A facile approach to develop industrial waste encapsulated cryogenic alginate beads to sequester toxic bivalent heavy metals

Abstract

Herein, a solid industrial waste management approach converting silico-manganese fumes (SMF) waste to SMF impregnated cryogenic alginate beads (SMFCAB) and its applicability to remove potentially toxic cadmium Cd(II) and lead Pb(II) was proposed. Infra-red, elemental, and XPS analysis data supported the formation SMFCAB. Morphologically, pristine SMFCAB surface was synonymous to cauliflower with agglomerated and interconnected particles. The respective XPS spectral peaks for Cd(II) and Pb(II) at 408 and 144.5 eV binding energies confirmed their adsorption on SMFCAB. The adsorption was pH dependent, with maximum uptakes at pH: 5.5 (for Pb(II)) and 7.2 (for Cd(II)). Contact time studies depicts comparatively rapid Pb(II) adsorption, accomplishing 72% adsorption in 10 min, while only 50% Cd(II) adsorption was accomplished within same time slot. The adsorption data at varied temperatures was fitted to Freundlich isotherm model, while kinetics data was fitted to pseudo-second-order model. Exothermic adsorption process with maximum monolayer adsorption capacities (qm) on SMFCAB were 200 mg/g (for Pb(II)) and 178.6 (for Cd(II)) at 298 K. Hydrochloric acid (0.01 M) eluted maximum amount of metal ions. Keywords: Waste management, Silico-manganese fumes, Cryogenic beads, Heavy metals, Adsorption