Study Of Adsorption Performance Of Pollutants Onto Ceramsite Adsorbents Based On Different Solid Wastes

The production of waste solids in China annualy is massive,which includes industry byproducts and riverbed sediments.With the expansion of the industry development,the amount of the produced by-products increased exponentially.Meanwhile,the sediments of many rivers have been dredged due to long-time contamination from the heavy metals present in the river,this causes a large volume of sediments which need to be treated.In total,the waste solids like industry by-products and riverbed sediments will compromise the ecological safety if not treated and disposed appropriately.The micro-polluted situation in rivers is quite normal in China,the traditional treatment technologies can not be implemented due to the the pollution level is relatively low and the volume of the water bodies is enormous.The continuous existence of the pollutants will keep threatening the safety of the nature water bodies.Adsorption technology is an applicable technology for micro-polluted water bodies because of its high operability,low cost and little ecotoxicity.This study based on the use of solid wastes ceramsite adsorbent preparation.Least toxic,eco-friendly adsorbent was prepared,and the adsorption behavior of arsenate and phosphate present in aqueous system was studied.(1)Different temperatures have a great influence on the morphology of arsenic in the ceramsite prepared from arsenic-containing riverbed sediment.With the increase of temperature,the arsenic present in residual form in the ceramsite gradually decreases and changes to a more active form of arsenic.But keep rising the temperature will eventually lead to an increase of residual arsenic,which accounts for 74.05% of the total arsenic content at 1200 ?.According to the leaching of arsenic from the ceramsite at different time intervals,we can find that the iron,aluminum and other metal elements in the raw materials re-adsorb the arsenic during the leaching process.Therefore,the maximum leaching value within a fixed time should be considered when determining the leaching capacity of solid wastes rather than the final leaching value.(2)The ceramsite prepared with arsenic-contained riverbed sediment was impregnated with iron to form a iron-loaded adsorbent.Under the ambient temperature of 25 ?,the adsorbent dosage of 1 g/L,the p H value of 7,and the reaction time was 120 min,the maximum saturated adsorption amount reached 10.64 mg/g.The adsorption process was endothermic.The adsorption process conforms to pseudo-second-order kinetic and Freundlich isotherm model.The phosphate in the solution has a great influence on the adsorption of arsenic by the adsorbent because it can form a stable inner sphere complex with the hydroxyl group on the adsorbent surface like arsenate,therefore,it has a great influence on the adsorption of arsenic.The addition of a certain amount of adsorbent in actual sediment leaching has a good adsorption effect on controlling the arsenic leaching of sediment.(3)The response surface method was used to optimize the preparation condition of ceramsite from different solid wastes.It was found that with the increase of sintering temperature,the metal in ceramsite was activated which leads to the increased of toxic leaching.When the amount of red mud in raw materials was increased,the toxic leaching of ceramsite decreased significantly.It can be considered that iron and aluminum present in red mud had an effect that can fixed the heavy metals in ceramsite,while the sintering time had no significant effect on the toxic leaching.(4)The adsorption capacity of phosphate in water was studied by using ceramsite adsorbent prepared by different solid wastes.The results showed that the adsorbent had a good adsorption performance of phosphate in aqueous system,and the adsorption equilibrium time was only 10 min,the adsorption was an endothermic reaction.At the ambient temperature of 25 ?,the adsorbent dosage of 1 g/L,and the p H value of 7,the adsorption capacity of adsorbent reached 9.84 mg/g.The adsorption process was in accordance with the pseudosecond-order kinetics and the Langmuir isothermal model.The co-existing anions and p H had an insignificant effect on the adsorption process,the adsorption from real wastewater also achieved a great result.