Properties of silica from rice husk and rice husk ash and their utilization for zeolite y synthesis

Abstract

Recebido em 21/12/10; aceito em 22/3/11; publicado na web em 10/6/11This study compared properties of silica (SiO 2 ) from rice husk (RH) and rice husk ash (RHA) extracted by acid-and heat-treatment. The SiO 2 from RH was in amorphous phase with nearly 100% purity while that from RHA was in crystalline phase with 97.56% purity. Both extracted SiO 2 were used in the synthesis of zeolite NaY but that from RH was better due to the efficiency in product recovery and simplicity of extraction. After the NaY was exchanged to NH 4 Y and calcined to convert to HY, the product did not carry over the textural properties of the parent NaY and NH 4 Y.

Characterization and application of biomass gasifier waste material for adsorptive removal of Cr (VI) from aqueous solution

“…The positive value of DS8 represents an increase in degree of freedom of the adsorbed species which indicates that some changes occur in the internal structure of adsorbent during the adsorption process. Generally DG8 values range from 0 to 220 kJ mol 21 for physical adsorption and 280 to 2400 kJ mol 21 for chemical adsorption [34]. In the present study, the DG8 value ranged from 28.13 to 216.63 kJ mol 21 indicating that adsorption of Cr (VI) on BGWM is mainly physical in nature.…”

“…Sharp peaks were noticed in XRD profile of both BGWM and BGWM‐Cr that confirms the crystalline nature of the adsorbent material. Sharp XRD peaks at 2θ values of 31.5° and 36.0° of BGWM and at 2θ values of 20.8°, 21.7°, and 26.6°, indicates silica in crystalline form . The highest intensity was found at 29.4° which indicates that carbon was the backbone of the BGWM.…”

“…(8) and (9), R is universal gas constant and T is temperature in Kelvin scale. To calculate the values of DS8 and DH8 a linear plot of ln (K c ) vs. 1/T ( Figure 10) was drawn on a temperature range of 25-408C at the initial Cr (VI) concentration of 10 mg L 21 . The values of these parameters are recorded in Table 3.…”

“…According to World Health Organisation (WHO) the permissible level for Cr (VI) in waste water is 0.05 mg L 21 [1]. For health significance Cr (VI) concentration must not be more than 0.05 mg L 21 .…”

Feasibility of Biomass Briquette Production from Municipal Waste Streams by Integrating the Informal Sector in the Philippines

“…Rice husks when burnt as fuel result in the oxidation of the carbonized ash to yield white ash that consists predominantly of silica [45]; a major inorganic component of rice husk, which is about 20 to 30 percent of its weight [46]. The inorganic materials present specifically for Briquette 3 may have produced the higher amount of percentage ash yield.…”