Adsorptive Removal of Toxic Chromium from Waste-Water Using Wheat Straw and Eupatorium adenophorum.

Dagang Song,Zilong Li,Azizullah Azizullah,Akash Tariq,Feng Sun,Qinli Xiong,Kaiwen Pan,Amitava Mukherjee

doi:10.1371/journal.pone.0167037

Abstract

Environmental pollution with heavy metals is a serious issue worldwide posing threats to humans, animals and plants and to the stability of overall ecosystem. Chromium (Cr) is one of most hazardous heavy metals with a high carcinogenic and recalcitrant nature. Aim of the present study was to select low-cost biosorbent using wheat straw and Eupatorium adenophorum through simple carbonization process, capable of removing Cr (VI) efficiently from wastewater. From studied plants a low cost adsorbent was prepared for removing Cr (VI) from aqueous solution following very simple carbonization method excluding activation process. Several factors such as pH, contact time, sorbent dosage and temperature were investigated for attaining ideal condition. For analysis of adsorption equilibrium isotherm data, Langmuir, Freundlich and Temkin models were used while pseudo-first-order, pseudo-second-order, external diffusion and intra-particle diffusion models were used for the analysis of kinetic data. The obtained results revealed that 99.9% of Cr (VI) removal was observed in the solution with a pH of 1.0. Among all the tested models Langmuir model fitted more closely according to the data obtained. Increase in adsorption capacity was observed with increasing temperature revealing endothermic nature of Cr (VI). The maximum Cr (VI) adsorption potential of E. adenophorum and wheat straw was 89.22 mg per 1 gram adsorbent at 308K. Kinetic data of absorption precisely followed pseudo-second-order model. Present study revealed highest potential of E. adenophorum and wheat straw for producing low cost adsorbent and to remove Cr (VI) from contaminated water.

Highlights

Heavy metals contamination is a growing issue affecting living organisms throughout the world [1,2]
Chromium (Cr) is a harmful heavy metal and exists in various oxidative forms; the trivalent and hexavalent states are considered more essential in term of environmental pollution point of view [4]
The aim of the present study is to design an adsorbent of low cost wheat straw and E. adenophorum through simple carbonization process, which can efficiently absorb and remove Cr (VI) from wastewater

Summary

Introduction

Heavy metals contamination is a growing issue affecting living organisms throughout the world [1,2]. Due to rapid industrial development, direct and indirect discharges of heavy metals to the environment through wastewater have tremendously been increased [2]. Chromium (Cr) is a harmful heavy metal and exists in various oxidative forms; the trivalent and hexavalent states are considered more essential in term of environmental pollution point of view [4]. There are varied Cr contamination sources such as electroplating, leather tanning, textile industries, metal finishing, nuclear power plants, and chromate preparation [6]. Concentration of Cr (VI) is severely restricted and as per Environmental Protection Agency (EPA) guidelines the maximum permitted limit for Cr (VI) in inland surface, potable and industrial wastewaters are 0.1, 0.05, and 0.25 mg L−1, respectively. There is a dire need of significant management of wastewater contaminated by Cr (VI) before its release

Objectives

Methods

Conclusion