Synthesis and characterization of Fe-MCM-41 from rice husk silica by hydrothermal technique for arsenate adsorption

Abstract

Rice husk (RH) agro-waste was used as a raw material for synthesizing mesoporous molecular sieves, MCM-41. The Fe-MCM-41 was prepared by the hydrothermal technique (HT), resulting in a higher surface area and crystallinity than when prepared under ambient conditions. In addition, a hexagonal structure was clearly seen with hydrothermal technique (HT) preparation. The adsorption of arsenate by HT-Fe-MCM-41 was investigated. The factors studied affecting arsenate adsorption capacity were ferric content in MCM-41, contact time, pH of solution, and initial arsenate concentration. It was found that HT-Fe-MCM-41 at the Si/Fe mole ratio of 10 gave the highest adsorption capacity. Arsenate adsorption reached equilibrium within 4 h. The adsorption capacity of HT-Fe-MCM-41 (Si/Fe = 10) was affected by the initial pH value and the initial arsenate concentration. The adsorption capacity was highest at pH 3 and decreased thereafter with increases in the pH of solution value. The Langmuir model fit the arsenate adsorption isotherm well. The maximum adsorption capacity for arsenate was 1,111 microg g(-1).

Optimal Decolorization Efficiency of Reactive Red 3 by Fe-RH-MCM-41 Catalytic Wet Oxidation Coupled with Box-Behnken Design

“…The Fe-RH-MCM-41 was prepared according to our previous work [8] excepted for Fe source from Fe(NO 3 ) 3 .9H 2 O as following, (i) 4.50 g of hexadecyltrimethyl ammonium bromide (CTAB) and Fe precursor were mixed with 90 ml of deionized water in a Teflon beaker, (ii) sodium silicate was prepared in another Teflon container by dissolving 5.00 g of NaOH in 30 ml of deionized water, then, 3.00 g of rice husk silica was added as resulted at Si/Fe mole ratio of 10. Next, the solution was stirred vigorously until it was clear and viscous.…”

Removal of Arsenic from Aqueous Solution by Fe(III)- Impregnated Sorbent Prepared from Sugarcane Bagasse

“…Effect of pH was studied by adjusting the initial pH of arsenic solutions using diluted HNO3 and NaOH solutions (pH = 2, 3,4,5,6,7,8,9,10,11,12) and the solutions were agitated with 0.3 g/50 mL sorbent for 2 mg/L arsenic concentrations at 25 ºC. Eleven initial concentrations for arsenic (1,2,4,6,8,10,12,14,16,18 and 20 mg/L) were employed for the study of initial concentration effect on sorption at 25, 35 or 45 ºC.…”

“…If low cost alternative sorbents can be developed, it would be beneficial to the environment and have attractive commercial value. In these aspects, various materials such as activated sludge, iron oxide, granular ferric hydroxide, rice hush silica and red mud have been investigated for arsenic sorption [7][8][9][10][11][12] .…”