Enhanced Arsenic (III) adsorption from aqueous solution by magnetic pine cone biomass

Enhancement of As(III) adsorption by magnetite immobilized on pine cone (MNP-PCP) as compared with pine cone (PCP) was studied. The adsorbents were characterized using FTIR, VSM, XRD and XPS. The PCP, MNP, MNP-PCP and physical mixtures of PCP and MNP (1:1, 2:1 and 1:2) were evaluated for As(III) adsorption. The results show that the composite had better As(III) uptake, FTIR peaks at 812 to 813 cm(-1) show As-O bonding. Pseudo second-order model and Langmuir isotherm gave good fit with the experimental data and monolayer capacities of PCP and MNP-PCP were 14.83 and 18.02 mg/g at 299 K. The adsorption type was found to be ion exchange as obtained from Dubinin-Radushkevich parameter E with values of 11.7 and 12.13 kJ/mol for PCP and MNP-PCP, respectively at 299 K. A slight increase in As(III) uptake with increasing ionic strength and shift in pH(PZC) to lower values after As(III) uptake which was higher for MNP-PCP confirmed the participation of ion exchange reaction.PO43- anions only caused a reduction in As(III) uptake which was stronger in MNP-PCP. HCl and NaOH desorbed a higher percentage of As(III) from MNP-PCP (82 and 66%) and MNP-PCP gave a more stable As(III) capacity after three cycle desorption/reuse.