Efficient Removal of Cd(II) Using SiO2-Mg(OH)2 Nanocomposites Derived from Sepiolite

Abstract

The pollution of Cadmium (Cd) species in natural water has attracted more and more attention due to its high cumulative toxicity. In the search for improved removal of cadmium from contaminated water, we characterized uptake on a recently identified nanomaterial (SiO2-Mg(OH)2) obtained by subjecting sepiolite to acid-base modification. The structural characteristics of SiO2-Mg(OH)2 were analyzed by means of SEM-EDS, Fourier Transform Infra-Red Spectroscopy (FTIR) and Powder X-ray Diffraction (PXRD). Static adsorption experiments were carried out to evaluate the effect of contact time, temperature, amount of adsorbent, and pH-value on the adsorption of Cd(II) by SiO2-Mg(OH)2. The results show that the pore structure of SiO2-Mg(OH)2 is well developed, with specific surface area, pore size and pore volume increased by 60.09%, 16.76%, and 43.59%, respectively, compared to natural sepiolite. After modification, the sepiolite substrate adsorbs Cd(II) following pseudo-second-order kinetics and a Langmuir surface adsorption model, suggesting both chemical and physical adsorption. At 298 K, the maximum saturated adsorption capacity fitted by Sips model of SiO2-Mg(OH)2 regarding Cd(II) is 121.23 mg/g. The results show that SiO2-Mg(OH)2 nanocomposite has efficient adsorption performance, which is expected to be a remediation agent for heavy metal cadmium polluted wastewater.

Uses of Nanoclays and Adsorbents for Dye Recovery: A Textile Industry Review

“…However, it does not offer good adsorption results with azo acid dyes [238]. One study employed SiO 2 -Mg(OH) 2 derived from sepiolite to remove the Cd(II) present in dye with up to 95% adsorption [239]. It worked considerably better at a neutral pH than at a basic pH, and at constant temperature (T = 25 • C) [240].…”

New Efficient Adsorbent Materials for the Removal of Cd(II) from Aqueous Solutions

“…This behavior can be explained by the surface loading of the adsorbent material and by the competitive adsorption of protons [17,32]. At lower pH values the adsorbent surface is positively charged and therefore there is an electrostatic repulsion between the adsorbent surface and cadmium cations [33,34]. In the same time at higher pH values, Cd ions could precipitate under Cd(OH) 2 and then the adsorption is inhbitated [33,35,36].…”

“…At lower pH values the adsorbent surface is positively charged and therefore there is an electrostatic repulsion between the adsorbent surface and cadmium cations [33,34]. In the same time at higher pH values, Cd ions could precipitate under Cd(OH) 2 and then the adsorption is inhbitated [33,35,36]. Further experiments were carried out with Cd(II) solution having an initial pH of 5.…”

Effectiveness and Characterization of Novel Mineral Clay in Cd2+ Adsorption Process: Linear and Non-Linear Isotherm Regression Analysis

“…Adsorption often has advantages over other processes due to its low start-up and installation costs, high selectivity, practicality, flexibility, ease of operation, low environmental risk, resistance to toxic components and significant potential for the removal of hazardous, unsafe contaminants [33,34]. Up until now, different materials have been used for the removal of Cd 2+ , such as brewery yeast [35], barley husks [36], brewed tea waste [33], nanocomposites [37,38], eggshell [39,40], Adsorption technology is a widely accepted method because it is both simple to use and effective even at low concentrations [32]. Adsorption often has advantages over other processes due to its low start-up and installation costs, high selectivity, practicality, flexibility, ease of operation, low environmental risk, resistance to toxic components and significant potential for the removal of hazardous, unsafe contaminants [33,34].…”

“…Adsorption often has advantages over other processes due to its low start-up and installation costs, high selectivity, practicality, flexibility, ease of operation, low environmental risk, resistance to toxic components and significant potential for the removal of hazardous, unsafe contaminants [33,34]. Up until now, different materials have been used for the removal of Cd 2+ , such as brewery yeast [35], barley husks [36], brewed tea waste [33], nanocomposites [37,38], eggshell [39,40], sunflower [41], peanut shell [42], sugarcane bagasse [43], different clay materials [44][45][46][47][48][49], and minerals like montmorillonite, kaolinite, illite, zeolite, diatomite, vermiculite [50].…”