Tuesday, June 4, 2019
Anti-hygroscopicity of Ammonium Nitrate (AN)
Anti-hygroscopicity of Ammonium Nit swan (AN)Anti-hygroscopicity of Ammonium Nitrate (AN) surface by surfactant materials Baha Eldien Ismail Abd Allah Elzaki1,2, Zhang Yue Jun2AbstractThe ammonium nitrate (AN) particles were coat by surfactant materials, utilise precipitation coat method. The hygroscopicity of AN coat and AN without applications programme (used as control) were tested, and the samples of AN coat by surfactant materials, and were characterized by Fourier trans tenor infrared (FTIR), and surface morphology of samples were observed by scanning electron microscopy (SEM). Mass grinding of cover storey, and wane of preoccupation rate were calculated. The results indicate that cetylalcohol promising coating surfactant material for AN among the materials tested, namely, stearic red-hot, octadecylamine, alcohol, palmitic acid, and lauric acid. The push-down stack friction of coating layer, and lower of concentration rate of AN coated by cetylalcohol were 0.98%, and 28.28%, respectively. The idea and approach presented in this paper have potential to made hydrophobic surface on the surface of AN particles to become anti-hygroscopicity. and also used in other energetic materials to reduce sensitivity.Keywords Ammonium nitrate (AN) Hygroscopicity Anti-hygroscopicity Surfactant materials, Precipitation coatingIntroductionAmmonium nitrate (AN) (NH4NO3), is produced by the reaction of anhydrous ammonia gas(NH3), and aqueous nitric acid (HNO3) 1, 2. Which is present as the major comp adeptnt in most industrial explosives, such as amatol, ANFO, and also used in fertilizers3-6. AN is of considerable interest as potential eco- friend oxidizing in solid propellants2, 7-9. The risks of used oxidizer ammonium perchlorate (AP) in solid propellants was realized with the hydrogen chloride (HCL) with piss form hydrochloric acid which produces highly toxic smoke, this cause significant damage to the environment, due this is reason replaced by AN as oxidiz er in solid propellants10, 11. It is one of the cheapest, and easily available oxidizer. However, its use in large rocket motors and as solid propellants is restricted due to the hygroscopicity12. The molecules of AN are polar it easy absorb the polar moisture from the surrounding, leads to dissolved AN13.R.S. Damse used waterproofing materials mineral jelly and other to reduce hygroscopicity of AN14. Kun-Lun Hu et.at., used octadecane amine, resin wax and etc as coating agent for coating AN particles (20- 04 meshes), used melting process. Zhang et.al. used silane coupling agent KH792 for coating AN particles (50-75 meshes), used surface chemical coating15. The present work deals with a new approach to form the hydrophobic layer on the surface AN particles, by precipitation surfactant materials on the surface of AN molecules. to increase the decline of intentness rate, and decrease big bucks friction of coating layer, in the conditions of absorption rate measurement, the size of particles of AN are 70-140 meshes, temperature is 35 , and the relative humidness is 67.5%.Materials and MethodMaterials AN supplied by Kecheng fine chemical CO. Ltd (+99.0% Shanghai, China ), trichloromethane (+99.0%, Shanghai Ling Feng Chemical Reagent Co. LTD , China), and Cyclohexane (99.5% Industrial development zone, Chengdu, China). Surfactant materials used AlcoholC18, Stearic Acid, Cetylalcohol, Palmic acid, and Lauric acid (99.0% Chengdu Kelong chemical Reagent , China), Octadecylamine (99%Tianjin Fine Chemical Research Institute).Method. 6g of AN coated by 2g of surfactant materials in 15ml chloroform and 15ml cyclohexane. The reaction with stirring at 60oC about 2 h stopped heat, let the reaction contents cooling, the temperature change magnitude to 35oC in 5 h, at this stage the water of bath heating was changed, and when the temperature reach to 30oC, the end of reaction. AN coated was filtered by vacuum filter, and drying at 50oC, after drying 5g of AN coated tested at35, humidity is 67.5% absorption rate test 24hMeasurement of absorption rate. The samples were weighed 5g in 3060 mm weighing bottle without cap, placed in a desiccator containing saturated solution of strontium chloride (relative humidity 68%) of the absorbent 35 24 h, absorption rate of humidity HR was measured by the following equationWhere HR- absorption rate,%M0 absorbent sample before mass, gM mass of the sample after the moisture, g.Mass fraction of coating layer test. Mass friction of coating layer was determined by wetted the filtration paper, dried 1h in an oven weighting (WB). A sample of AN coated after absorption humidity was dissolved in water, and filtered through a tapered funnel, the filter paper was washed by water several times, and placed in an oven 1h, weighing again(WA). The mass fraction of the coating layer was calculated by the following equationWhere W- mass fraction of coating layer,%.M0 mass of sample before absorbed moisture, g.M1 mass of coating lay er, g= WA WBDecline of moisture absorption rate was calculated by following equationWhere A- decline of moisture absorption rate,%.HR1 absorption rate of AN sample,%.HR2 absorption rate of coated AN sample,%.Characterization. Spectra of the samples were recorded on a Fourier transform infrared (FTIR) spectrophotometer (Thermo Scientific Nicolet I S10, Thermo Fisher USA) by using KBr pellets. Surfaces modified were observed for their morphological study under scanning electron microscopy (SEM) (JEOL JSM 6380LV, Japan).Results and DiscussionThe absorption rate , mass friction of coating layer and decline of AN coated by different kind of surfactant materials are presented in table 1, in this table used cetylalcohol, alcohol C18, octadecylamine, stearic acid, Palmitic acid, and lauric acid to coated AN , the data from hygroscopicity test clearly indicate that cetylalcohol is the outdo surfactant materials to coating AN lower mass friction of coating layer was 0.98%, and high decline o f absorption rate was 28.28%. Stearic acid and octadecylamine were found second and third best, respectively, while alcohol C18, Palmitic acid and lauric acid followed the order sequentially (table 1). It is seen that when change the concentration of solvents, the decline of absorption rate of AN coated by cetylalcohol, stearic acid, and octadecylamine were slightly decreased, and the decline of AN coated by alcohol C18, Palmitic acid, and Lauric acid were slightly increase (table 2). Also the best coating surfactant materials is cetylalcohol, has highly decline was 24.09%, and lower mass friction coating layer was 0.89%.Table (1) 2g of surfactant materials, 6 g of AN, 15 mL of chloroform + 15 mL cyclohexane HR measurement conditions (70 mesh 140 mesh or more T = 35 humidity is 67.5%)NoSurfactants submerging Rate %Mass friction of coating layer%Decline%1Cetylalcohol5.850.9828.282Stearic acid6.451.2019.893Octadecylamine7.711.1819.624Alcohol C186.420.3913.135Palmitic acid126.96.36.199 6Lauric acid6.240.873.79Table (2) 2g of surfactant materials, 6 g of AN, 30 mL of chloroform, at 60oC, HR measurement conditions (70 mesh 140 mesh or more T = 35 humidity is 67.5%).No.surfactantsHygroscopicity(HR) %Mass friction of coating layer%Decline%1Cetylalcohol5.610.8924.092Stearic acid6.392.5613.533Octadecylamine6.422.2313.134Alcohol C186.121.4817.195Palmitic acid6.210.4615.976Lauric acid6.170.4816.51In figure 1 observed the government issue of time on hygroscopicity of AN coated by surfactant materials (cetylalcohol (a), alcohol C18(b), and stearic acid(c)) and AN without coating (d) were tested in the hygroscopicity test conditions were size of particles of AN were 70-140 meshes, temperature was 35 , and the relative humidity was 67.5%. The absorption rate directly proportionate with time. The lowest regression was obtained from AN coated by cetylalcohol (a), and the highest regression was obtained from AN without coating(d). The absorption rate of AN coated by cetylalco hol is significant than reported in Previous studies16, 17. dactyl (1) effect of time on the hygroscopicity ( submergence rate) of AN coated by cetylalcohol (a), alcohol C18 (b), stearic acid (c), and AN without coated (d)The influence of the amount of surfactant materials on the decline of absorption rate and mass friction of coating layer were studies on the AN coated by different amounts of cetylalcohol, (0.5, 1.0 1.5, 2.0. and 2.5 g), the regression of decline of absorption rate was increased to high protect at 2.0 g of cetylalcohol, then decreased at 2.5g of cetylalcohol, this is due to polar head of surfactant not precipitated on the surface of AN particles, and this causes hydrophilic surface leads to increased hygroscopicity, thus, decreased decline of absorption rate. The mass friction of coating layer directly proportional with the amount of surfactant materials(figure 2). This results significant than results reported in literature18, 19.Figure (2) effect of amount of su rfactants materials on the absorption rate and mass friction of coating layer.In the measurement of absorption rate used 3060 mm weighing bottle without cap, the effect of amount of sample in this bottle was studied, the weight of samples were tested 10, 15, 20, and 25 g. The regression of absorption rate is inversely proportional to the weight of the sample, in the both AN coated by cetylalcohol, and AN without coating (figure 3).Figure (3) effect of weight of samples on the absorption rateCharacterizationFTIR Absorption Spectra. The surface modified of AN and AN without modified were monitored by using FTIR measurement as depicted in figure 4. Alkanes C-H stretch peak around 3000-2850 cm-1was appeared after coating AN by cetylalcohol (a), higher than AN by alcohol C18, and steric acid in (b) and (d), respectively. Alkanes no appeared in AN without coating in (c). Hence, alkenes non polar has effected on hygroscopicity.Figure 4 FTIR spectra of the ammonium nitrate coated by cetyla lcohol (a) ammonium nitrate coated by alcohol C18 (b) ammonium nitrate without coating (c) ammonium nitrate coated by steric acid (d). see Electron Microscopy. The surface morphology in figure (5) presented the AN coated by cetylalcohol has a clear difference in cultivate particles and the surface smooth than, AN coated by stearic acid (figure 6), octadecylamine(figure 7) , and alcohol C18(figure 8), and ammonium nitrate without coating were observed in figure 9.Figure 5. examine electron microscope of surface modification of AN coated by cetylalcohol.The scale bar represents, degree centigradem. Electron micrographs.Figure 6. Scanning electron microscope of surface modification of AN coated by stearic acid.The scale bar represents, 100m. Electron micrographs.Figure 7. Scanning electron microscope of surface modification of AN coated by Octadecylamine.The scale bar represents, 100m. Electron micrographs.Figure 8. Scanning electron microscope of surface modification of AN coated by alcohol C18.The scale bar represents, 100m. Electron micrographs.Figure 9. Scanning electron microscope of surface of AN without coating.The scale bar represents, 100m. Electron micrographs. Conclusions.In this study the cetylalcohol has been found to be the best surfactant materials for coating ammonium nitrate among the materials tested. The mass friction of coating layer of cetylalcohol was found 0.98%, and decline 28.28%, at the hygroscopicity test conditions temperature 30oC, 68% RH, and time 24h. the optimum amount of surfactant material 2g to coating 6g Ammonium nitrate. The samples were characterized by using FTIR spectra, and SEM. The weight of samples in hygroscopicity test effected significantly on the hygroscopicity of AN.