الفهرس 
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Abstract
In the present study alkali pretreatment of rice straw was applied in order to up grade it ( by lowering its silica content before entering the digester) such that the black liquor formed would be of acceptable silica content (maximum 1-2%SIO2 with respect to BL total solids) to be suitable for chemical recovery.
Such chemical recovery is not technically feasible at present in case of pulping of rice straw by conventional pulping method since the BL formed contains high silica content (10.7%SIO2 with respect to BL TS) . Different factors affecting silica reduction during the alkali pretreatment of rice straw were studied such as: % NaOH added (from 1 % to 8%), L/G ratio (19:1, 28:1), Temperature (70 c and 90 c), time (30-90min.), and also the effect of washing on silica reduction of NaOH
Pretreated rice straw. From the results it can be concluded that:
NAOH pretreatment of rice straw with 5% NaOH( With respect to O.D. Straw),L/G 19:1,70 C for 60min.With continuous stirring in a hydra pulper, followed by pressing without washing gave about 50%reduction in rice straw silica content(from 12.9% to 6.5%)wiyh actual reduction of 60.8% of SiO2input. A Further decrease of SiO2 to 3.68% is possible, but uneconomical-with increase of % NaOH to 8%