Environmental application of rice straw in energy production and potential adsorption of uranium and heavy metals |
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Authors: | Abram Farid Bishay |
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Institution: | (1) Nuclear Materials Authority, P.O. 530, El-Maadi-Kattamyia Road, Cairo, Egypt |
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Abstract: | The sustainable development of agricultural waste is nowadays a main strategy in producing neutral CO2 energy and metal removal technologies. In Egypt, large amounts of rice straw are annually burnt in the open air causing severe
air pollution that could be directed to co-firing and adsorption technologies. On bench scale, rice straw was positively contributed
in a clean and smokeless co-firing process with methanol due to the oxidizing effect of the alcohol. The co-firing temperature
control is vital to develop the adsorptive character of the residual ash and to avoid prolonged time needed to improve the
physical properties of the rice straw if applied directly as a biosorbent. The consumed methanol in the process ranges from
0.15 to 0.3 liter per each kg of straw depending on its compaction. The grossed heat value from such process may drive steam
generator for electricity. The residual ash was subsequently cross-linked in uranium and heavy metals adsorption tests from
solutions. The porous texture of the residual ash and the amorphous nature of the silica along with potassium content provide
a suitable condition for uranium immobilization especially if phosphorus or vanadium exist. The resulted chemical precipitate
is analogues in composition to meta-ankoleite (KUO2PO4·3H2O) or hydrated carnotite (K2(UO2)2V2O8)·1-3H2O respectively. The XRD data of the latter form show an enhancement in crystallinity of the amorphous precipitate with the
heated samples. |
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