Background: Agricultural wastes are widely applied in heavy metal wastewater treatment

and became a hot point in this field. Purpose: The aim is to study modified rice straw with significant removal ability of thorium. Methods: The rice straw modified with butanedioic acid was used to remove Th4+ from aqueous solution. And its influence factors such as adsorbent dosage

pH

adsorption time and reaction temperature were investigated through dynamic tests. Results: The optimal conditions were found to be 0.50 g of modified rice straw

pH=3.5

0.5 h of adsorption time and 10 mg?L?1 of initial thorium concentration at 65 oC. Under these conditions

the removal rates reach 96%. Fourier transform infrared spectroscopy (FTIR) analysis shows some new adsorption peaks such as carboxyl

ester and hydroxyl has added to modified rice straw. The adsorption behavior of Th4+ could be fitted well by the Freundlich adsorption isotherms and the quasi-second order kinetics equation. Conclusion: Its absorptive property enhancement might attribute to expose more internal porous structure of lignin and cellulose and add special functional groups by the modifying process.Cited