Removal of Pb(II) Ions from Aqueous Solution Using Modified Starch

O H P Gunawardene,W A Manamperi,N M L Fernando,P N K Fernando,C A Gunathilake,K M A K Kulatunga,J A S C Jayasinghe,A Gamage,A P S M Amaraweera,B G N D Weerasekara,A Manipura,R S Dassanayake,S M Rajapaksha,C A N Fernando

doi:10.3390/jcs5020046

Abstract

In this study, two types of modified cassava starch samples (MCS and MWS) prepared from commercially available native cassava starch (NCS) and native cassava starch extracted using the wet method (NWS) were investigated for the removal of Pb(II) ions from aqueous solutions. MCS and MWS samples were synthesized under acidic conditions using Pluronic 123 as the structure-directing agent and tetraethylorthosilicate (TEOS) as the chemical modifying agent. Modified starch samples were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray Diffraction (XRD), and a nitrogen (N2) gas adsorption–desorption analyser. MCS and MWS showed enhanced thermal stabilities upon acid hydrolysis and chemical modification. The effects of contact time and initial Pb(II) concentration were studied through batch adsorption experiments. Adsorption kinetics followed the pseudo-second-order kinetic model. The equilibrium adsorption data were analysed and compared by the Langmuir and Freundlich adsorption models. The coefficient correlation (R2) was employed as a measure of the fit. The Langmuir model fitted well with equilibrium adsorption data, giving a maximum Pb(II) adsorption capacity of 370.37 and 294.12 mg/g for MWS and MCS, respectively. Modified samples exhibited a higher desorption efficiency of over 97%. This study demonstrated that modified starch could be utilized for Pb(II) removal from industrial wastewater.

Highlights

With the rapid industrialization and urban development across the globe, excessive release of heavy metals into the environment has significantly affected soil, plants, aquatic life, animals, and humans [1,2,3,4]
We report the removal of Pb(II) ions from an aqueous solution using two types of modified starch samples prepared from commercially available cassava starch and native cassava starch extracted in the lab
The structure-directing agent, Pluronic 123, is a block-copolymer containing hydrophilic ethylene oxide (EO) and hydrophobic propylene oxide (PO) parts. Both starch and TEOS are hydrolyzed under acidic conditions; see Scheme 1

Summary

Introduction

With the rapid industrialization and urban development across the globe, excessive release of heavy metals into the environment has significantly affected soil, plants, aquatic life, animals, and humans [1,2,3,4]. Heavy metals can be added into the environment through natural processes, including weathering, erosion, and volcanic actions [3,4,7,9,12]. Once released into the environment, heavy metals affect ecological life through bioaccumulation and biomagnification [3,16]. Heavy metal toxicity can be either acute or chronic [7]. Chronic long-term exposure to heavy metals can lead to cancer or even death [17,18,19,20,21,22]

Methods

Results

Conclusion