Application of a compound containing silica for removing ammonium in aqueous media

Abstract

In the present investigation, removal of ammonium from aqueous solutions by a compound containing silica was considered. The compound was a waste of ferrosilicon compound produced during Ferro-alloy manufacturing. The results showed that an increase in the pH of solution up to 7 caused a rapid increase in the adsorbed ammonium to 36.21 mg/g. But adsorbed ammonium was decreased to 26.51 mg/g as the initial pH reached to 10. The amount of adsorbed ammonium was increased with contact time and initial ammonium concentration. A contact time of 180 min was selected because there was no significant increment in adsorbed ammonium as contact time was further increased. The results exhibited suitability of the pseudo-second order kinetic model (R 2 5 0.9867). Increasing initial ammonium concentration from 10 to 180 mg/L resulted in an increment in adsorbed ammonium from 6.69 to 59.13 mg/g, respectively. The obtained data were fitted to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models in which the obtained correlation coefficient showed the relatively better fitness of the data to Langmuir model (R 2 5 0.9969) with a maximum adsorption capacity of 78.74 mg/g.

Optimization of the adsorption of a textile dye onto nanoclay using a central composite design

“…31 The presence of various binding groups on the surface of adsorbent, especially ionizable -OH groups, would be beneficial for the adsorption of cationic species such as BY2. 28 It can be observed that the intensity of the peak associated with the -OH group diminished after the adsorption of BY2, which confirmed the significant role of this peak in the adsorption process. Compared to MMT, the spectra of dye-loaded clay showed two additional peaks at 1418…”

Application of Nanocrystalline Iranian Diatomite in Immobilized Form for Removal of a Textile Dye

“…Moreover, the peak placed at 480 cm -1 reflects Si-O-Si bending vibration [29,34]. The diatomite structure consists of siloxane groups or -Si-O-Si-bridges with oxygen atoms that can act as an adsorptive site for the adsorption of target pollutants [26].As shown in of hydroxyl groups and free silanol group (Si-OH) in the adsorption process.…”

“…wherek 2ads (g/mg.min)is the pseudo-second order reaction rate constant [20,29]. The intra- where q t (mg/g), k p (mg/g.min 0.5 ) and Care the amount of adsorbed dye at time t, the rate constant and intercept of the plot, respectively [23].…”

“…where R and T are universal gas constant (8.314 J/mol K) and absolute temperature (K), respectively [22,29].The obtained data were processed and the results of isotherm study were provided in Table 1. As given, among different isotherm models, the Langmuir isotherm model best fits the experimental data due to the highest value of coefficient of determination (R 2 = 0.9732).…”

“…It contains many silanol groups, which have a tendency to adsorb organic compounds. Moreover, diatomite has low density, high permeability (0.1-10 mD), high porosity (25-65%) and subsequently high surface area creating a suitable structure for the adsorption of target pollutants [20,22,24,26,27].Silica-based adsorbents such as diatomite have already been used for the adsorption of inorganic and organic pollutants in raw and modified form [20,[27][28][29]. However, in the present study, the application of nano-crystalline Iranian diatomite prepared through ball milling technique was applied for the adsorption of an azo dye (Direct Red23 (DR23)) in aqueous solution.…”