Preparation Of Ti Oxide Adsorbent And Its Adsorption Characteristics Of As(Ⅲ)from Water

In our country drinking water arsenic pollution is serious, the adsorption method of arsenic removal because of advantages of high treatment efficiency, strong anti-interference ability, low cost, adsorbent can be repeatedly used and the water will not cause secondary pollution have been research extensively. In this paper several laboratory preparation of titanium oxide have been used as adsorbents for arsenic removal. Effects of contact time, initial As concentration, adsorbent dosage, temperature, pH, co-existing anions on As adsorption were intensively investigatedThe results show that, at35℃the adsorption kinetics of TiO2and Ti(OH)4well agrees with Lagergren pseudo-second order model(R2>0.99). Freundlich and Langmuir isotherm can fit of the adsorption process, but the Freundlich equation fitting better.The constant1/n is larger than0.5,indicating that the adsorption process is not easy to occur. The saturated adsorption capacity of TiO2and Ti(OH)4obtained by fitting the Langmuir equation were7.78and20.58mg/g. Effect of pH on the adsorption of As (III) is more obvious, TiO2in the pH value of about5, the reaction rate coefficients up to0.4182, Ti(OH)4in the pH value of about9, the reaction rate coefficient up to0.2291.Lagergren pseudo-second order equation fitting results show that, at the start of the reaction of300min, Ti-Ca composite oxide adsorption rate increased significantly than Ti-Fe composite oxide. Ti-Fe and Ti-Ca composite oxide, on the As(III) adsorption both performance the initial phase of rapid adsorption and subsequent slow sorption process. The initial rapid adsorption stage is mainly the result of boundary layer effect. After surface adsorption reached saturation, began to appear on internal diffusion. TF, TM, and Ti-Ca composite oxide by the Langmuir equation to fit the maximum adsorption capacities were60.61,38.76and74.07mg/g respectively. As the temperature increas, rate constant of adsorption and adsorption amount are getting higher. When the temperature is40℃, the adsorption rate constant can reach2times of10℃, but the growth of adsorption amount is relatively weak. Therefore, elevated temperature can improve the adsorption rate, but has little effect on the adsorption of the final. When exsit the PO43-,Ti-Fe and Ti-Ca composite oxide adsorption and removal of As(III) has the obvious inhibitory action, it may be because:phosphate and arsenate has very strong chemical similarity, in solution they have similar molecular structure and deprotonation constants. Therefore, phosphate and arsenate competition the surface adsorption sites, so that the arsenic removal rate decreased.