Chromium Biosorption from Cr(VI) Aqueous Solutions by Cupressus lusitanica Bark: Kinetics, Equilibrium and Thermodynamic Studies.

Alma Rosa Netzahuatl-Muñoz,María Del Carmen Cristiani-Urbina,Eliseo Cristiani-Urbina,Heidar-Ali Tajmir-Riahi

doi:10.1371/journal.pone.0137086

Alma Rosa Netzahuatl-Muñoz, María Del Carmen Cristiani-Urbina + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0137086

Copy DOI

Abstract

The present study investigated the kinetics, equilibrium and thermodynamics of chromium (Cr) ion biosorption from Cr(VI) aqueous solutions by Cupressus lusitanica bark (CLB). CLB total Cr biosorption capacity strongly depended on operating variables such as initial Cr(VI) concentration and contact time: as these variables rose, total Cr biosorption capacity increased significantly. Total Cr biosorption rate also increased with rising solution temperature. The pseudo-second-order model described the total Cr biosorption kinetic data best. Langmuir´s model fitted the experimental equilibrium biosorption data of total Cr best and predicted a maximum total Cr biosorption capacity of 305.4 mg g-1. Total Cr biosorption by CLB is an endothermic and non-spontaneous process as indicated by the thermodynamic parameters. Results from the present kinetic, equilibrium and thermodynamic studies suggest that CLB biosorbs Cr ions from Cr(VI) aqueous solutions predominantly by a chemical sorption phenomenon. Low cost, availability, renewable nature, and effective total Cr biosorption make CLB a highly attractive and efficient method to remediate Cr(VI)-contaminated water and wastewater.

Highlights

Environmental chromium (Cr) contamination has become a public health issue because industrial Cr emissions have heavily polluted sites even in close vicinity to residential areas [1]
Scanning electron microscopy (SEM) micrographs reveal that Cupressus lusitanica bark (CLB) has a rough and porous surface texture, with irregular pores that have a diameter exceeding 50 nm, which indicates that CLB has a macroporous structure (Fig 1)
The potential of CLB to biosorb total Cr from Cr(VI) aqueous solutions was explored in the present work

Summary

Introduction

Environmental chromium (Cr) contamination has become a public health issue because industrial Cr emissions have heavily polluted sites even in close vicinity to residential areas [1]. Among the major Cr pollution sources of aquatic ecosystems are the electroplating and metal finishing industries, iron and steel foundries, the inorganic chemical plants and tanneries [2,3]. Cr contamination has been considered as one of the most serious environmental problems in the last few decades [4]. Cr is considered a priority pollutant in many countries [5].

Objectives

Methods

Results

Conclusion