The adsorption potential of titanium dioxide （TiO2） nanoparticles for removing arsenic from drinking water was evaluated. Pure and iron-doped TiO2 particles are synthesized via sol-gel method. The synthesized TiO2 n...The adsorption potential of titanium dioxide （TiO2） nanoparticles for removing arsenic from drinking water was evaluated. Pure and iron-doped TiO2 particles are synthesized via sol-gel method. The synthesized TiO2 nanoparticles were then immobilized on ordinary sand for adsorption studies. Adsorption isotherms were conducted on the synthesized nanoparticles as well as the sand coated with TiO2 nanoparticles under varying conditions of air and light, namely, the air-sunlight （A-SL）, air-light （AL）, air-dark （AD） and nitrogen-dark （ND）. X-ray diffraction （XRD） analysis showed that the pure and iron-doped TiO2 nanoparticles were in 100% anatase crystalline phase with crystai sizes of 108 and 65 nm, respectively. Adsorption of arsenic on the three adsorbents was non-linear that could be described by the Freundlich and Langmuir adsorption models. Iron doping enhanced the adsorption capacity of TiO2 nanoparticles by arresting the grain growth and making it visible light responsive resulting in a higher affinity for arsenic. Similarly, the arsenic removal by adsorption on the sand coated with TiO2 nanoparticles was the highest among the three types of sand used. In all cases, As（V） was adsorbed more compared with As（Ⅲ）. The solution pH appeared to be the most important factor in controlling the amount of arsenic adsorbed.展开更多
Nitrogen and sulfur doped titanium dioxide photocatalysts were prepared by the sol-gel method.The products were characterized by X-ray diffraction （XRD）,transmission electron microscopy （TEM）,and UV-visible diffus...Nitrogen and sulfur doped titanium dioxide photocatalysts were prepared by the sol-gel method.The products were characterized by X-ray diffraction （XRD）,transmission electron microscopy （TEM）,and UV-visible diffuse reflectance spectra （DRS）.Photocatalytic activities of the samples were investigated on the degradation of methyl orange （MO）.The effect of the dopants on the electronic structure of TiO2 was studied by the first-principles calculations based on the density functional theory （DFT）.The orbital hybridization resulted in energy gap narrowing and electronic delocalization in the crystal of doped TiO2.Mobile electrons of varied energetic states could offer enhanced electron transfer,together with optical absorption improvement.The results show that the doping elements of N and S play a cooperative role in the modification of electronic structure,which enhances the photocatalytic performance.The experimentally observed absorption edges of N-doped TiO2,S-doped TiO2,and N,S-codoped TiO2 are 420,413,and 429 nm,respectively,which can be explained by the theoretical calculation results.展开更多
文摘The adsorption potential of titanium dioxide （TiO2） nanoparticles for removing arsenic from drinking water was evaluated. Pure and iron-doped TiO2 particles are synthesized via sol-gel method. The synthesized TiO2 nanoparticles were then immobilized on ordinary sand for adsorption studies. Adsorption isotherms were conducted on the synthesized nanoparticles as well as the sand coated with TiO2 nanoparticles under varying conditions of air and light, namely, the air-sunlight （A-SL）, air-light （AL）, air-dark （AD） and nitrogen-dark （ND）. X-ray diffraction （XRD） analysis showed that the pure and iron-doped TiO2 nanoparticles were in 100% anatase crystalline phase with crystai sizes of 108 and 65 nm, respectively. Adsorption of arsenic on the three adsorbents was non-linear that could be described by the Freundlich and Langmuir adsorption models. Iron doping enhanced the adsorption capacity of TiO2 nanoparticles by arresting the grain growth and making it visible light responsive resulting in a higher affinity for arsenic. Similarly, the arsenic removal by adsorption on the sand coated with TiO2 nanoparticles was the highest among the three types of sand used. In all cases, As（V） was adsorbed more compared with As（Ⅲ）. The solution pH appeared to be the most important factor in controlling the amount of arsenic adsorbed.
基金supported by the Outstanding Adult-Young Scientific Research Encouraging Foundation of Shandong Province(No.2008BS09016)the Scientific Research Program of Shandong Province Education Department,China (No.J08LC55)
文摘Nitrogen and sulfur doped titanium dioxide photocatalysts were prepared by the sol-gel method.The products were characterized by X-ray diffraction （XRD）,transmission electron microscopy （TEM）,and UV-visible diffuse reflectance spectra （DRS）.Photocatalytic activities of the samples were investigated on the degradation of methyl orange （MO）.The effect of the dopants on the electronic structure of TiO2 was studied by the first-principles calculations based on the density functional theory （DFT）.The orbital hybridization resulted in energy gap narrowing and electronic delocalization in the crystal of doped TiO2.Mobile electrons of varied energetic states could offer enhanced electron transfer,together with optical absorption improvement.The results show that the doping elements of N and S play a cooperative role in the modification of electronic structure,which enhances the photocatalytic performance.The experimentally observed absorption edges of N-doped TiO2,S-doped TiO2,and N,S-codoped TiO2 are 420,413,and 429 nm,respectively,which can be explained by the theoretical calculation results.
