Study On The Adsorption Of Several Heavy Metal Ions In Water And Loading Of Nano-TiO₂ Using Zr-containing Silica Residue

Zr-containing Silica Residue is a waste slag produced by the acid reaction process in the production of zirconium oxychloride.The purified product?ZSR-P?is mainly composed of amorphous phase SiO₂,with a high specific surface area and a special accumulation structure.The purpose of this paper is to realize the application of Zr-containing Silica Residue in the treatment of water pollution.The removal of several heavy metal ions in water by ZSR-P,the solidification of ZSR-P in cement after adsorption of heavy metal ions and the preparation of composite photocatalyst with ZSR-P as the carrier supporting nano-TiO₂ were studied.By using ZSR-P as an adsorbent,the behavior and mechanism of removing Pb²⁺and Cd²⁺in aqueous solution were studied.The adsorption time,the initial concentration of ions,the amount of ZSR-P,especially the pH value of the solution had a significant influence on the adsorption effect.The adsorption capacity of Pb²⁺and Cd²⁺in the solution were 45.3 mg/g and 30.1 mg/g,respectively,and the removal rate reached 99.9%under optimized conditions.The adsorption isotherms of Pb²⁺and Cd²⁺by ZSR-P conformed to the Langmuir adsorption model,the adsorption kinetics conformed to the kinetic second-order adsorption rate model.The adsorption between SiO₂ and Pb²⁺/Cd²⁺is realized by the reaction between Si-OH and Pb²⁺/Cd²⁺hydroxyl compounds on the surface of SiO₂.The modification of ZSR-P by wet method and the adsorption of Cr???in aqueous solution by modified ZSR-P were studied by using cetyltrimethylammonium bromide?CTAB?as a modifier.The positive surface charge range and?potential value were increased and the isoelectric point increased to pH=6.3 after ZSR-P was modified by CTAB.Under optimized conditions,the adsorption capacity of modified ZSR-P of Cr???was 6.28 mg/g and the removal rate of Cr???was 94.25%.The adsorption mechanism was mainly the electrical attraction between the negatively charged Cr???and the positively charged modified ZSR-P.By using ZSR-P as a carrier,the preparation and characterization of ZSR-P/TiO₂composite photocatalyst were studied by Sol-gel method.ZSR-P/TiO₂ composite photocatalyst was characterized by the uniform dispersion of monodisperse morphology nano-TiO₂ on the surface of ZSR-P or interspersed into the pores,combining in the form of Si-O-Ti bonds.TiO₂ had two crystal phases,anatase and rutile,with a loading amount of 17.14%and a particle size of 7-12 nm.ZSR-P/TiO₂was suitable for degradation of lower concentration pollutants in water.Under optimized conditions,the methyl orange in the solution can be completely degraded,and the degradation performance did not decrease significantly after 4 cycles.The ZSR-P adsorbed Pb²⁺,Cd²⁺and Cr?VI?was cured by cement and the ion stabilization behavior was studied.The results showed that cement curing had a good stable sealing effect on all ions.The cement solidified body with ZSR-P was leached for 1 d in neutral and acidic simulated liquid,and the leaching amounts of Pb²⁺,Cd²⁺and Cr?VI?were 0.1-0.5%and 0.3-0.9%,respectively.The content of each ion in the leaching solution was lower than the allowable value of the national industry standard.The mechanical properties of each cement cured body meet the requirements of national standards.