Adsorption of Cr(VI) in Aqueous Solution Using a Surfactant-Modified Bentonite

Abstract

Clay minerals can be modified organically by a cationic surfactant resulting in materials known as organoclays. The organoclays have been used as adsorbents of most of the organic contaminants in the aqueous solution and oxyanions of the heavy metal. In this study, a Colombian bentonite was modified with hexadecyltrimethylammonium bromide to obtain an organobentonite, and its capacity to adsorb Cr(VI) oxyanions in the aqueous solution was evaluated. The effect of pH, stirring speed, adsorbent amount, contact time, and ionic strength were investigated at 25°C. Stirring speeds above 200 rpm, contact times greater than 120 min, and the addition of NaCl (0.1 to 2.0 mM) did not have a significant effect on Cr(VI) removal. The influence of the adsorbent amount and pH on Cr(VI) adsorption was studied by the response surface methodology (RSM) approach based on a complete factorial design 32. Results proved that the Cr(VI) adsorption follows a quadratic model with high values of coefficient of determination (R2 = 95.1% and adjusted R2 = 93.9%). The optimal conditions for removal of Cr(VI) from an aqueous solution of 50 mg/L were pH of 3.4 and 0.44 g amount of the adsorbent. The adsorption isotherm data were fitted to the Langmuir and Freundlich adsorption isotherm models, and the model parameters were evaluated. The maximum adsorption capacity of Cr(VI) onto organobentonite calculated from the Langmuir model equation was 10.04 ± 0.34 mg/g at 25°C. The results suggest that organobentonite is an effective adsorbent for Cr(VI) removal, with the advantage of being a low-cost material.

Catalytic Oxidation of Ponceau 4R in Aqueous Solution using Iron-impregnated Al-pillared Bentonite: Optimization of the Process

“…coefficients, respectively; Xi and Xj are the coded levels for independent variables, and k = 3, i.e., the number of independent variables. The quality of the model fits was evaluated by the coefficients of determination (R 2 and adjusted R 2 ) and analysis of variance (ANOVA) [59,60]. Analysis of variance (ANOVA) was applied for estimating the model significance.…”

Fixed-Bed Modification of Zeolitic Tuffs and Their Application for Cr(VI) Removal

“…In turn, the C-H symmetric stretching vibration preserves an unchanged position. The band at 1460 cm −1 is associated with N-CH 3 stretching of the cationic surfactant [29].…”

Soft Ion Divalent Metals toward Adsorption on Zn/Al-POM Layered Double Hydroxide

“…In the environment, heavy metals have a low toxicity level of around 1.0-10.0 mg/L, Therefore, reducing the heavy metal levels from wastewater in the environment has become a major, serious matter, and an urgent task [Chakraborty et al, 2020]. Tchounwou et al, [2012] reported that metals such as cobalt (Co), lead (Pb), cadmium (Cd), and nickel (Ni) have a non-biological functions in Soft Ion Divalent Metals toward Adsorption on Zn/Al-POM Layered Double Hydroxide Luna Silaen 1 , Elfita 2 , Risfidian Mohadi 3 , Normah 4 , Novie Juleanti 4 , Neza Rahayu Palapa 4 , Aldes Lesbani 1,4* the body and are considered non-essential metals. Thus, metal ions are stable and if they enter the body, they cannot be metabolized [Taiwo and Chinyere, 2016].…”

“…Researchers have carried out decontamination of the environmental water contaminated by heavy metals using such methods as chemical precipitation, filtration, electrochemistry, coagulation-flocculation, oxidation, ion exchange, and adsorption [Cocheci et al, 2010;Ali et al, 2012;Mohamed et al, 2019;Castro-Castro et al, 2020;Normah et al, 2021] The adsorption method is preferred due to its simplicity, low cost, the ease of operation , the flexibility of the design and the choice of adsorbent, as well as environmental friendliness [Oktriyanti et al, 2019;Forghani et al, 2020;Silaen et al, 2020]. On the basis of various works of literature, different types of adsorbents have been applied to reduce the levels of heavy metals contained in wastewater, including the adsorbents that have porous or layered characteristics, such as bentonite, activated carbon, kaolin, and layered double hydroxides (LDHs) [Wahab et al, 2019;Chai et al, 2020;Zhang et al, 2020a].…”