The Synthesis Technology And Properties Of Polyaspartic Acid

Polyaspartic acid is a kind of environmental material with excellent biocompatibity,which is biodegradable and environmental friendly.It has been widely used in cosmetics,industrial water treatment,medicine,agriculture and other industries because of its superior performance.In this paper,we adopted the method of solid melting to synthesis the intermediate product polysuccinimide using maleic anhydride and ammonia as raw materials,the process was divided into two steps,and then polyaspartic acid was obtained by hydrolysis of polysuccinimide under the condition of alkaline.The product was characterized by infrared spectroscopic analysis and gel chromatography,at the same time,the effects of various factors,such as molar ratio of raw materials,reaction temperature,reaction time,pH value,hydrolysis temperature and hydrolysis time on the molecular weight and yield of the polymerizate were also studied,the synthetic process of polyaspartic acid had been optimized.Then,the scale inhibition performance of polyaspartic acid on CaCO3 was explored by static scale inhibition method.The results showed that the polyaspartic acid obtained was controllable molecular weight and higher productivity by improving and optimizing the synthesis process,and the molecular weight was between 5000 and 8000.Polyaspartic acid has excellent chelation and dispersion properties,which can chelate a variety of metal cations,but in practical application,there are some problems such as difficulty in solid-liquid separation,difficult in recovery and so on.In this paper,combination of both montmorillonite and polyaspartic acid had been investigated as a novel adsorbent for Cu²⁺,Zn²⁺ and Ni²⁺ ions adsorption from aqueous solution named polyaspartic acid/montmorillonite composite.Modern analytical techniques of FTIR,XRD and TG were used to describe the characteristics of polyaspartic acid/montmorillonite composite,the results showed that we successfully synthesized the composite.In this work,we studied some effects of absorbent amount,pH value,initial concentration and temperature on the single system of Cu²⁺,Zn²⁺ and Ni²⁺ ions adsorption by polyaspartic acid/montmorillonite composite,the optimumconditions for polyaspartic acid/montmorillonite composite to remove of Cu²⁺,Zn²⁺and Ni²⁺ ions from aqueous solution were obtained,on this basis,the thermodynamics and kinetics of the adsorption process were also deeply explored.The competitive adsorption experiments of Cu²⁺,Zn²⁺ and Ni²⁺ ions were carried out in the three binary mixed systems: Cu-Zn?Cu-Ni and Zn-Ni,the absorption efficiency of Cu²⁺,Zn²⁺ and Ni²⁺ ions adsorption by polyaspartic acid/montmorillonite composite was Cu²⁺ > Zn²⁺ > Ni²⁺.Finally,the adsorption mechanism and regeneration experiment of polyaspartic acid/montmorillonite composite were preliminarily explored,and it was found that the composite could be recycled four times at least after regenerating with EDTA solution.In conclusion,polyaspartic acid/montmorillonite composite has good removal ability for Cu²⁺,Zn²⁺ and Ni²⁺ ions.