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Journal of Wuhan University of Technology-Mater. Sci. Ed. Oct.2012 931
DOI 10.1007/s11595-012-0576-2
Adsorption of Congo Red onto Lignocellulose/ Montmorillonite Nanocomposite
ZHAO Yahong1, XUE Zhenhua1, WANG Ximing1, WANG Li1, WANG Aiqin2
(1.College of Material Science and Art Design, Inner Mongolia Agricultural University, Hohhot 010018, China; 2. Center of Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China)
Abstract: Lignocellulose/montmorillonite (LNC/MMT) nanocomposites were prepared and characterized by FTIR and XRD. The adsorption of congo red (CR) on LNC/MMT nanocomposite was studied in detail. The effects of contact temperature, pH value of the dye solutions, contact time and concentration of dye solutions on the adsorption capacities of lignocellulose (LNC), montmorillonite (MMT) and the nanocomposite were investigated. The adsorption kinetics and isotherms and adsorption thermodynamics of the nanocomposite for CR were also studied. The results show that the adsorption capacity of LNC/MMT nanocomosite is higher than that of LNC and MMT. All the adsorption processes t very well with the pseudo-second-order and the Langmuir equation. From thermodynamic studies, it is seen that the adsorption is spontaneous and endothermic.
Key words: lignocellulose; montmorillonite; nanocomposite; adsorption; congo red
1 Introduction
The presence of dyes in effluents is a major concern due to their adverse effect to many forms of life. The discharge of dyes in the environment is worrying for both toxicological and esthetical reasons[1]. Industries including textile, leather, paper and plastics are some of the sources for dye efuents[2].
Many reactive dyes are toxic to some organisms and hence harmful to aquatic animals[3]. Furthermore, some dyes and their reaction products, such as aromatic amines, possess high carcinogenicity. Besides, they also pose a problem because they may be mutagenic and carcinogenic and can cause severe damage to human beings, such as dysfunction of kidney, reproductive system, liver, brain and central nervous system[4, 5]. In
addition, due to its high water-solubility, it is estimated that 10-20% of reactive dye remains in wastewater during production and nearly 50% of reactive dyes
may be lost to the efuents during dyeing process[6, 7].
Various treatment technologies have been used for the remove of dyes from the effluents, such as chemical coagulation-flocculation[8], oxidation[9], biological process[10], membrane-based separation processes[11-13]. All of the above processes have their own benefits and limitations....