| Monosodium glutamate (MSG) wastewater is a kind of organic industrial wastewater in high concentration with high COD, SS and very low pH value. Also the wastewater contains many kinds of amino acids, and is rich in inorganic salts. Generally, the treatment process of monosodium glutamate wastewater is hard to meet the national industrial wastewater emission standards, and the treatment cost is very high. Studying the comprehensive utilization of monosodium glutamate wastewater is of great significance for the sustainable development of monosodium glutamate industry. The comprehensive utilization of monosodium glutamate wastewater has a variety of forms, such as the production of protein feed, biological pesticide and compound amino acid fertilizer. In this process, the proteins and amino acids in the waste water are recycled, which can realize the wastewater reuse and the high value of the wastes. Microelement amino acid chelate is obtained by the chelation reaction of amino acid and metal ions at a certain mole ratio. Microelement amino acid chelate is a new and efficient nutrient additive, having strong stability, high titer, and can be easily absorbed by organism. Considering the production cost, most of the microelement amino acid chelate treats keratin as raw material, which is conducive to the large-scale production and application of chelate. This paper prepared compound copper amino acid chelate and lanthanide compound amino acid chelate, using concentrated MSG wastewater to response with copper sulfate and lanthanum nitrate, respectively.Firstly, the preparation technology of compound copper amino acid chelate was studied in this paper. The dilution ratio of concentrated MSG wastewater, pH value, reaction temperature and reaction time were treated as influence factors to determine the appropriate synthesis conditions by single factor test and orthogonal test. The optimum synthesis conditions to obtain compound copper amino acid chelate were using50times diluents of MSG wastewater, adjusting the solution pH value of10.5, reacting in thermostat water bath at50℃for30minutes. This paper used organic solvent to make chelate precipitate and separate, and the chelating rate reached88.47%. Analysis methods such as UV, IR, DSC and TG were applied to characterize the composites chelate after purification treatment. It was found that glutamic acid, valine and tyrosine in concentrated MSG wastewater were all involved in the chelating reaction, and glutamic acid contributed most in synthetic reaction. Oxygen and nitrogen in amino acid molecules chelated with copper ions at the same time, forming stable coordination bond. Water molecules were involved in the coordination reaction. The content of amino acid in chelate was measured by automatic amino acid analyzer, which accounted for22.437%of the total sample. The content of glutamic acid reached12.264%.Secondly, the preparation technology of lanthanide compound amino acid chelate was studied in this essay. MSG diluents and lanthanum nitrate were the raw material. The optimum reaction conditions were determined by experiments. The lanthanide compound amino acid chelate was obtained by using30times diluents of MSG wastewater, adjusting the solution pH value of6, reacting in thermostat water bath at90℃for2.5hours. The chelate was separated and purified with acetone. The chelating rate was89.2%, measured by atomic absorption spectrophotometer. Analysis methods were applied to characterize the composites chelate after purification treatment. Results showed that glutamic acid and valine participated in the coordination reaction in the process of synthesis of chelate. And tyrosine did not react with lanthanum ion, free in solution. Carboxyl oxygen and amino nitrogen in amino acid molecules reacted lanthanum to form coordination bond at the same time. The water molecules also participated in the coordination reaction. Lanthanide compound amino acid chelate had thermal effect at117.84℃. There was an endothermic peak at172.96℃. The amino acids in chelate product started to break down, losing coordinated water. By means of analyzing the content of amino acid in lanthanide compound amino acid chelate, it was found that the content of amino acid in chelate accounted for25.518%of the total sample. The content of glutamic acid reached16.289%. This paper studied the preparation methods and properties of compound amino acid copper chelate and lanthanum compound amino acid chelate by concentrated MSG wastewater. This provides a new way for the synthesis of compound microelement amino acid chelates and broadens the research scope of the comprehensive utilization of MSG wastewater. It not only reduces the environmental pollution, and its products can be used as a micronutrient fertilizer, providing nutrients for the crops. There is a broad application prospects for compound microelement amino acid chelates. |
PDF Full Text Request