Sintesis dan karakterisasi 9,10-Dihidroksistearat-Dietanolamida sebagai surfaktan nonionik dari jelantah minyak sawit

MURININGSIH, Catur Endang Sukti, Dr. Tutik Dwi Wahyuningsih

2009 | Tesis | S2 Ilmu Kimia

Telah dilakukan sintesis dan karakterisasi senyawa 9,10-dihidroksistearat-dietanolamida dari jelantah minyak sawit sebagai surfaktan nonionik. Tahapan sintesis melibatkan reaksi transesterifikasi, hidrolisis, oksidasi dengan KMnO4 dalam suasana basa dan amidasi asam 9,10-dihidroksistearat dengan dietanolamina. Semua produk reaksi dianalisis dengan spektometer IR dan GC-MS dengan metode sililasi. Uji karakterisasi surfaktan dilakukan dengan pengukuran tegangan muka menggunakan metode kenaikan pipa kapiler, penentuan KKM (Konsentrasi Kritis Misel) menggunakan metode turbidimetri, pengukuran kestabilan busa, penentuan kestabilan emulsi dan indeks emulsi serta penentuan nilai HLB (Hydrophilic Lypophilic Balance) dengan metode Griffin aturan Bancroft. Reaksi transesterifikasi jelantah minyak sawit menghasilkan campuran metil ester dengan rendemen 82,94 %. Reaksi hidrolisis campuran metil ester menghasilkan campuran asam-asam lemaknya dengan rendemen 88,46 %. Reaksi oksidasi campuran asam-asam lemak bebas menghasilkan serbuk putih asam 9,10-dihidroksistearat dengan titik leleh 127-128 ºC dan persen konversi 42,99 %. Reaksi amidasi asam 9,10-dihidroksistearat dan dietanolamina menghasilkan senyawa 9,10-dihidroksistearat-dietanolamida dengan rendemen 49,79 %. Hasil uji karakterisasi menunjukkan bahwa senyawa alkanolamida hasil sintesis mampu menurunkan tegangan muka etanol dari 21,70 menjadi 16,09 dyne/cm dengan nilai KKM terbentuk saat konsentrasi larutan 1,4 g/L, busa yang terbentuk mampu stabil hingga 1,5 jam, indeks emulsi campuran air-surfaktan-minyak kedelai sebesar 26,67 % sedangkan indeks emulsi campuran air-surfaktan-bensin sebesar 10,00 %. Pembentukan emulsi pada kedua campuran stabil hingga 4 hari. Nilai HLB surfaktan hasil sintesis sebesar 14,02 % bersifat sebagai larutan pembersih dan dapat dimanfaatkan sebagai pelarut.

Synthesis and characterization of 9,10-dihydroxystearic-diethanolamide from used frying palm oil as nonionic surfactant has been carried out. The synthesis was performed via several steps of reaction, i.e. : transesterification, hydrolysis, oxidation with KMnO4 in basic condition and amidation of 9,10-dihydroxystearic acid with diethanolamine. Structure elucidation of all products was carried out by IR and GC-MS with silylation method. Characterization of surfactans was performed by surface tension measurement (capillary rise method), determination of CMC (Critical Micelle Concentration) with turbidity method and calculation of HLB (Hydrophilic-Lypophilic Balance) value with Griffin and Bancroft rule. Transesterification of used frying palm oil produced mixture of methyl esters with the total yield of 82.94 %. Hydrolysis of mixture of methyl esters gave mixture of fatty acids in 88.46 % total yield. Oxidation reaction of fatty acid yielded white powder of 9,10-dihydroxystearic acid with m.p. 127-128 ºC and the convertion percents is 42.99 % yield. Amidation reaction of 9,10-dihydroxystearic acid with diethanolamine gave of 9,10-dihydroxystearic-diethanolamide in 49.79 % yield. Characterization as nonionic surfactant showed that the alkanolamide could reduce the surface tension of ethanol from 21.70 to 16.09 dyne/cm with CMC at 1.4 g/L, foam was stable until 1.5 hours of observed time, water-surfactant-soybean oil system has 26.67 % emulsion index, while water-surfactant-gasoline system has 10.00 % emulsion index. Stability of both emulsions has been observed until 4 days. Furthermore, HLB value of surfactant is 14.02 % with have characteristic as a cleaning agent and can be used as solvent.

Kata Kunci : Asam 9,10,dihidroksistearat,Srfatan nonionik,Amidasi,Dietanilamina, 9,10-dihydroxystearic acid, nonionic surfactant, amidation, diethanolamine