Preparation Of Eucalytus Pulp Fiber/Doping Titanium Dioxide Composite Sheet And Its Performance For Degradating The Phenol In Wastewater

The removal of phenol in wastewater has attracted increasingly concern in the world.Photocatalytic degradation of phenol in wastewater by semiconductor photocatalyst TiO2 has become one of the most attractive mothods in the removal of phenol in wastewater.However,the utilization efficient of TiO2 under visible light is still low,and the separation of powdered photocatalyst is very difficult.In this paper,the current advances of the separation and removal of phenol from wastewater as well as the development of TiO2 doping and loading methods were reviewed.The three dimensional(3d)metal doped TiO2 was designed based on the first principles of the quantum chemistry.The composite board based on the eucalyptus pulp bearing metal-doped-TiO2 was prepared by using the pulpboard production technique.The composite board was designed to degrade the phenol in the wastewater via synergistic effect of the adsorption and the catalytic oxidation by doped-TiO2 and adsorbents,respectively.The effect of the composite board on the phenol degradation was investigated.The surface degradation mechanism of phenol molecules was expected to be revealed by the simulated calculation of the degradation effect of phenol molecules on the TiO2 crystal face and metal-doped-TiO2 crystal face,respectively,based on the first principles.The main results and conclusions are drawn as follows:1)Through constructing the 4×4×1 supercell of the anatase TiO2,the geometric structure and electronic structural properties of different 3d transition metal-doped TiO2 were investigated.The results showed that the Fe-doping into TiO2 could have insignificant influence on the geometry structure of TiO2 crystal,and some isolated impurity state could appear in the band gap of TiO2,acting as transition energy,and thus reducing the electron transition energy.Therefore,a redshift phenomenon appears,leading to a great improvement of the photocatalytic degradation ability of the Fe-doped TiO2 on the phenol under visible light.2)The Fe-doped TiO2(FET)particles were synthesized by the sol-gel method,and their characterization and performance on the phenol degradation were investigated.Thermogravimetry(TG)and X-ray diffraction(XRD)analyses showed that the the crystal morphology of anatase TiO2 can be effectively achieved at a thermal decomposition temperature of above 400?,and then the photocatalytic activity of FET particles on the phenol under the ultraviolet and visible light could be enhanced.3)The preparation technique of TiO2 composite board was investigated and the effect of the pulp fiber and additives on the flocculation efficiency of the composite board was evaluated.The results show that the combination of PD/APAM flocculation system was much better for flocculating the inorganic powders and pulp fibers than the independent PD flocculation system or the independent APAM flocculation system,and improved the mechanical properties of the pulp board.The FET/activated carbon composite board had better photodegradation effect on the phenol dissolved in a low concentration aqueous solution.4)The structural changes and the charge form of the phenol molecule on the surfaces of TiO2(001),TiO2(100),FET(001),and FET(100)were investigated according to the three different configuration of phenol molecule.The result showed that the structure of phenol molecules had potential varieties of the crystal surface including the cracking of the benzene ring and the formation of benzoquinone through charge recombination within the phenol ring.The Fe-doping for TiO2 crystal resulted in a strong interaction between FET crystal and phenol molecules,leading to improved adsorption ability for phenol molecules on the surface of FET crystal when compared to the pure TiO2 crystal.Namely,the doping of Fe enhances the photodegradation reaction of the phenol on the crystal surface of the FET,which is helpful for the structure change of phenol molecules subsequently.The main innovation points of this research are as follows:1)A novel preparation method for loading TiO2 on the pulp board was provided with the advantages of easy-separation,low cost and high reusability.By using the pulp board as the carrier for the metal-doped-TiO2 and absorbent,the prepared composite board could be used to completely degrade the phenol dissolved in the low concentration phenol solution.2)The band structure and state density of phenol molecules in the crystal surface of TiO2 were calculated firstly in this paper.And the potential changes of phenol molecular structure on TiO2 crystal surface were analyzed.The possible ways of degradation of the phenol molecules were also investigated.The degradation mode of the phenol molecules was inferred.This work provides the scientific basis of the design and preparation of the modified-photocatalyst with high photocatalytic ability.