Chemically Modified Rice Husk Adsorbents, Characterization and Removal of Palladium(II) From Aqueous Solutions

Rice husk (RH) was chemically modified to prepare different adsorbents for the removal of Pd(II) from aqueous solutions. Succinylated rice husk (RHS) was prepared by treating RH with succinic anhydride to introduce carboxylic functions to rice husk. RHS was used to anchor various polyamines, viz., ethylenediamine (ED) and diethylenetriamine (DT), to prepare new adsorbents, abbreviated as RHS-ED and RHS-DT, respectively. All these adsorbents were characterized by elemental analysis, PSD, FTIR, XRD, and SEM. The selectivity order for Pd(II) removal was found to be: RHS-DT>RHS-ED>RH>RHS. The Freundlich isotherm was found to fit adsorption data well for all the adsorbents under study. The monolayer adsorption capacities of for RH, RHS, RHS-ED, and RHS-DT obtained from Langmuir isotherm are 11.57, 7.710, 13.73, and 15.72mg/g, respectively. The adsorption kinetic data were fitted well with pseudo-second-order kinetics model.