Chemically modified jackfruit leaves as a low-cost agro-waste adsorbent for Pb(II) removal from synthetic wastewater

Abstract

There is an emerging need to develop an economical, efficient and agro-waste-based adsorbent for the removal of toxic heavy metal ions from various aqueous media. In the present investigation, jackfruit leaves (Artocarpus heterophyllus) have been chosen as a suitable agro-waste-based material for the efficient removal of Pb(II) from wastewater. The surface modification of jackfruit leaf powder (JLP) has been done by chemical modification with 20% isopropyl alcohol followed by treatment with (i) alkali-sodium hydroxide (AIJLP) and (ii) tartaric acid (TIJLP). In comparison to JLP depicting BET surface area of 29 m2/g, the chemical modification resulted in about a 1.5-fold increase and 2.5-fold increase in the surface area of TIJLP (50 m2/g) and AIJLP (72 m2/g), respectively. Therefore, batch experiments were performed for Pb(II) adsorption using AIJLP for the optimization of equilibrium conditions viz., Pb(II) concentration, pH and contact time. Under optimized conditions, AIJLP showed a loading capacity of 87.7 mg/g from the Langmuir model at pH 5.0. Kinetic data were best fitted with a pseudo-second-order model. The characterizations of the adsorbents have been performed by FESEM with EDX, FTIR, TGA, XPS and surface area analyzer (BET). The pore size and pore volume have been analyzed by the BJH method to understand the adsorption mechanism. Reusability studies reveal that AIJLP could efficiently remove more than 95% of Pb(II) in up to five cycles. All these results recommend the AIJLP as a promising adsorbent for the remediation of Pb(II) from wastewater.