Preparation Of New Phosphorylated Titanium Oxide And Its Adsorption Of Heavy Metal Ions

Heavy metal ion pollution in ecological water body seriously endangers the sustainable development of human society.Chemical methods are commonly used to eliminate harmful ions by chemical precipitation of precipitators,but the chemicals released and the resulting sediments may lead to secondary contamination.The adsorption method removes metal ions by physical or chemical adsorption of materials,which is pollution-free,recyclable and low-cost,and has attracted much attention from researchers.Titanium oxide,as the representative of metal oxides,is a promising low-cost adsorption material.However,it has many disadvantages,such as small specific surface area and weak surface adsorption capacity,which are difficult to meet the removal requirements of low concentration heavy metal ions.Therefore,it is particularly important to design and develop new oxide based adsorption materials with high adsorption capacity,high adsorption efficiency and high selectivity.This paper selected environmentally friendly Ti O₂ as the research object,regulated and optimized the chemical composition,surface potential and surface functional groups of the material at the atomic and molecular level,and prepared a series of new phosphorylated titanium oxide materials with excellent adsorption performance of heavy metal ions.The laws of adsorption thermodynamics/kinetics were summarized,and the mechanism of ion adsorption was elucidated,which provided reference for the rational design and practical application of the new oxide-based adsorption materials.The main achievements of this paper are as follows:（1）A new phosphorylated titanium oxide（PTO）adsorption material with high specific surface area and abundant pore structure was successfully prepared from titanium tetrachloride/phosphoric acid by boiling water assisted precipitation method.Phosphoric acid promoted the formation of a disordered stacked-P-O-Ti-O-network structure formed by[Ti O₆]sub-nano structure and[PO₄]atomic cluster in the hydrolysis process of titanium tetrachloride.The-P-O-Ti-O-network regulated the specific surface area and pore structure in combination with the role of bubble template in boiling water.In the process of heat treatment,the-P-O-Ti-O-network structure can effectively resist the contraction and reconstruction of the channel,retains the mesoporous structure with a high specific surface area（278 m²/g）,with the maximum adsorption capacity of Cr³⁺is 92 mg/g.In the PTO structure,[Mn O₆]is used to replace part of[Ti O₆]to form phosphorylated titanium manganese oxide（PTMO）,and the high-efficiency removal of heavy metal ions is realized through the replacement of manganese ions with heavy metal ions.（2）Based on the research strategy of regulating the type and distribution of surface functional groups,active functional groups with strong complexation with heavy metal ions were introduced to the surface of PTO,and hydroxyl or amino functionalized phosphorylated titanium oxide adsorption materials were successfully prepared by ethanol solvent heating method,thus achieving the adsorption of ppm level heavy metal ions.The introduction of active functional groups on the surface of PTO greatly improved the adsorption sites on the surface of PTO materials.The concentration of Cr³⁺,Fe³⁺,and Pb²⁺can be reduced from～5 mg/L to 0.01-0.03 mg/L,with a removal rate of more than 95%,and the maximum adsorption capacities of Cr³⁺,Fe³⁺,and Pb²⁺were 95 mg/g,190 mg/g,and 510 mg/g,respectively.（3）Based on the mechanism of bifunctional group cooperative adsorption of heavy metal ions,the phosphorylated titanium oxide（SPTO）with rich hydroxyl and amino bifunctional groups and ultra-high adsorption performance was successfully prepared by ethanol solvent thermal method,and the adsorption of heavy metal ions at ppb level was realized.The larger specific surface area（446 m²/g）of SPTO can provide more adsorption sites,and the synergistic effect of surface amino group and hydroxyl group can further improve the complexation of heavy metal ions.SPTO can reduce the concentration of Cd²⁺,Cr³⁺,Fe³⁺,and Pb²⁺from～5 mg/L to 0.001 mg/L,which meets the concentration standard of heavy metal ions in drinking water set by the World Health Organization.In addition,the maximum adsorption capacity of Pb²⁺was 761mg/g,which was much higher than that of other inorganic adsorption materials reported in the literature.（4）A new macroscale preparation method of high efficiency phosphorylated titanium oxide adsorption material was developed,and the engineering application of this kind of adsorption material was explored by simulating the sewage environment.Phosphorylated titanium oxide prepared on a large scale with high adsorption properties can effectively reduce the concentrations of Cd²⁺,Cr³⁺,Fe³⁺,and Pb²⁺in sewage from～5 mg/L to～0.01 mg/L.After 5 regeneration cycles,the removal rates of Cd²⁺,Cr³⁺,Fe³⁺,and Pb²⁺remained at 95%,95%,94%,and 95%,respectively.The effective treatment capacities of wastewater containing Cd²⁺,Cr³⁺,Fe³⁺,and Pb²⁺were 3.2,4.0,4.8,and 5.0 tons per kg of adsorbent,respectively.This study provided the experimental basis and theoretical guidance for the development of efficient adsorption materials for the removal of heavy metal ions from water.