Kinetics and redox copolymerization of acrylonitrile grafted palm seed powder after chemical modification with hydroxylamine as adsorbents for methylene blue removal

Abstract

In this research the potentials of palm seeds powder (PSP) as an alternative and environmental friendly adsorbent for the treatment of dye-methylene blue (MB) in waste water was explored. Also, the copolymerization of acrylonitrile (AN) onto palm seeds powder (PSP), using sodium persulphate (SPS) and potassium persulphate (KPS) as initiators were successfully carried out via redox copolymerization method under optimum conditions. The optimum conditions of grafting efficiency and grafting yield were achieved within 2 h and 40 reaction time. Afterwards, grafted product was chemically modified using hydroxylamine hydrochloride in order to convert the nitrile into oxime functional group. The characterization of poly(AN-g-PSP) and amidoxime –modified (AN-g-PSP) were done using: Fourier Transform Infrared (FT-IR) Spectroscopy, Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscope (SEM) . All the results from the characterization techniques shows that the copolymerization of PSP onto PAN and subsequently modification of poly(AN-g-PSP) using hydroxylamine hydrochloride were successfully carried out. The influence of pH, contact time and initial metal concentration towards adsorption of MB onto amidoxime-modified poly(AN-g-PSP) were investigated via the atomic absorption spectroscopy (AAS). The optimum removal of MB onto amidoxime-modified poly(AN-g-PSP) was found to be 97% (16.03 mg/g). Kinetic and thermodynamic studies were investigated, pseudo second-order was observed to be the most suitable that describes the adsorption process R² (0.998). Values obtained from thermodynamic analysis shows that the adsorption process is endothermic, spontaneous and chemisorptions in nature.