Longwen Li,Lin Chi,Hongxu Zhang,Shuming Wu,Han Wang,Zhimin Luo,Yanwei Li,Yanhui Li
This article prepared a nanoparticle (NP) Ti-PDA made from bis (2-hydroxy propionic acid) diammonium titanium hydroxide (Ti-BALDH) chelating dopamine (DA), as a photocatalyst to absorb and reduce hexavalent chromium (Cr(VI)) under visible light with recycling ability from waste water. Ti-PDA NPs with part of TiO 2 -like structure can perform some function of TiO 2 , while participation of PDA will not only broaden absorption spectrum from UV to visible light, but offer the ability to absorb Cr(VI). Compared with TiO 2 Ti-PDA NPs would make full use of sunlight, increasing the photocatalytic efficiency. The adsorption results of Ti-PDA NPs for Cr(VI) showed that the adsorption capacity of Ti-PDA NPs can reach 500.24 mg/g when the concentration of Cr(VI) was 300 mg/L, and the adsorption data matched well with the Langmuir isotherm model, and confirmed to a quasi-second-order dynamics. Under visible light irradiation, Ti-PDA NPs could reduce Cr(VI) to Cr(III) within 30 min, and can almost completely reduce Cr(VI) within 15 min even at pH = 4. After three cycles, photocatalytic reduction efficiency was still 95.02%. Thereby the toxic Cr(VI) can be effectively eliminated by Ti-PDA NPs from sewage. As a result, Ti-PDA will be a promising green photocatalyst to remove Cr(VI) in disposal of water pollution.
Wenlong Li,Ludan Shang,Dafei You,Hao Li,Han Wang,Lijuan Ma,Xinna Wang,Yanwei Li,Yanhui Li
In this paper, we synthesized a core-shell structured Fe 3 O 4 @Ti-PDA nanoparticles as photocatalyst by a facile method in environmental friend mild reaction conditions without organic solvent . Firstly, Fe 3 O 4 was synthesized by solvothermal method, and Fe 3 O 4 @PDA was formed by dopamine (DA) self-polymerization to encapsulate Fe 3 O 4 to form polydopamine (PDA) lager. Then, the surface of Fe 3 O 4 @PDA was wrapped by coordinating bis(2-hydroxypropionic acid) diammonium dihydroxide(Ti-BALDH) with DA combined DA self-polymerizing to obtain Fe 3 O 4 @Ti-PDA. As control, we synthesized another photocatalyst Fe 3 O 4 @PDA@TiO 2 . Compared with Fe 3 O 4 @PDA@TiO 2 (band gap 3.0 eV), Fe 3 O 4 @Ti-PDA had a narrower band gap (2.5 eV) and a wider light absorption range (from ultraviolet to visible light to near-infrared light), as a photocatalyst, which can make full use of sunlight to improve photocatalytic efficiency. Meanwhile, magnetic core of Fe 3 O 4 @Ti-PDA made it was easy to separate from aqueous solution for convenient recovery. Using methylene blue (MB) as model pollutant, the degradation efficiency of Fe 3 O 4 @Ti-PDA on MB reached to 92.4% under visible light irradiation for 120 min without cocatalyst, while for Fe 3 O 4 @PDA@TiO 2 only to 32.5%. The result indicated Fe 3 O 4 @Ti-PDA enabled photocatalytic oxidation and rapid separation when photogenerated electron-hole pairs were generated. After three recycles, the degradation efficiency of Fe 3 O 4 @Ti-PDA on MB still remained at 86.47%, showing good recycle stability.
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