The Preparation Of Two Super-absorbent Polymers And Their Application In The Improvement Of Saline-alkali Soil

At present,with the increasingly enhanced economic activity of human,the contradiction between man and land is increasingly intensified.It can effectively relieve people's pressure on the demand for arable land to developing and utilizing saline-alkali land vigorously.So how to improve the saline-alkali land is particularly important at this stage.As the carrier to migrate the salt of soil,water plays a crucial role in the process of soil salinity accumulating in the surface.Therefore,reducing the evaporation of water in saline-alkali soil and improving water and fertility in the soil will inevitably be the effective ways to improve saline-alkali soil.The super-absorbent polymer is a kind of high polymer with high water-absorbing and water-holding capacity.It has been developed rapidly in recent years.The technology of super-absorbent polymer has been developed into a high-tech chemical water-saving technology.In this study,two super-absorbent polymers were synthesized successfully by a method of aqueous solution polymerization,that using ammonium persulfate?APS?as an initiator,N,N'-methylene bisacrylamide?NMBA?as a cross-linking agent and partially neutralized acrylic acid?AA?as the main polymerization monomer.The super-absorbent polymers of high anti-salt?SRS?was synthesized by introducing the2-acrylamido-2-methylpropanesulfonicacid?AMPS?andisopentenyl polyoxyethylene ether?TPEG-2600A?.The environmentally friendly super-absorbent polymers?C-G-SAP?was synthesized by introducing the chitosan and guar gum.And the experiment of single,factor was used to optimize the various factors in the synthesis process.Under different environmental conditions?solution temperature,pH,salt solution type and concentration?,the environmental adaptability of the two super-absorbent polymers were measured.And added the super-absorbent polymers to saline-alkali soil for leaching test and water and fertilizer evaporation's tests to determine their effects to retain water and fertilizer.The main conclusions of the study are as follows.?1?The optimal conditions of reaction about SRS are neutralized degree of AA is80%,dosage of TPEG-2600A is 1.5 g,dosage of APS is 0.20%of total monomer amount,and dosage of NMBA is 0.02%of total monomer amount.The absorbent efficiency of SRS in deionized water and 0.9%NaCl solution reached 2688 g g^-1and233 g g^-1,respectively.The optimal conditions of reaction about C-G-SAP are neutralized degree of AA is 85%,dosage of GG is 0.2 g,dosage of APS is 0.30%of total monomer amount,and dosage of NMBA is 0.02%of total monomer amount.The absorbent efficiency of C-G-SAP in deionized water and 0.9%NaCl solution reached1128g g^-1and 185g g^-1,respectively.?2?The changes of ambient temperature?4⁸0°C?and pH of solution?4¹0?have little effect on the water absorbent performance of SRS and C-G-SAP.The water-absorbing properties of two kinds of super-absorbent polymers in different cation saline solutions vary greatly.With the increase of the concentration of the saline solution,the absorbent efficiency of the two kinds of super-absorbent polymers were reduced significantly,and the order of influence of the cation type were Mg²⁺>Ca²⁺>Na⁺>K⁺.At the same time,in the environment of high temperature and low temperature,both super-absorbent polymers have good water retention effect.?3?The experiment of leaching showed that the addition of SRS and C-G-SAP can not only effectively reduce the leaching loss of potassium fertilizer and nitrogen fertilizer in saline-alkali soil,but also improve the retentive effect of soil water.And with the increase of the amount of super-absorbent polymer,the retentive effect of water and fertilizer in the soil is more obviously.?4?The experiment of moisture and fertilizer in the soil showed that the addition of two kinds of super-absorbent polymers are beneficial to reduce the loss of moisture and nitrogen fertilizer in the saline-alkali soil.For the content of moisture in the soil,with the increase of the amount of super-absorbent polymer,the loss of water decreases.But the addition of nitrogen fertilizer will increase the evaporation of moisture in the soil,that the content of moisture decrease with the amount of nitrogen fertilizer increases.For the content of nitrogen fertilizer in the soil,the addition of super-absorbent polymer can inhibit the loss of NO₃^--N and NH₄⁺-N in soil.When the added amount of SRS is 0.10%of total weight of the soil,the effect is the best,and when the added amount of C-G-SAP is 0.05%of the total weight of the soil,the effect is the best.