Adsorption mechanism modeling using lead (Pb) sorption data on modified rice bran-insoluble fiber as universal approach to assess other metals toxicity

• Published in: International journal of food properties Vol. 22; no. 1; pp. 1397 - 1410
• Main Authors: Qi, Jing, Li, Yue, Majeed, Hamid, Goff, H. Douglas, Rahman, Md Ramim Tanver, Zhong, Fang
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 01-01-2019; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: Adsorption; Calcium; Cation-exchange capacity; Dietary fiber; Heavy metals; insoluble fiber; Lead; Metals; pb2; Rice bran; Scanning electron microscopy; Sodium; Sorption; sorption isotherm; sorption kinetics; Sulfuric acid; Toxicity
• ISSN: 1094-2912; 1532-2386
• DOI: 10.1080/10942912.2019.1650764

The binding capacity of Pb on modified rice bran-insoluble fibers RBIF-0.2, RBIF-1.25, and RBIF-2.0 (0.2%, 1.25%, and 2.0% H
2
SO
4
with 1.25% KOH) having the variable specific surface area and cation-exchange capacity was evaluated. The Pb binding in terms of maximum binding capacity (BC
max
) with RBIF increased with pH (2-7). However, the presence of sodium and calcium reduced the binding of Pb to RBIFs. Further, adsorption kinetics followed pseudo-second-order kinetic model when fitted to real Pb sorption data. However, sorption mechanism data (scanning electron microscopy images) were well fitted to Langmuir model instead of Freundlich and Dubinin-Radushkevich that suggests monomolecular adsorption of Pb to RBIF (<8 kJ/mol). Moreover, negative ΔG and positive ΔH of Pb
2+
sorption confirmed the occurrence of spontaneous and endothermic process. The modeling of single-metal (Pb) data will be advantageous to use as a universal model for other heavy metals that will save the experimental costs. The data on all other heavy metals could be used with chosen models to elucidate their sorption mechanism to control the metallic-induced toxicity.