Synthesis, characterization and cation exchange performance of chemically modified pineapple waste biomass for the removal of Fe(II) from water

A new biosorbent containing exchangeable calcium has been developed from waste biomass of pineapple fruit for Fe(II) removal by saponification with Ca(OH)2 in this study. Biosorbent characterizations and mechanism identification was done using field emission scanning electron microscopy (FE-SEM), enery dispersive X-ray spectroscopy (EDS), fourior transform infra-red (FTIR) spectroscopy, X-ray diffraction (XRD) measurement, and chemical analysis techniques. The total amount of exchangeable protons in H-SPWB was determined to be 2.54 mol H+kg-1. Biosorption of Fe(II) onto raw pineapple waste biomass (RPWB) and saponified pineapple waste biomass (SPWB) was strongly pH dependent and maximum biosorption occurred at pH 3.5 and 3, respectively. The experimental data of Fe(II) biosorption onto SPWB was fitted well with the Langmuir isotherm model and pseudo-second-order (PSO) kinetics. Maximum Fe(II) biosorption capacities of RPWB and SPWB using Langmuir isotherm model were found to be 100 and 125 mg g-1, respectively. Al(III) and Ca(II) caused minor interference whereas co-existing Zn(II) lowered Fe(II) uptake capacity of SPWB significantly. The trace concentration of Fe(II) exist in the water sample could be successfully lowered down to WHO stanndard (0.3 mg L-1) by using modified pineapple waste biomass. Fe(II) could be desorbed from spent Fe(II)-SPWB using HCl solution. Therefore, the biosorbnts investigated in this study can be employed as a low cost, environmentally benigh, and efficient biosorbent for the removal of trace amount of Fe(II) from contaminated water.