Synthesis And Characterization Of Cobalt Carboxylates Environmental Sciences Essay

implication And Characterization Of conscientious objector Carboxylates Environmental Sciences EssayPlastics atomic number 18 commonly added with certain additives for exploitation its better characteristics. Recent decades, some kinds of additives which are known as prodegradant additives are being developed for plastics film. Prodegradant additives lay virtu all(prenominal)y result in accelerating plastics abasement. It is important to develop prodegradant additives since plastic waste is viewed as a serious oecumenic environmental and health concern as its character of being non-degradable. legion(predicate) pro-degradant additives, composed of transmetal-organic irate flavors, boast been investigated in many researches as photodegradable additives for plastics. Cobalt carboxylates, namely atomic number 27 laurate, degree centigrade monoxide gas palmitate, conscientious objector stearate, are kinds of which lead been applied for LDPE films. In the previous method, carbon monoxide gas carboxylates were synthesized by reacting sodium carboxylates and carbon monoxide gas acetate. This paper reports a raw(a) method of cobalt carboxylates synthesis. The new method involve reaction between molten carboxylic acid with sodium hydroxide theme to produce sodium carboxylate, and continued by reacting sodium carboxylate with chloride salt of cobalt. First reaction conducted at 80C and under(a) perfect upheaval. Second reaction took address headspring in the slump concentration of cobalt chloride, about 0.2 M or less and temperature 80C. Cobalt carboxylates (cobalt laurate, cobalt palmitate, cobalt stearate) densities are 0.615, 0.391, 0.364 g/cm3 respectively. Their melting signals are 107.83, 109.10, 114.40 C respectively, obtained by DSC test. thermogravimetric Analyzer (TGA) test wee been done on cobalt carboxylates to investigate their thermal stabilities. All cobalt carboxylates start to degrade all over 300C, as shown in TGA test resul t. TGA studies indicate that cobalt carboxylates have stability at compounding and film b crusheding/casting temperature of polythene, 180-200C.Keywords Prodegradant additives, cobalt carboxylates, characteristics1. IntroductionPlastics employment systematically increases, thus, excessively plastics waste amount grows. People rely to plastics in everyday activities, such as jugs, clothes, computer, etc 1,2.Recently, the usage of plastics increases significantly. USs plastics production in 2000 amounted to more 45,000,000 metric tons 2. Total resin consumption in Malaysia increased by 8% from 1.6 million MT in 2004 to 1.72 million MT in 2005, of which about 65% were polyolefins (PE PP) 3. The municipal solid state waste stream in the U.S. totals nearly 160 metric tons per year and consists of about 7-11% by weight of post-consumer plastics 4.Plastics is now being viewed as a serious worldwide environmental and health concern, especially for disposable application such as carrier a nd garbage bags 2. Its character of being non-degradable, is resulting in river pollution, choking in landfill 4. The growing environmental concern has made plastics a target of much unfavorable judgment due to their lack of degradability 5.Therefore degradable plastics will be important issue to reduce plastics waste amount. Many researches have been done to obtain methods which can improve degradability of plastics.Some methods are used to accelerate the abasement process are the addition of transition metal pro-oxidants or carbon monoxide polymer, both of which are intentional to catalyse photodegradation and thermal degradation 6.The studies on utilizations of some additives have been performed by several researchers to obtain photodegradable plastics. The burden of a series transition metal (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) stearates on the photodegradation of a tall-density polyethylene have been examined. The role of metal-looking compounds on the photodegradation of polyethylene has been extensively studied by several authors 7.The marrow of cobalt stearate on quicken aging of LDPE has been studied. Cobalt stearate has been proven to have significant effect on accelerated aging of LDPE 8. The effect of cobalt carboxylates namely cobalt laurate, cobalt palmitate, cobalt stearate, on the photo-oxidative degradation of low density polyethylene also have been investigated 9. Cobalt carboxylates have been synthesized through restate decomposition by reacting sodium carboxylates and cobalt acetate 9,10.This paper report the study of new synthesis method of cobalt carboxyates through double decomposition method by reacting sodium carboxylates and cobalt chloride. This paper also attempt to investigate characteristics of cobalt carboxylates.2. Experimental2.1 MaterialsCobalt chloride hexahydrate (Fluka), sodium hydroxide, lauric acid, palmitic acid, and stearic acid (Merck) were used without any treatments. Deionized water was used for all processes .2.2 Synthesis of cobalt carboxylatesCobalt carboxylates, namely cobalt laurate, cobalt palmitate, and cobalt stearate, were synthesized through two travel of reactions. First step, carboxylic acids (lauric acid, palmitic acid, and stearic acid) were reacted with sodium hydroxide to produce sodium carboxylates (sodium laurate, sodium palmitate, and sodium stearate).The entropy gear step, sodium carboxylates (sodium laurate, sodium palmitate, and sodium stearate) were reacted with cobalt chloride to produce cobalt carboxylates (cobalt laurate, cobalt palmitate, and cobalt stearate) in solid phase .The solids were filtered and washed with hot water to separate sodium chloride. Finally, the solids were dried in the oven at 60 C for 2 hours.2.3 Characterization of cobalt carboxylatesThe characterization comprises density, melting point, and degradation temperature. run points were investigated using differential coefficient Scanning Calorimeter (DSC) Q1000 from TA Instruments, in N 2 atmosphere, in temperature range 30-200 C, at heat rate 10 C/min. Evaluation of degradation temperatures were done using Thermogravimetric Analyzer (TGA) Q500 from TA Instruments, in N2 atmosphere, ramp method, heating rate 20 C/min, final temperature 1000 C.3. Result and Discussion3.1 Synthesis of cobalt carboxylatesSynthesis of cobalt carboxylates comprises two steps of reactions. The first step, producing sodium carboxylates through reaction below.These reactions took place in fluidity phase at 80 C. Carboxylic acids were melted and added gradually with sodium hydroxide 0.25 M under agitation for one hour. The amount of carboxylic acids and sodium hydroxide were reacted in stoichiometric ratio. Perfect agitation was needed to reach a complete reaction.The second step, synthesis of cobalt carboxylates, was conducted by adding cobalt chloride hexahydrate solution 0.20 M into the product of first step reaction which contain sodium carboxylates. Cobalt chloride solution was added gradually. The reaction temperature was maintained at 80 C, with continuous stirring.The second reaction could be written as come throughIn the second reaction, cobalt carboxylates, which were produced in solid phase, would form suspension and became hard to be stirred. The low concentration of cobalt chloride was favored since reaction would take place well in low concentration. The low concentration of cobalt carboxylates would produce few solids of cobalt carboxylates. It mean that mixing process would run well and complete reaction could be reached.3.2 Characterization of cobalt carboxylatesDensityDensities of cobalt carboxylates can be seen in board 1. All of cobalt carboxylates are in the form of powder and have low density.Melting PointTests have been done using Differential Scanning Calorimeters (DSC) to determine melting point of cobalt carboxylates. The DSC test results can be seen in Fig. 1, Fig. 2, and Fig. 3.The melting point of cobalt laurate, cobalt palmitate, and cobalt stearate was dogged from the peak of endothermic melting transition. Melting points of cobalt carboxylates can be summarized as listed in Table 2 below.There are two endothermic peaks in Fig. 1 and Fig. 2. Two endothermic peaks are sometimes found in DSC test result. First peak indicate unstable melting process. The second peak represent stable melting process 11.Melting points of cobalt carboxylates increase with increasing carbon chain continuance of carboxylates. Melting point of cobalt stearate which has 18 C is higher than melting point of cobalt palmitate which has 16 C. Melting point of cobalt palmitate is higher than melting point of cobalt laurate which has 12 C.Thermal stabilityThermal stability was investigated using Thermogravimetric Analyzers (TGA). Degradation temperature (initial and final temperature of degradation) was determined from high decrease of weight during heating. It was shown by steep slope of the curve in TGA test result. Cobalt carboxylates il logical more than 80% of their weight during degradation process. The final weight remained was around 10 % of initial weight.The degradation temperature increase from cobalt laurate, cobalt palmitate, and cobalt stearate respectively. All of cobalt carboxylates start to degrade at temperature over 300 C.It means, cobalt carboxylates have good thermal stability since the temperature of blending/compounding of polyethylene is 180-200 C. Cobalt carboxylates will not degrade at temperature of compounding and film blowing/casting of polyethylene.4. ConclusionSynthesis of cobalt carboxylates could be conducted through reaction of sodium carboxylates and cobalt chloride in liquid phase. The melting point of cobalt carboxylates increased with increasing the length of carbon chain. Thermal stability also increased with increasing the length of carbon chain, as indicated by temperature of degradation. Cobalt carboxylates also had thermal stability at temperature of polyethylene processing.