radiation and ceric ammonium nitrate (CAN) as chemical free radical initiator to initiate the free radical grafting reaction. The flocculation studies of the developed grafted copolymers have been evaluated in synthetic dye (Reactive Black 5 (RB5)) suspension. Response surface methodology (RSM) and Box-Behnken design (BBD) were employed to explore the relationship of process variables (i.e. initial dye concentration, flocculant dosage and pH) on percentage reduction of initial dye concentration and COD level of RB5 dye as well as to find the optimum process condition. The flocculant dosage and pH were the most significant factors in affecting the degree of flocculation efficiency. The optimum condition for reduction of initial dye concentration and COD were achieved at initial dye concentration of 0.03 g/l, flocculant dosage of 0.06 g and pH 11.72. Under this condition, the reduction of initial dye concentration and COD were 23.51% and 54.24%, respectively.