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1.
Huan Jing Ke Xue ; 40(9): 4098-4104, 2019 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854873

RESUMO

Adsorption is an economical and effective method for recovering phosphate from wastewater. In order to improve the adsorption capacity of Fe3O4 for phosphate and for easy separation from water under the action of an external magnetic field, CaO2 was used in this study as an oxidant to partially oxidize Fe2+. A phosphorus recovery adsorbent, Ca doped Fe3O4 (CMIO), was prepared and was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and vibrating sample magnetometer (VSM) techniques. The results showed that CMIO had a Ca2+ doped Fe3O4 crystal structure with a saturation magnetization of 38.82 emu·g-1, which was easily separated from water by using an external magnetic field. The phosphorus adsorption capacity of the CMIO decreased with an increase of pH value. When pH=2 and T=25℃, the maximum adsorption capacity was 24.10 mg·g-1, which is almost five times the adsorption capacity of pure Fe3O4. The phosphorus adsorption of CMIO was in accord with the Langmuir isotherm adsorption model, and the adsorption process followed the pseudo-second order kinetic model. The complexation of phosphate occurred on the inner surface of the CMIO to form a ≡Fe-Ca-P ternary complex, which can adsorb phosphorus. Compared with other anions in the aqueous solution, CMIO had good adsorption selectivity to PO43-, and the adsorbed PO43- could be desorbed by NaOH solution.The quality loss of the CMIO was less than 4% once, and multiple recycling was possible.

2.
Huan Jing Ke Xue ; 38(3): 1151-1158, 2017 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965589

RESUMO

The evolution of sludge filteration dewaterability, floc structure and hydrolytic kinetics with calcium peroxide oxidation pre-treatment was investigated in this study. The effect of sludge characteristics with combined process of ferrous ion and calcium peroxide was deeply analyzed and the result suggested that the sludge dewatering performance was improved first and then worsened after CaO2 addition. When the dosage was 20 mg·g-1, sludge reached its optimal dewaterability. At the same time, sludge was effectively dissolved and the floc structure became loose and broken with the increase of organic matters in the supernatant. Moreover, sludge solubilization process followed the pseudo-zero-order kinetic equation well and the reaction rate of sludge with CaO2 treatment was 15.2 mg·L-1·h-1. In addition, sludge floc lysis was enhanced by the treatment of ferrous ion and calcium peroxide oxidation, whilst sludge dewaterability was improved due to the reconstruction of sludge floc structure by the iron ions produced. This study provided theoretical basis for application of calcium peroxide pre-treatment and its combining technique in sludge treatment.


Assuntos
Peróxidos/química , Esgotos , Eliminação de Resíduos Líquidos , Oxirredução
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