Zinc adsorption in bentonite clay: influence of pH and initial concentration

Abstract

ABSTRACT. This paper evaluated the adsorption capacity of zinc by Bofe bentonite clay. Bofe clay was subjected to a thermal treatment for optimizing its adsorption capacity. The kinetic equilibrium of the process was studied in a finite bath system and experiments were performed by varying pH, the amount of adsorbent and initial concentration of the metal. The Langmuir and Freundlich models were used for the analysis of adsorption equilibrium. The physicochemical characterization of clay, before and after the adsorption process, included the techniques of scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and N 2 physisorption. The calcined Bofe clay is able to remove zinc from synthetic wastewater. Langmuir model provided the best fit for sorption isotherms with a maximum amount of metal adsorbed of 4.95 mg of metal g -1 of calcined clay. The adsorption was strongly influenced by the initial conditions and modifies the physicochemical characteristics of the clay.Keywords: "Bofe", heavy metal, wastewater.Adsorção de zinco em argila bentonita: influência do pH, quantidade de adsorvente e concentração inicial RESUMO. Este trabalho teve como objetivo avaliar a capacidade de adsorção de zinco pela argila bentonítica Bofe. A argila Bofe foi submetida a um tratamento térmico para otimização de sua capacidade de adsorção. O equilíbrio cinético do processo foi estudado em um sistema de banho finito e experimentos foram realizados variando o pH, a quantidade de adsorvente e a concentração inicial de metal. Os modelos de Langmuir e Freundlich foram utilizados para a análise do equilíbrio de adsorção. A caracterização físico-química da argila, antes e após o processo de adsorção, envolveu as técnicas de microscopia eletrônica de varredura, espectroscopia de energia dispersiva de raios-X, difração de raios-X e fisissorção N 2 . A argila calcinada tem a capacidade de remover o zinco de efluentes sintéticos. O modelo de Langmuir forneceu o melhor ajuste para as isotermas de sorção com uma quantidade máxima de metal adsorvida de 4,95 mg de metal g -1 de argila calcinada. Verificou-se que a adsorção foi fortemente influenciada pelas condições iniciais do processo e a adsorção foi confirmada pelas modificações das características físico-químicas da argila.Palavras-chave: "Bofe", metal pesado, efluente.

Characterisation of Natural and HDTMA-Br Modified Dijah-Monkin Bentonite Clay: FTIR, XRF, XRD and SEM

“…The chemical analysis presented in Table 2 shows that the bentonite clays consist mainly of silica and alumina with metallic oxides such as Fe2O3, K2O, CaO, etc., present as minor. The most abundant components are Si and Al, which are the smectite clay group [5]. Generally, the Al2O3/SiO2 ratio obtained is 0.34 and 0.30 for natural and HDTMA-Br modified Dijah-Monkin clays, respectively, which is in close agreement with the expected value (i. e. 0.33) for montmorillonite [1].…”

Chromium and nickel metal ions removal from contaminated water using Nigerian bentonite clay

“…The elemental composition shows the presence of K and Ag in minor quantity while Ti and Mn are in trace amounts. The most abundant component of Si and Al in the sample confirmed the basic elements of the smectite clay group (Araujo et al 2013). The high iron content explained the brownish and reddish appearance of bentonite clay.…”

Silver sorption isotherms onto bentonites: Comparing mathematical models

“…This fact suggests that both bentonites can be applied in the sorption of metal ions as Ag + . Araujo et al studying a natural bentonite from Paraiba for Zn 2+ sorption found a PCZ of 6.0, while Kim found 8.0. However, a lower value for PCZ was found by Mekhamer studying a Saudi bentonite (PZC = 3.0).…”