Effect of deashing rice straws on their derived activated carbons produced by phosphoric acid activation

We studied the effect of physically and/or chemically deashing rice straw (RS) on the adsorption capacity of their derived activated carbons (ACs) produced by chemical activation with H3PO4. Surface area and pore volumes were determined by nitrogen adsorption at 77 K. Methylene blue adsorption isotherms onto ACs were carried out, and we applied Langmuir and Freundlich models to fit the adsorption data. We showed that preliminary deashing does not bring significant improvement to the resultant ACs’ properties. ACs prepared by H3PO4 activation of raw and deashed RS have intermediate performances between those of ACs prepared by 1- and 2-step KOH activation, but are much cheaper to produce.