Removal of hexavalent chromium by using red mud activated with cetyltrimethylammonium bromide

Abstract

The removal of hexavalent chromium [Cr(VI)] from aqueous solution by using red mud activated with cetyltrimethylammonium bromide (CTAB) was studied. The optimum operation parameters, such as CTAB concentration, pH values, contact time, and initial Cr(VI) concentration, were investigated. The best concentration of CTAB for modifying red mud was found to be 0.50% (mCTAB/VHCl,0.6 mol/L). The lower pH (<2) was found to be much more favourable for the removal of Cr(VI). Red mud activated with CTAB can greatly improve the removal ratio of Cr(VI) as high as four times than that of original red mud. Adsorption equilibrium was reached within 30 min under the initial Cr(VI) concentration of 100 mg L(-1). The isotherm data were analysed using Langmuir and Freundlich models. The adsorption of Cr(VI) on activated red mud fitted well to the Langmuir isotherm model, and the maximum adsorption capacity was estimated as 22.20 mg g(-1) (Cr/red mud). The adsorption process could be well described using the pseudo-second-order model. The result shows that activated red mud is a promising agent for low-cost water treatment.

Adsorption of Cr(VI) by material synthesized from red mud and rice husk ash

“…This might be explained by the fact that at concentrations greater than 15 g/l, aggregation of the material will occur, leading to a reduction of the adsorption surface. With a ZRM concentration of 10 g/l, the maximum Cr(VI) adsorption is 23.32 mg/g which is higher than that of RM modified cetyltrimethylammonium bromide (22.20 mg/g), as reported in the work of Li, et al [15].…”

“…This can be explained by the material surface being assembled H + and subsequently Cr(VI) being more easily adsorbed by the process of ion exchange. The reducing of absorption capacity when the pH is increased, might be because of the process of hydrolysis, which prevents the dispersion step in the adsorption process [15].…”

“…More than 200 million tons of RM will be wasted over 10 years, therefore, this amount rising to more than 1. 15 [8]. There has been much research focused on recycling and increasing the value of RM.…”

Production of electrolytic iron from red mud in alkaline media

“…Red muds can also be added at 5% to cement to produce building materials exhibiting the same mechanical properties as conventional cement (Vangelatos et al, 2009). Other works on red muds suggest using these residues as adsorbents for pollutants contained in wastewater, e.g., phosphate (Liu et al, 2007;Cusack et al, 2019), arsenic (Soner Altundoğan et al, 2000Mohan and Pittman, 2007;White et al, 2013;Rubinos and Spagnoli, 2019), chromium (Pradhan et al, 1999;Li et al, 2015), cadmium (Gupta and Sharma, 2002;Ju et al, 2012), and nickel (Zouboulis and Kydros, 1993).…”