Abstract
This study investigated the heat-acid activated red mud used for hexavalent chromium (Cr6＋) removal from aqueous solution. The results showed that the heat-acid activated red mud enhanced hexavalent chromium removal capacity from 0.003 to 0.015 mg·g﹣1. Adsorption experiments were conducted as a function of adsorbent dosage, contact time, pH and reaction temperature. The removal efficiency was found to increase gradually when solution pH decreased and maximum removal was achieved at pH 2. The physico-chemical characteristics of heat-acid activated red mud were studied by using instrumental technique like Scanning Electron Microscope (SEM), X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF). The experimental data fitted well to Langmuir isotherm model. Thermodynamic parameters indicated the adsorption process was exothermic reaction. The cost-effective performance and, simple operation suggest the heat-acid activated red mud can be taken as a promising sorbents for removal of Cr6＋ from wastewater.
Highlights
Hexavalent chromium is one of the heavy mental contaminants found in the water which is used in a variety of applications including electroplating, steel production, leather tanning, mining and textile dyeing [1]
The present work shows that thermally activated acid neutralized red mud can be used as adsorbent for the removal of hexavalent chromium from aqueous solutions successfully
The X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF) studies revealed that Red mud (RM) contains significantly more metal ions than acidified red mud (ARM)
Summary
Hexavalent chromium is one of the heavy mental contaminants found in the water which is used in a variety of applications including electroplating, steel production, leather tanning, mining and textile dyeing [1]. Chromium usually exists in both trivalent and hexavalent forms in water, and trivalent chromium is an essential trace element for human and plays a vital role in normal carbohydrate, lipid and protein metabolism [2]. How to cite this paper: Ma, M., et al (2014) Hexavalent Chromium Removal from Water Using Heat-Acid Activated Red Mud. Open Journal of Applied Sciences, 4, 275-284. A variety of materials have used as hexavalent chromium sorbents, including activated carbon, zeolite, bentonite, biological materials, fly ash, red mud and others [11]-[16]. In the present work an attempt has been made to use the acidified red mud (ARM) as an adsorbent for the removal of hexavalent chromium from model aqueous solution, to investigate the effect of contact time, initial solution pH and temperature on the adsorption, and to discuss the adsorption isotherm of ARM for hexavalent chromium
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