Adsorption Efficiency And Mechanism Of Arsenic And Fluorine By Al-mn-oxide Load Sawdust

As people’s emphasis on health and public health, arsenic in drinking water and excess fluorine pollution problem more and more get the attention of people. This study is about the sawdust as the carrier modified by Al-Mn-oxide, making modified sawdust particles adsorbent. using sawdust as a carrier of the adsorbent, not only make full use of agricultural waste, can also find a economic, environmental friendly adsorption material. And the surface features、the adsorption efficiency and studying adsorption mechanism of removing fluorine、arsenic of modified sawdust are discussed in this paper. The main results were as follows:1. The surface structure of modified sawdust was researched based on SEM, FTIR, BET, XPS. the modified sawdust in 1055 cm-1 type(-OH) bending vibration peak highlights compared with the original sawdust. The surface of modified sawdust has particle aggregation, makes the specific surface area increased from 0.757 m2/g to 34.04m2/g. The mensuration of modified sawdust is 1.485 mg/g,The aluminum of modified sawdust is 40.864 mg/g.2. Experiments show that the optimal dosing quantity of adsorbent is 1 g/L through the dosing quantity.The adsorption of F was bad in p H=3, because there were many Al3+ dissolution in p H=3,and with F- generated [Al F]2+、[Al F2]+、Al F3 while the surface of the adsorbent positively charged(p Hpzc=5.21); The adsorption of As(III) was good in p H=3 while the oxidation capacity of modified sawdust is strongest, and As(III) is oxided into As(V) before adsorped by modified sawdust. The adsorption of As(V) was good in p H=3, the As(V) was direct adsorped by modified sawdust, and is not same with the adsorption process of As(III).3. Through the dynamic experiment, the power model can well explain the dynamics of adsorption F data, Fitting R2 value is higher, it shows that the surface of modified sawdust have different adsorption active sites. the pseudo-second-order and Power models were the best choice to describe the adsorption kinetics of As(III), by particle diffusion model, the modified sawdust adsorption of As(III) is mainly diffusion control adsorption rate in the granules, but not the only one control factors; the Power models were the best choice to describe the adsorption kinetics of As(V).4. By isothermal experiments, it can better describe the modified sawdust adsorption of F and As(III) by Freundlich、Langmuir isotherm model, the largest adsorption quantity qm respectively reached 27.68 mg/g and 29.95 mg/g; it can better describe the modified sawdust adsorption of As(V) by Freundlich isotherm model,compared to the original sawdust, adsorption capacity of modified sawdust for As(V) increased significantly.5. By the coexistence anion experiment. It has smaller negative effects on the adsorption F with anionic; It has negative effects on the adsorption As(III) 、As(V) with anionic, PO43- is the biggest influence on adsorption of As(III) 、As(V),because the P and As is kin element.6.It can be seen p H、flow、height of packing layer、initial solution concentration all have influence on the penetration curve of F by fixed-bed column. As the initial concentration of As(III) is 100 μg/L, It can be seen that 112 h reached 10μg/L;As the initial concentration of As(V) is 150μg/L, It can be seen that 348 h reached 10μg/L,it can keep a long time about the adsorption of As(V) than adsorption of As(III) with the effluent concentration is below 10μg/L.