Organic Pollutants Treatment Using Titanium Dioxide Dual Rotating-disks Photocatalytic Fuel Cell

TiO₂ photocatalytic technology has made significant progress in many aspects such as sterilization,air purification,mouldproof,deodorant,anti-fouling self-cleaning,water splitting,hydrogen,organic pollutants degradation and solar cells since it was deeply researched in 1972.But as a new kind of advanced oxidation technologies to treat wastewater,it has only been studied in laboratory.Although a lot of works have been done relating to modify the microscopic structure of TiO₂ film,enlarge TiO₂ film electrode areas,select suitable electrode substrate,and build TiO₂ composite materials.Some achievements have been achieved such as expand the utilization scope of excitation light,improve the utilization efficiency of excitation light and eliminate the rapid recombination of electron-hole pairs,however,the development of photocatalytic reactor hasn't been promoted enough,the traditional tubular reactor has shown some design flaws:?1?Incident light has been absorpted seriously by reaction meida;?2?the speed of mass transfer is low;?3?reactor setup is high energy-consuming and complex.Therefore designing of high efficiency,low consumption of photocatalytic reactor has become the inevitable choice to promote the further development of photocatalytic technology in wastewater treatment field.Aiming at the defects of traditional photocatalytic reactor,and on the basis of our previous research results,we designed a dual-chambers rotating-disks photocatalytic fuel cell system.Not only reduces the absorption effect by the reaction media,but also strengthens the mass transfer efficiency.At the same time,the rapid recombination between anodic oxidation products and cathodic reduction products has been diminished greatly.Besides that,stronger photocurrent has been transferred from anode to cathode.The main research contents are as follows:1.A TiO₂/Ti planar electrode was prepared by sol-gel method and it was used as the anode of the dual rotating-disks photocatalytic aqueous film reactor to investigat working parameters.A Cooper rotating-disk with the same area was used as the cathode.Rhodamine B?RhB?solution was used as the simulated dye wastewater.The concentration of RhB was 25mg·L^-1.Total 400 mL RhB solution was poured into anode cell and cathode cell.The results of background experiments and reaction parameter experiments showed the optimal treatment conditions.The initial pH value of RhB solution was 2.5 and rotating speed was 70 rpm.After120 min photocatalytic degradation process,color removal efficiencies of anode cell and cathode cell were 56.4%and 43.4%.The TOC removal efficiencies were 29.5%and 23.1%.Photocurrent output value was 0.35 mA and electric current density was 78.5 mA·m^-2.2.The salt bridge connection was raplaced by a proton exchange membrane to modify dual rotating-disks photocatalytic aqueous film reactor.Using sol-gel TiO₂/Ti planar electrode as the anode,Cu electrode as the cathode to degrade 25 mg·L^-1 of RhB dye wastewater.After120 min photocatalytic degradation process,color removal efficiencies of anode cell and cathode cell were increased to 77.5%and 58.5%.Photocurrent output value was increased to0.48 mA and electric current density was 107.41 mA·m^-2.3.Two kinds of TiO₂ nanotubes?TNAs?electrodes were prepared by anodic oxidation method using 0.5%HF-H₂O system and 2 wt%NH₄F-0.3 wt%H₂O-ethylene glycol system.?1?Surface morphology test showed that organic TNAs/Ti electrode was structured than inorganic TNAs/Ti electrode.Futhermore,organic TNAs/Ti electrode had bigger inner diameter.Compared to TiO₂/Ti planar electrode,organic TNAs/Ti electrode had larger specific surface area,thus had a stronger ability to capture incident light;?2?XRD results showed that both organic TNAs/Ti electrode and inorganic TNAs/Ti electrode were anatase;?3?Photocurrent output value which was motivated by inorganic TNAs/Ti electrode was 0.59mA and electric current density was 130.37 mA·m^-2.Photocurrent output value motivated by organic TNAs/Ti electrode was 0.82 mA and electric current density was 181.67 mA·m^-2;?4?Used inorganic TNAs/Ti electrode as the anode,Cu electrode as the cathode to degrade 25mg·L^-1 of RhB dye wastewater.After 120 min photocatalytic degradation process,color removal efficiencies were increased to 97.7%and 81.0%.When used organic TNAs/Ti electrode as the anode,color removal efficiencies were increased to 97.5%and 89.1%;?5?Used 2 pieces of Cu electrode as the cathode to degrade 25 mg·L^-1 of RhB dye wastewater.After 120 min photocatalytic degradation process,color removal efficiency of cathode cell was increased to 93.2%.It showed that a side reaction was occurred in cathode chamber.The side reaction was 4H⁺+O₂+4e^-?2H₂O.4.Based on the research of the dual rotating-disks photocatalytic aqueous film reactor,a concept of dual-cells rotating-disks photocatalytic fuel cell was exhibited.The verification experiments of H₂O₂,·OH,h⁺,N₂ and O₂ effect tests modified the mechanic research results.5.Used organic TNAs/Ti rotating-disk electrode as the anode of the dual rotating-disks photocatalytic fuel cell,Cu rotating-disk electrode as the cathode to degrade RhB,reactive brilliant red X-3B,methylene blue,bisphenol A,glucose separately.The test results showed the dual rotating-disks photocatalytic fuel cell had a certain degree of degradation ability to each target compounds.The degradation efficiencies of anode chamber were from69.8%to 96.8%,the degradation efficiencies of cathode chamber were from 55.0%to90.1%.About RhB solution,the COD removal efficiencies were 88.8%and 67.7%.6.Based on the wedge-surface Ti electrode,TiO₂ nanopore microstructure was prepared by anodic oxidation method using 2 wt%NH₄F-0.3 wt%H₂O-ethylene glycol system.Hemoglobin film was prepared by impregnation method on the surface of graphite electrode.Used TiO₂ wedge-surface nanopore anode and Hemoglobin/graphite cathode in the dual rotating-disks photocatalytic fuel cell,a new photocatalytic/biological enzyme complex fuel cell was exhibited.?1?The shape and size of the TiO₂ nanopore are irregular.The scope of its diameter is about 200⁵00 nm;?2?In the process of photocatalytic degradation,electrons were transferred from anode Ti substrate to cathode graphite substrate.·OH was synthesized due to the iron porphyrin activity center of Hemoglobin.In fact,·OH was the main driving force to degrade target compounds;?3?Used TiO₂ wedge-surface nanopore anode and different cathode to degrade RhB solution,the color removal efficiency of these cathodes:hemoglobin/graphite electrode>Cu electrode>graphite electrode.