The Effect of NaOH-Na2CO3 Precipitation Bath Concentration on Adsorptive Performance of Crosslinked and Non-crosslinked Chitosan Beads for Azo Dye Removal

Abstract

AbstractThe newly formed chitosan (CS) gel beads were primarily synthesized in a precipitation bath which contains 1 M NaOH and Na2CO3 at varied concentration (0.2, 0.4 and 0.6 M). The CS gel beads formed with 0.2 M Na2CO3 exhibited the highest porosity (ε%) (97.10%) and dye uptake% (64.34%) after 72 h. Besides, the porosity and adsorptive performance for CS gel beads with 0.4 M and 0.6 M Na2CO3 were lower as compared to the pure CS gel beads due to low interconnection density caused by the deeper pores. To counteract the destabilizing effect, glutaraldehyde (GA) solution was added to the CS gel beads for chemically crosslinking. As result, all the GA-CS beads demonstrated noteworthy dye uptake% up to 99.6% after 4.5 h with disregards of precipitation bath concentration. This study had proven on the stabilising effect provided by GA crosslinking on the outstanding methyl orange (MO) adsorptive performance.KeywordsAdsorptionAzo dyeChitosanPrecipitationPorosityBatch mode