Synthesis A Ce-Mn Binary Oxide Via Hydrothermal Method And Its Antimony Removal Performance And Mechanism

Antimony is an element similar to arsenic,which has chronic toxicity and carcinogenicity to organisms.Continuous exposure to antimony compounds can lead to adverse reactions such as diarrhea,headache,chest tightness,abdominal colic,arrhythmia and nerve injury.With the large-scale production and use of antimony containing products and other natural factors,the problem of antimony pollution in global water is becoming increasingly serious.Antimony exists in the form of Sb³⁺and Sb⁵⁺,in which the toxicity of Sb³⁺is ten times that of Sb⁵⁺.As China is the country with the largest reserves and exploitation of antimony in the world,it is urgent to solve the problem of antimony pollution in China’s water body.For the treatment of wastewater containing antimony,the common methods include adsorption,chemical precipitation,ion exchange and membrane separation.Compared with other treatment methods,adsorption method has the advantages of simple operation,low sludge production,high selectivity for pollutants and high efficiency,which is one of the most promising methods to treat antimony pollution in water.In this study,a Cerium-Manganese binary oxide（CMBO）adsorbent was developed.And a systematic study on the efficacy and mechanism of antimony contamination removal from water bodies by adsorbents was conducted,and the following results were obtained.（1）A series of CMBO were prepared by selecting sodium persulfate,potassium permanganate and hydrogen peroxide as oxidants,and it was found that the sorbent with sodium persulfate as the oxidant and a 10:1 Ce/Mn molar ratio had the best adsorption effect on antimony,which was identified as the adsorbent for this study.The CMBO exist mainly in amorphous form,and are mesoporous materials made of agglomerated particles with particle diameters of 30-50 nm,with rough and porous surfaces,possessing a high specific surface area（107.3 m²/g）and an isoelectric point of 6.45.（2）The CMBO can remove Sb³⁺and Sb⁵⁺from water quickly and effectively,and the maximum adsorption amounts of Sb³⁺and Sb⁵⁺at p H 7.0±0.1 were 260.6 mg/g and 101.1 mg/g,respectively,which were higher than those of Mn O₂（95.6 mg/g and 35.4 mg/g）and cerium dioxide（224.4 mg/g and 96.2 mg/g）.These indicating that CMBO can play a synergistic effect of each component and effectively improve the removal ability of antimony.The pseudo second order model may better describe the adsorption kinetics of Sb³⁺and Sb⁵⁺,which indicates that the sorption is chemical adsorption.The CMBO had good sorption effect on Sb³⁺over a wide range of p H,and the Sb⁵⁺sorption on CMBO was p H-dependent.The effect of ionic strength on the removal efficiency of antimony was not significant.The effects of coexisting anions on antimony sorption decreased in order of:PO₄^3->Si O₃^2->CO₃^2->SO₄^2-.（3）The sorption behavior of CMBO was studied in the copper-antimony binary system.It was found that the sorption of CMBO had both competitive and synergistic adsorption effects on Sb³⁺and Cu²⁺binary systems;the adsorption of Sb⁵⁺and Cu²⁺binary systems had synergistic adsorption effects.In general,CMBO had better adsorption capacity for copper-antimony binary system,and have good application prospects for treating multi-pollutant wastewater.（4）The mechanism of Sb⁵⁺removal by CMBO is:firstly,Sb⁵⁺in solution diffuses to the solid/liquid interface,Sb⁵⁺ligand exchange replaces the metal hydroxyl group on the surface of CMBO,forming inner-sphere surface complexes to remove Sb⁵⁺from solution.Sb³⁺removal is mainly involved with three parts:firstly,Sb³⁺in the solution is adsorbed to the surface of CMBO,then the surface Ce⁴⁺and Mn⁴⁺oxidize Sb³⁺to Sb⁵⁺,the generated Sb⁵⁺,Ce³⁺and Mn²⁺may be directly bound to the adsorbent surface or released into the solution,and finally some of the reduced dissolved ions can be adsorbed by CMBO again to form a stable inner-sphere surface complex.