Electroanalysis Of Nitrophenols On Several Nanoporous Gold Films

Nitrophenol and its derivatives are important organic raw materials for industrial production.They are widely involved in the industrial synthesis of pesticides,dyes,paints and pharmaceuticals.Wastewater containing nitrophenolic compounds is discharged into the water and soil environment.It has caused serious environmental pollution problems.Among them,4-nitrophenol(4-NP)and 2-nitrophenol(2-NP)are more toxic and listed in the US Environmental Protection Agency's list of priority pollutants.In this paper,differential pulse voltammetry(DPV)technique was used to detect 4-NP and 2-NP on several nanoporous gold film electrodes.The main contents are as follows:(1)The nanoporous gold film was prepared in KCl solution by one-step rapid anodic potential step method to obtain D-NPG electrode,which was used for electrochemical detection of 4-NP and 2-NP.The effects of the electrode on the different electrolytes,sweep speed,accumulation time and accumulation potential in 4-NP electrochemical analysis and its anti-interference,storage stability and measured properties were investigated.The electrochemical analysis of 4-NP and2-NP by D-NPG electrode has a high current response,but simultaneous detection of two substances cannot be performed.Only 4-NP can bedetected separately,and the 4-NP has wide linear range(0.01~20 ?M),low detection limit(3.5 nM),good anti-interference,and this electrode can be used for electrochemical detection of 4-NP in real water samples,but its selectivity and storage performance need to be improved.(2)A three-dimensional micro-nano hierarchical porous gold(S-NPG)film was prepared in NaOH solution with square wave pulse potentials(SWPPs)and used for the detection of 4-NP and 2-NP by DPV.The S-NPG is prepared from smooth gold by repeated pulse oxidation-reduction and simutaneous hydrogen evolution in a NaOH solution.The surface is a typical honeycomb morphology,and the porous walls are composed of irregular long strips of gold nanopolyhedrons.Such a microporous structure is beneficial to electron and mass transfer,therefore can increase the electrochemical activity of the electrode.The S-NPG electrode can simultaneous electrochemical detection of 4-NP and2-NP and has a high current response.The 4-NP and 2-NP detection ranges are wide(4-NP: 0.1~5 ?M;2-NP: 1~40 ?M),low detection limit(4-NP: 1.2 nM;2-NP: 27 nM),good selectivity,good anti-interference,good storage performance,and this electrode can be used for electrochemical detection of 4-NP and 2-NP in real water samples.(3)The nanoporous gold(DS-NPG)film was prepared by combining the anodic potential step method and square wave potential pulse method,which was used for electrochemical detection of 4-NP and2-NP.The nanoporous film was prepared firstly in KCl solution by one-step rapid anodic potential step method,and then treated in NaOH solution under repeated oxidation-reduction and simutaneous strong hydrogen evolution,and its stability is higher than that of the D-NPG electrode.The electrochemical performances of DS-NPG electrode on4-NP are between D-NPG electrode and S-NPG electrode,which can simultaneously detect 4-NP and 2-NP.Its 4-NP and 2-NP detection range is wide(4-NP: 0.1~20 ?M;2-NP: 3~100 ?M),and the detection limit is low(4-NP: 2.3 nM;2-NP: 99 nM),good selectivity,good stability,good anti-interference,good storage performance,and this electrode can be used for electrochemical detection of 4-NP and 2-NP in real water samples.