Adsorption Behavior of Cd2+ and Zn2+ onto Natural Egyptian Bentonitic Clay

Nagwa Burham,Mahmoud Sayed

doi:10.3390/min6040129

Abstract

In the present work, an Egyptian bentonitic clay sample has been structurally characterized using different techniques such as XRD, IR, SEM, and EDX analyses then evaluated as a sorbent for heavy metal ions removal. The characterization results showed that the clay sample is in the bentonite form with montmorillonite and kaolinite as mixed-clay minerals. The specific surface area (SSA) and cation exchange capacity (CEC) were determined using methylene blue test and they were found to be 367 m2/g and of 85 meq/100 g, respectively. The applicability of this clay sample for Cd (II) and Zn (II) removal from aqueous media was tested using batch procedures. Experimental parameters affecting the removal process were analyzed to get optimum conditions for the process. The experimental kinetic data were fitted very well to pseudo-second order with very high correlation coefficients. The Freundlich model appeared to correlate the adsorption data much better than Langmuir model with maximum adsorption capacities of 8.2 and 9.45 mg/g for Cd2+ and Zn2+, respectively. Successful application of the studied adsorbent for the removal of Cd2+ and Zn2+ ions from natural water samples greatly supports its potential for practical application.

Highlights

An enormous amount of toxic heavy metals is being discharged into the environment as a waste product from batteries, tanneries, electroplating, pesticides, fertilizers, mining and ore refining industries [1]
The results of the physicochemical characterizations have shown that the studied clay sample is bentonite with interstratified montmorillonite-kaolinite clay fraction with 85 meq/100 g Cation Exchange Capacity (CEC) and
It was found that the adsorption of Cd (II) and Zn (II) to Na–B is greatly influenced by the solution pH, contact time, sorbent dose, and initial metal ions concentration

Summary

Introduction

An enormous amount of toxic heavy metals is being discharged into the environment as a waste product from batteries, tanneries, electroplating, pesticides, fertilizers, mining and ore refining industries [1]. Heavy metals tend to accumulate in bio-organisms resulting in potential risks to human and environmental health [2]. Cadmium and zinc have attracted great attention due to their hazardous nature. It can cause kidney damage and renal disorder, while zinc may result in depression, lethargy, neurological symptoms and retardation of children’s growth [3].

Methods

Results

Conclusion