Study On The Adsorption And Photocatalytic Properties Of Arsenic In Water By Solidified Synthetic Material Of Arsenic-rich Pteris Vittata L.

Pteris Vittata L.,a hyper-accumulator plant,is a typical remediation plant successfully applied to treat arsenic-contaminated soil.With the widespread promotion of phytoremediation technology,a large number of Pteris Vittata needs to be post-processed,or improper treatment can easily cause"secondary pollution."Therefore,how to carry out the"three transformations"treatment of Pteris vittata after remediation is an important problem in the research of phytoremediation technology of contaminated soil.In this paper,the following three methods are used to treat arsenic-rich Pteris Vittata and use the solidified materials to removal arsenic from water:（1）The hydrothermal carbonization method uses ammonia to adjust the p H to realize the curing of arsenic-rich Pteris Vittata and synthesize the ilmenite/P.vittata hydrothermal material（Fe₃O₄/NH₄Cl/C）.The p H of the precursor liquid and the type of the precursor liquid are changed during preparation.When the Pteris Vittata is solidified with ilmenite solution at p H 7,0.8%of the total arsenic in Pteris Vittata was extacted,and only 0.03%of the total arsenic was leached.There is no volatile arsenic,and 38.4%of the arsenic is solidified in Fe₃O₄and NH₄Cl materials based on amorphous carbon,but the solidification effect needs further analysis.When using UV photocatalytic oxidation of 1ppm As（III）,the removal rate is 95.1%.Compared with the removal rate of 92.6%of the ilmenite hydrothermal material（Fe₃O₄/NH₄Cl）,the removal rate of arsenic is better。（2）The arsenic-rich Pteris Vittata was solidified by the supercritical drying method and TiO₂aerogel material（P.vittata-TiO₂）was synthesized.The amount of Pteris Vittata digestion solution added was changed during the preparation process.When 1m L of digestion solution is added,no arsenic was extacted,only 0.02%of the total arsenic was leached.Low volatile arsenic accounts for only 3.7%of the total arsenic in Pteris Vittata.96.5%of the arsenic is solidified in the TiO₂aerogel,compared to adding 0.1m L digestion solution,the solidification effect of the two is equivalent.When 10ppm As（III）is oxidized by UV photocatalytic oxidation,the removal rate is 80.1%,which is better than the removal rate of 52.9%of pure TiO₂aerogel.（3）The arsenic-rich Pteris Vittata was solidified by the biological template method and the Al₂O₃material（P.vittata/Al₂O₃）was synthesized,and the type of precursor was changed during preparation process.When Al₂（SO₄）₃was used as the precursor,1.6%of the total arsenic in Pteris Vittata was extacted,only 0.01%of the total arsenic was leached,volatile arsenic accounts for 13.5%of the total arsenic,and 84.8%of the arsenic was solidified in Al₂O₃,which was equivalent to the solidification ability of Pteris Vittata biological template TiO₂（83.4%）.The adsorption rate of this material for1ppm As（III）is only 12.7%,while the adsorption rate for 1ppm As（Ⅴ）is 92.8%.The Langmuir model obtains As（V）q_maxas 10.18mg/g.It fits well the Lagergren pseudo-second-order kinetic model（R~2=0.99379）,and the adsorption rate constant is0.0375g/（mg·min）.It has a good ability to adsorb As（Ⅴ）.The arsenic content of the material synthesized by curing the arsenic-rich Pteris Vittata under the best conditions:P.vittata-TiO₂aerogel>P.vittata/TiO₂>P.vittata/Al₂O₃,Fe₃O₄/NH₄Cl/C need further analysis.In the performance test of removing arsenic from water,the effect of P.vittata-TiO₂aerogel is the best（97.3%）when UV photocatalytic oxidation of 1ppm As（III）,the Fe₃O₄/NH₄Cl/C material has the best effect when adsorbing As（III）（86.6%）.Therefore,when the arsenic-rich Pteris Vittata is cured and synthesized by the supercritical drying method to synthesize TiO₂aerogel materials,the effect of curing and removing arsenic from water is better.