Study On Synthesis And Properties Of Ricinoleic Acid-based Surfactant

Ricinoleic acid is a rich renewable resource and a widely used chemical raw material.As an important green raw material of surfactants,ricinoleic acid-based surfactants can be obtained by modification of ricinoleic acid,which not only increases the added value of ricinoleic acid,but also promotes the further processing of castor oil and the development of its industrial chain.In this study,ricinoleic acid-based surfactant was synthesized by esterification,epoxidation,ring-opening and sulfonation with ricinoleic acid as raw material.The structure and properties of the synthesized surfactant were characterized and tested.The main experiments and results are as follows:1.Synthesis of ricinoleic acid methyl ester?RAME?: Ricinoleic acid was esterified with methanol using p-toluenesulfonic acid as the catalyst.The effects of various esterification parameters including the methanol/oil molar ratio,reaction temperature,catalyst dosage,and reaction time were investigated by one-factor-at-a-time experiments.The optimum conditions for esterification were obtained at the a methanol/oil molar ratio of 12:1,reaction temperature of 80 °C,catalyst dosage of 1.0 wt%,and reaction time of 2.5 h.The maximum conversion of esterification reached 95.63%.The structure of the ricinoleic acid methyl ester was characterized by Fourier transform infrared?FTIR?spectroscopy and gas chromatography-mass spectrometry?GC-MS?.2.Synthesis of ricinoleic acid methyl ester epoxide?ERAME?: First,synthesis of the phase-transfer catalyst [?-C₅H₅N?CH₂?₁₅CH₃]₃[PW₄O₁₆].Then,the structure of the [?-C₅H₅N?CH₂?₁₅CH₃]₃[PW₄O₁₆] were characterized by elemental analysis,energy dispersive X-ray spectroscopy?EDX?,FTIR,31 P MAS NMR spectra,and Raman spectrometer.The Box-Behnken design combined with RSM were used to optimize the reaction conditions and better understand the relationships between the reaction variables?the molar ratio of H2O2 to C=C bonds,catalyst dosage,reaction time and reaction temperature?and the response?conversion?.The optimum conditions for epoxidation of RAME were obtained at the a H2O2/C=C molar ratio of 1.93,catalyst dosage of 3.11 wt%,reaction temperature of 52 °C,and reaction time of 75 min.Under these conditions,a high conversion of?94.46±0.30?% was observed,which is in agreement with the predicted results?94.52%?.The epoxidation of RAME by hydrogen peroxide and the [?-C₅H₅N?CH₂?₁₅CH₃]₃[PW₄O₁₆] phase-transfer catalyst followed pseudo-first order kinetics with an activation energy?Ea?of approximately 21.6 k J/mol.In addition,the reaction process is a mass-transfer control process.3.Synthesis of ricinoleic acid methyl ester hydroxy monomethyl-PEG 350-ether?ERAME-Me PEG?: Epoxide ring of ricinoleic acid methyl ester epoxide was opened with monomethylated PEG-350 and boron trifluoride to obtain ERAME-Me PEG.The effects of various ring-opening parameters including the reaction temperature,a ratio of raw materials,catalyst dosage,and reaction time were investigated by one-factor-at-a-time experiments.The optimum conditions for ring-opening reaction were obtained at the reaction temperature of 65 °C,a Me PEG-350/ERAME molar ratio of 1.5:1,catalyst dosage of 0.7 wt%,and reaction time of 2.5 h.The structure of the ERAME-Me PEG was characterized by FTIR.4.Synthesis of branched chain methyl ricinoleate sulfate?ERAMES-Me PEG?: ERAME-Me PEG was sulfonated by chlorosulfonic.Then,sodium hydroxide was added to neutralize the reaction mixture.The product was obtained by vacuum distillation,washing,and extraction.The structure of the ERAMES-Me PEG was characterized by FTIR.5.The physicochemical performances of the product: The product obtained in this study was a mixed system.The physicochemical properties of the product such as surface tension,critical micelle concentration,HLB value,emulsifying property,foam performance,wetting property,solubility,calcium tolerance and detergency property were measured.The results showed that the product exhibited superior surface active properties,strong Ca2+ tolerance,better wetting and emulsion stability,good detergency,and lower foam performance.The results indicating that the ERAMES-Me PEG is a kind of low-foaming surfactant with good detergency performance.It can be applied to low-foam cleaning and washing.