Research On Properties Of Corrosion Inhibitors With Low Phosphorus Content And Its Application In Metal Cleaning Agent

The corrosion inhibition of organic corrosion inhibitors with low phosphorus content,2-phosphonobutane-1,2,4-tricarboxylic acid(PBTCA)and 2-hydroxyphosphonoacetic acid(HPAA),was investigated using Q235 steel as substrate material.And then the compounding technique was adopted to reduce phosphorus pollution and to improve corrosion inhibition properties.This research would optimize corrosion inhibition properties and achieve wide application in the field of metal cleaners.The effects of pH value,the mass concentration of PBCTA and temperature on the inhibition rate were observed via single factor analysis.The optimized values and the optimized interval of three parameters were obtained.The optimal value of pH was 9,and the interval was 8~10.The optimal value of the mass concentration of PBTCA was 25 mg/L,and the interval was 20~30 mg/L.The optimal value of temperature was 50 ?,and the interval was 45~55 ?.Based on single factor sensitivity analysis,the effects of mass concentration and temperature on the inhibition rate of HPAA system were also investigated.The optimal value of the mass concentration of HPAA was 23 mg/L,and the interval was 20~26 mg/L.The optimal value of temperature was 50 ?,and the interval was 45~55 ?.Based on optimization interval achieved by single factor analysis,the application conditions of PBTCA were further optimized by Orthogonal Experimental Design and the optimum parameters were obtained as follows:pH was 9,mass concentration was 30 mg/L,temperature was 45 ?.The maximum inhibition rate was 84.5% under this condition.HPAA parameters were optimized by Response Surface Methodology(RSM)and the optimum conditions were listed as follows:pH of 9,mass concentration of 23 mg/L,temperature of 50 ?.The maximum inhibition rate was 68.68% under this condition.The corrosion inhibition rate of HPAA obtained by RSM was low and it was necessary to improve the corrosion inhibition rate through compounding technique.The results of compounding experiments indicated that the corrosion inhibition rate was 93.75% when ?(HPAA):?(Na2MoO4):?(Na2B4O7)=0.5:0.5:0.4.The EIS spectra of the compound corrosion inhibition exhibited that impedance radius was the largest,proved that the corrosion inhibition effect was the best.Compounded Na2MoO4,Na2B4O7 with PBTCA,the maximum corrosion inhibition rate could reach 90.40% on the condition of ?(PBTCA):?(Na2MoO4):?(Na2B4O7)=0.5:0.5:0.4.SEM diagram showed that the steel sheet have no corrosion in the compound system of both PBTCA and HPAA,verifying that the compound corrosion inhibition have a good inhibitive effects.Taking the HPAA as an example,the corrosion inhibition rate firstly increased as the standing time extending and then tended to be stable.The results indicated that extending the standing time would not weaken the corrosion effect and the HPAA compounding system was suitable for industrial applications.The RQ-222H?RQ-222DE?Germany Clariant SAS30 and CQ AL100 were selected as the main surfactants after the performance of cleaning rate,cloud point and antifoam properties were measured.Set cleaning rate as the response value to optimize surfactant materials,the predicted results showed that the optimum mass percentage of RQ-222DE?RQ-222H?SAS30 and CQ AL100 were 3.33%,1.33%,7.6% and 6.13%,respectively.The formula of metal cleaners was determined through repeated experiments by mixing HPAA compound corrosion inhibition with proper antifoaming agent and auxiliary agent.The cleaning rate of metal cleaners evaluated was 91.63% according to JB/T4323.2-1999,which was superior to that of the domestic nonphosphorus product(85.8%).The polarization curve results depicted that the corrosion inhibition rate of homemade cleaning agent(95.17%)was better than that of the domestic(86.29%).When extending the cleaning time,the EIS spectra revealed that impedance radius increased gradually.The result indicated that the corrosion inhibition of the cleaning agent was not weakened,but gradually tended to be stable.The phosphorus content in the formulation was 0.0029%.After cleaning the metal steels,the phosphorus content were 0.8 mg/L in aqueous solution.It was up to the integrated wastewater discharge standard GB8978-1996.