Synthesis And Corrosion Inhibition Performance Of Thiourea Base Rosin Imidazoline Quaternary Ammonium Salt

Acidification is commonly used in boiler cleaning process so that the boiler can achieve good cleaning effect,but acid can cause corrosion of metal equipment,which makes the boiler pickling process existing security risks.Therefore,it is necessary to study metal corrosion prevention in pickling process.At present,the effective method to prevent metal corrosion is to add corrosion inhibitor,because of its convenient operation,small dosage and high efficiency.Now with the continuous improvement in environmental protection requirements,pollution-free,non-toxic environment-friendly corrosion inhibitors are being sought and developed by scientists.Although the environmental friendly corrosion inhibitor has made great progress,there are problems of large industrial consumption and high cost.Therefore,in order to realize the popularization and application of industrialization,the environmental friendly corrosion inhibitor should work towards the direction of high efficiency and low cost.In this paper,with natural product rosin,diethylenetriamine,3-chlorinum-2-hydroxyl propane sulfonic acid sodium and thiourea as raw materials,through three steps reaction of dehydration condensation,quaternary ammonium and ammonia condensation synthesized thiourea base rosin imidazoline quaternary ammonium salt.In addition,the corrosion performance of target product for A3 carbon steel in the mass fraction of 15% hydrochloric acid solution was investigated,and the research contents were as follows:(1)Through solvent method,rosin imidazoline intermediate was synthesized with xylene as water carrying agent,aluminum oxide and magnesium chips as catalyst,rosin and divinyl three amine as raw material.The structure was characterized by means of FT-IR and 13 C NMR,and the resultshowed that the expected product was successfully synthesized.The optimum synthesis conditions for rosin conversion were discussed,and the results were as follows: the molar ratio of n(rosin):n(diethylenetriamine)was 1:1.6,cyclization temperature was 210?,amidation time was 4h,cyclization time was 5h,amidation temperature was 150? and the amount of water carrying agent was25% of the total mass of reactants,and the conversion rate of rosin could reach81.53% under this experimental condition.(2)Rosin imidazoline quaternary ammonium salt was synthesized with rosin imidazoline intermediate as raw material,3-chlorinum-2-hydroxyl propane sulfonic acid sodium as quaternary ammonium reagent,PEG600 as phase transferred catalyst,a mixture of isopropanol and water as solvent.The structure was characterized by means of FT-IR and 13 C NMR,and the result showed that the expected product was successfully synthesized.The optimum synthesis conditions for SN2 nucleophilic substitution reaction degree of rosin based imidazoline intermediate were discussed,and the results were as follows:reaction time was 5h;dosage of the catalyst was 14% of the amount of substance of rosin based imidazoline intermediates;quaternary ammonium temperature was 123?;the molar ratio of n(3-chlorinum-2-hydroxyl propane sulfonic acid sodium):n(rosin based imidazoline intermediates)was 0.89:1;the mass ratio of m(water):m(isopropanol)was 2.14:1.Under the above-mentioned conditions,SN2 nucleophilic substitution degree of rosin based imidazoline intermediates could reach maximum.(3)With rosin imidazoline quaternary ammonium salt and thiourea as raw material,n-octanol as stabilizer,water as solvent,thiourea base rosin imidazoline quaternary ammonium salt was synthesized by condensation reaction.The structure was characterized by means of FT-IR and 13 C NMR,and the result showed that the expected product was successfully synthesized.The optimum synthesis conditions for productivity of thiourea base rosin imidazoline quaternary ammonium salt were discussed,and the results were as follows: the molar ratio of n(thiourea):n(quaternary ammonium salt)was 1.5:1;reaction temperature was 130?;reaction time was 3h;dosage of the solvent was 60% of the total mass of reactants;Under the above-mentioned conditions,the yield of product could reach 61.49%.(4)The thiourea base rosin imidazoline quaternary ammonium salt was used in the mass fraction of 15% hydrochloric acid solution to corrosion performance test.The corrosion inhibition performance of A3 steel under different corrosion conditions was studied by means of weight loss,polarization curves and electrochemical impedance spectroscopy.The results indicated that the corrosion inhibition efficiency of the self-made corrosion inhibitor increased first and then decreased with the increase of the mass fraction of corrosion inhibitor,at 303 K,the corrosion inhibition efficiency was the highest when the mass fraction of corrosion inhibitor was 0.4%,and the value was 90.81%.The inhibition efficiency decreased with the increase of immersion time,but the rate of decline slowed,indicating that it had a certain effect;The corrosion inhibition efficiency decreased with the increase of temperature,indicating that the corrosion inhibitor was not suitable for high temperature;The self-made corrosion inhibitor could effectively inhibit the corrosion of hydrochloric acid,and the self-made corrosion inhibitor was a mixed type inhibitor which was mainly controlled by the cathode.(5)The adsorption film of the self-made corrosion inhibitor on the surface of A3 steel was characterized by environmental scanning electron microscope(ESEM),atomic force microscopy(AFM),contact angle(CA)and X ray photoelectron spectroscopy(XPS),and it was confirmed that the target corrosion inhibitor could form corrosion inhibitor adsorption film on the surface of carbon steel.(6)A preliminary study on the corrosion inhibition mechanism of the self-made corrosion inhibitor was carried out,and the study found that: in the process of corrosion inhibition,the self-made corrosion inhibitor was adsorbed on the surface of carbon steel by physical and chemical adsorption.