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Palm shell-based adsorbents prepared under five different thermochemical conditions and palm shell powder have been shown to be quite effective for removal of uranium from aqueous solutions. X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and Fourier transform infrared spectroscopy (FTIR) have been used to determine information about the speciation and binding of uranium on the adsorbents under study. Studies indicate that the uranium which is present as uranyl ion in aqueous solution is present in mixed valence states (U(IV), U(V), and U(VI)) when it is bound to the adsorbents. The mechanism of adsorption is likely to be adsorption-coupled reduction as well as complexation. Adsorption of uranium, cesium, and iron was found to be quantitative in binary as well as ternary mixtures.

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The adsorption of reactive dyes onto acid-treated palm shell powder (APSP) and chitosan has been investigated. The parameters affecting the rate process involved in the removal of dye like contact time, temperature, pH, adsorbent dose, and dye concentration were studied. pH 4 was suitable for the adsorption of both reactive dyes onto chitosan and was independent of pH in the range pH 2 to 9 using APSP as the adsorbent. The process of dye removal followed pseudosecond-order kinetics. The adsorption equilibria isotherms were analyzed by the Langmuir and Freundlich isotherms. The adsorption capacities were found to be 13.95 mg • g -1 and 24.86 mg • g -1 for reactive red 141 and reactive blue 21 using APSP as adsorbent. The adsorption capacities were found to be 22.48 mg • g -1 and 70.08 mg • g -1 for reactive red and reactive blue, respectively, using chitosan as the adsorbent.

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