Study On The Effect Of Nano Metal Oxide Surface Modification And Nitrogen Doping On Adsorption And Photocatalytic Performance

As the pre-treatment technology for environmental water samples,the preconcentration with adsorption and the photocatalytic oxidation have obvious advantages on the improvement of analytical performance and environment-friendly.?1?Through an ester-like bond,titanium dioxide?TiO₂?nanoparticles were surface modified with benzoic acid and phosphoric acid by a simple and one-step chemical adsorption method.The surface characteristics of TiO₂ were improved with negatively charged,hydrophilic,and hydrophobic,and oxygen affinity at the same time.Using the optimal dose of benzoic acid,phosphoric acid and irradiation with Xenon lamp for 2 h,benzoic acid and phosphoric acid,the photodegradation ratio of RhodamineB as cationic dyes was improved from 54.9%to 71.5%,72.8%,91.2%.After surface co-modification,the synergistic effect from oxygen affinity of phosphate groups and hydrophobicity of phenyl group could be used to overcome the major obstacles of heterogeneous photocatalysis for the poor surface coverage of the pollutants on the catalyst and the rapid consumption of oxygen on the TiO₂ surface.The photodegradation ratio was enough for the requirement of sample pretreatment for the determination of COD and TOC.?2?A new type of photocatalyst,nitrogen doped MoO₃,was synthesized for the sample pretreatment.The effects of synthetic temperature and doping ratio on the adsorption properties of metal ions and the degradation of organic pollutants for nitrogen doped MoO₃ were investigated.The optimal synthetic temperature and doping ratio were 430?and 1:9,respectively.The degradation rate of Rhodamine B?30 mg/L?for two hours was 59.98%,which was 3.17 times of P25.The rhodamine B?10 mg/L?adsorption ratio was 92.83%for 55 minutes.At the same time,the outstanding metal adsorption performance for nitrogen-doped MoO₃ was observed.The adsorption rates were 76.63%,92.36%and 94.45%,respectively,for 25,10,and5 mg/L of Fe???.The adsorption rates of Pb????25,10,5 mg/L?were 83.21%?94.88%?and 97.12%,respectively.When the concentration of Fe???or Pb???was less than 10 mg/L,their adsorption rates were more than 90%and could be used for the sample preconcentration.When multiple metal ions were coexisted,the adsorption rates for Fe???and Pb????25mg/L?were decreased into 55.62%and 70.84%,indicating that same surface adsorption sites were shared for these two kinds of metal ion,but if their concentrations were less than 8 mg/L,their adsorption rates were also suitable for sample pretreatment.?3?A new method for the determination of Fe???in water was established by the combined technique of adsorption enrichment,photodegradation for interference removal,and colorimetric sensing with high selectivity.Using acrylic resin as a fixative,the nitrogen-doped MoO₃ was fixed into the cellulose filter paper by self-assembly and then to the separation and recovery of nanomaterials were solved.The adsorption capacity of iron was high as 31.05 mg/g.Selective coloration of Fe???could be achieved with o-phenanthroline.The interference of colored material on the cellulose filter paper could be avoided by the good photodegradation ability of nitrogen-doped MoO₃.Combined with smart phones and image processing software,the change of gray-scale could be analysed for the determination of Fe???.The method is suitable for the field detection of Fe???,which linear range,correlation coefficient,and detection limit were 0.05-5 mg/L,0.976,and 0.05 mg/L,respectively.Its results of water samples were consistent with flame atomic absorption spectrometry.