| In China,the annual consumption of mineral processing reagents was a million tons.The sulfide ore flotation collector was the most widely used,but also the most important type of flotation reagents,which in the mineral processing reagents occupy an extremely important position.Ester-105 was a kind of sulfide ore flotation collector,which has catchability and foaming properties,and it has characteristics of low dosage and high flotation index.But the ester-105 was very difficult to degrade,a large number of residues in mineral processing waste water would be harm to human health and ecological environment.Therefore,to explore an efficient and fast processing technology of mineral processing wastewater has attracted wide attention.Photocatalytic oxidation technology has been widely used in the atmosphere,soil and water pollution control due to its simple operation,mild reaction conditions,easy to use,low energy consumption and no secondary pollution.In this paper,the rare earth element lanthanum doped titanium（La/TiO2）photocatalyst was prepared under the present situation of pollution and control of mineral processing waste water.The photocatalytic degradation characteristics of common sulfide mineral flotation collectors were systematically studied,and the removal effect and degradation process or mechanism of photocatalyst to ester-105 were studied.The research contents and results were as follows:1.The lanthanum-doped titanium（La/TiO2）nano-photocatalyst were prepared by sol-gel method.The prepared photocatalyst were anatase,and the 0.50% La/TiO2（450℃）photocatalyst has mesoporous structure,the pore size distribution was unimodal,the average pore size was 7.78 nm,the specific surface area was 56.1626 m2/g and the isoelectric point was at p H6.5.The doping of La could inhibit the crystal growth of TiO2,increase its specific surface area,thus improving its photocatalytic activity.At the same time prompted the TiO2 response to light intensity was enhanced,absorption edge red shift,response to the visible light,thus it provide a possible for photodegradation of ester-105 by use visible.However,the calcination temperature too high would cause the La/TiO2 to agglomerate and lead the particle size increase,the specific surface area decreases,thereby reducing its photocatalytic activity.2.Floatation collector ester-105 from beneficiation wastewater was taken as the target pollutant.The effect factors of the initial p H value,La doping ratio,calcination temperature,light intensity,amount of catalyst and cyclic utilization of catalyst on photocatalytic activity of the material were investigated.Adsorption characteristics of photocatalyst to ester-105 were also investigated.Different conditions have different effects on the degradation of ester-105.The adsorption of different initial concentrations ester-105 in the surface of catalyst were 30 min basically reached theadsorption equilibrium.The catalyst had the strongest photocatalytic activity to ester-105 when initial p H value was 6.30,La doping ratio was 0.50%,calcination temperatures was 450℃,light was300 W mercury lamp and catalyst dosage was 0.3 g/L.After 70 minutes,the removal rate of ester-105 reached 99.59%.After 4 times of cyclic utilization,the removal rate of the ester-105 was still above 99%,which provided the potential possibility for application of photocatalyst in engineering.3.Inorganic anions,inorganic cations and H2O2 have different effects on the photocatalytic degradation of ester-105 by La/TiO2.The effect of NO3-on the photocatalytic degradation of ester-105 was small,and the Cl-,HCO3-and SO42-had different inhibition effects.Na+,K+,Ca2+ and Mg2+ affected the degradation slightly detriment because they were all in the highest oxidation state.However,Cu2+and Fe3+inhibited the ester-105 photodegradation greatly.Besides,H2O2 did not promote the photodegradation of ester-105 by La/TiO2.4.The adsorption and photocatalytic degradation kinetics behavior of ester-105 were respectively accord with the Langmuir adsorption model and the kinetic model of Langmuir-Hinshelwood.The maximum adsorption was 0.338 mg/g and the adsorption equilibrium constant was 1.008 L/mg of La/TiO2 to ester-105.The first order kinetic reaction rate constant k was influenced by the solution initial concentration,initial p H value and the amount of photocatalyst.k was linear with the initial concentration of ester-105.In theory,the optimal p H value was 6.95 and the optimum dosage of photocatalyst was 0.2739 g/L.The experimental test verified that the reaction of La/TiO2 photocatalytic degradation ester-105 was in accordance with the kinetic model of Langmuir-Hinshelwood.5.·OH and h+ were the active species in the photocatalytic degradation of ester-105 reaction.·OH plays a leading role in the photocatalytic activity.La doping can slow down the quenching of h+ and improve the photocatalytic efficiency.H2O2 can promote the degradation of ester-105.The degradation mechanism and pathway of ester-105 may be: the ester-105 was degraded into a variety of intermediate products,and the intermediate products continued to degrade to form small molecules or groups,some small molecules or groups continued to degrade until harmless.6.The degradation properties of butylxanthate,sodiumdiethyldithiocarbamate,ammoniumbutyldithiophophate,ester-105 and Z-200 were scaning from 200 nm to 600 nm by use UV-VIS spectrophotometer.The results showed that they characteristic absorption wavelength were respectively 301 nm,228 nm,257 nm,275 nm and 242 nm.Ammoniumbutyldithiophophate and butylxanthate were easy to degradation,sodiumdiethyldithiocarbamate,ester-105 and Z-200 were hard to degradation.Collector under mercury lamp irradiation degradation rate was much higher thanunder xenon lamp irradiation degradation rate,photocatalyst can greatly improve the collecting agent degradation. |
