The grafting of acrylic acid onto biosorbents: Effect of plant components and initiator concentration

Acrylic acid was grafted onto raw and Fenton's reagent treated pine cone using KMnO4 as initiator to determine the effect of plant organic components on grafting process. Concentration of the KMnO4 was varied between 0.0005 and 0.0200 mol/dm(3) and progress of the initiation process monitored using ORP and change in hydrogen ion concentration (Delta H+). The optimum ratio for Fenton's modification was Fe2+/H2O2 = 1/50 which corresponds to the highest leaching of plant components and having the least bulk density, ORP and Delta H+. It was observed that increasing KMnO4 concentration, reduced the MnO2 deposited on the pine surface, increased Mn3+ production in bulk solution while reducing grafting efficiency but increasing homopolymer formation. Radical formation on the raw pine cone was found to be lower as seen from the lower ORP and Delta H+ values observed at similar grafting conditions. Plant organic components was observed to affect the grafting efficiency and monomer conversion as observed from the weight increase, surface charge and FTIR analysis of the acrylic acid grafted Fenton's reagent treated pine and the raw pine. Optimum dye removal did not correspond to highest grafting efficiency. (C) 2012 Elsevier Ltd. All rights reserved.