Study On Synthesis,Properties And Applications Of Fatty Alcohol Ether Quaternary Ammonium Salt

Surface active agents exhibit excellent surface activity and application performance due to their special interface phenomena and self-assembly behavior.Currently,surfactants have been widely used in daily chemical industry,petroleum,metal corrosion protection,textile printing and dyeing,as well as biomedicine and other fields.Cationic surfactants exhibit special properties such as bactericidal,adsorption and antistatic due to the carried cationic charge.As a nonionic cationic surfactant,fatty alcohol ether quaternary ammonium salt exhibits superior hydrophilicity and adsorption performance due to the modification of hydroxyl and ether groups on the molecular structure,thus having broad application prospects.Existing fatty alcohol ether quaternary ammonium salts have good hydrophilicity,but their complex molecular structure requires complex synthesis processes and harsh reaction conditions.In addition,it is not conducive to environmental protection when used in large quantities.Therefore,simplifying the molecular structure of fatty alcohol ether quaternary ammonium salt is beneficial to shorten the synthesis steps and promote industrial production.Furthermore,the improvement of application performance can reduce the dosage and reduce costs.This study presents a novel synthesis of a fatty alcohol ether quaternary ammonium salt that exhibits exceptional hydrophilicity and adsorption properties thanks to its precisely controlled molecular architecture.Subsequent investigations on this compound’s surface properties and application performance were conducted,culminating in an exploration of its potential application as an acid pickling corrosion inhibitor.The main research contents are as follows:（1）Synthesis and characterization:Two fatty alcohol ether quaternary ammonium salts（DDBGA and HDBGA）with different carbon chain lengths were synthesized by a two-step method.Taking yield and conversion rate of tertiary amine as indexes,the influence of different factors on the reaction was explored by single factor and orthogonal experiments,and the optimal reaction conditions were determined.Under the optimal reaction conditions,the yield of intermediate butanoxy chlorinated glycerol ether（BCGE）is 93.36%,and the conversion of tertiary amine was 99.45%.Fourier Transform Infrared spectroscopy（FT-IR）,Nuclear magnetic resonance（¹H NMR）and mass spectroscopy（MS）proved that the intermediates and products were accurately synthesized.（2）Performance test:The surface activity,micellar thermodynamic properties and micropolarity of DDBGA and HDBGA molecules were studied by surface tension method,electrical conductivity method and steady-state fluorescence probe method,and the aggregation behavior of DDBGA and HDBGA molecules in aqueous solution was explored according to micellar aggregation number(N_agg)and mean hydrodynamic radius（R_h）.The results show that at 298 K,the critical micelle concentrations（cmc）of DDBGA and HDBGA were 3.98×10^-3mol·L^-1 and 3.74×10^-4 mol·L^-1,respectively,and the surface tension at critical micelle concentrations(γ_cmc)were 30.16 m N·m^-1 and 31.28 m N·m^-1,respectively.With the increase of hydrophobic chain length,the molecules tend to aggregate into micelles,which reduces the cmc.The coining of long carbon chains increasedγ_cmc gradually.With the increase of temperature,the water structure around the alkyl chain is destroyed,which is not conducive to the formation of micelle and the cmc increases.The cmc values measured by the conductivity method and the steady-state fluorescence probe method were basically consistent with those measured by the surface tension method.In addition,the thermodynamic parameters of the micellization of fatty alcohol ether quaternary ammonium salts indicate that the micellization process is a spontaneous exothermic process.When the concentration reaches cmc,the N_agg values of DDBGA and HDBGA are 7.48 and 8.87,respectively.At a higher concentration,it is easy to form spherical micelles in aqueous solution.The application properties of the fatty alcohol ether quaternary ammonium salts were tested,and the results showed that DDBGA and HDBGA have average foam stability,but good wetting,emulsification and antistatic properties,and does not cause damage to the mechanical properties of the fabric.（3）Corrosion inhibition performance and application in acid pickling inhibitor formulation:The corrosion inhibition performances of HDBGA on Q235 steel in 1 M HCl and 1 M HCl+3.5 wt%Na Cl solutions were studied.The highest corrosion inhibition efficiency was achieved at a concentration close to cmc.It reached 98.52%and 99.06%in 1 M HCl and 1 M HCl+3.5wt%Na Cl solutions,respectively.The corrosion rate of carbon steel increases with increasing temperature,but the inhibition efficiency is highest at 308 K.The Langmuir isotherm model showed that HDBGA adsorbed on the surface of carbon steel mainly depended on chemical forces.Electrochemical study found that the inhibitor behaves as a cathode and anode mixed type of inhibitor.Surface analysis shows that HDBGA molecules can effectively adsorb on the surface of carbon steel to form a protective film to inhibit corrosion.Moreover,HDBGA was used as the main inhibitor in the pickling inhibitor formulation,and compared with the formulation of dodecyl trimethyl ammonium chloride（DTAC）and 2-Mercaptobenzothiazole（MBT）as the main inhibitor.Through static weight loss method,electrochemical method and surface morphology analysis,it was proved that the pickling inhibitor formulation containing HDBGA could effectively inhibit corrosion,and its fog inhibition ratio and degreasing properties are better than those containing DTAC and MBT.