| These years,the acreage of drought and semi-drought districts increased day by day because the global atmosphere became warm.,and the water and soil lost seriously so that the environment deteriorated gradually.The development of agriculture and the survival of humankind were largely influenced in the world.How to effectively use water in the soil and abirritate the bad influence on plant growth has became limelight here and abroad.Nowadays,the situation of our country is that most of north area lacks water,the water and soil of loess altiplano lose seriously and drought happens usually in the south.The main way to fight drought was to irrigate,but this method could not be cartied into practice widely because the investment was large and most areas of our country was mountain,altiplano and foothill.The Super Absorbent Polymer provided a new approach for fighting drought and holding water and soil.Super Absorbent Polymer(SAP)has macromolecule electrolytical molecule expanded capability and contains abundant strong hydrophilic group such as carboxy1 and hydroxide.Also, its tiny crosslinked three dimension network structure baffles molecular more expanded.The molecule can not dissolve but swell because of contravention between the two actions so that this material has peculiar ability in absorbing and retaining water.It will be widely used in the field of farming,horticulture,medicine,sanitation,architecture,daily chemistry and petroleum chemic engineering.Currently,however,some SAP made by simple chemic reagent could not be applied greatly in farming and environment field for high cost and bad environment tompatibility because of the restriction of economy,science and technology.Firstly using acrylic acid,acrylamide,fly ash and illite to prepare fly ash-illite/P(acrylic acid -acrylamide)super absorbent polymet composite material by solution polymerization based on the following calculations:acrylic acid which had innocuity and no sapor was the maximal dosage in preparing SAP.The SAP was made from pure acrylic acid having good absorbent rate but high cost,bad biological compatibility and salt resistance characteristic.Adding acrylamide could ireprove salt resistance characteristic.The fly ash pricked up environmental pollution but could absorb a little water.Fly ash inherited various nutrient element from ancient plant and might improve quality of soil clearly for the transform course of"plant-coal-fly ash"Illite not only had great reservation in our country but had absorbent ability as clay-mineral.Illite had many kinds of deformities so that it possessed smart chemical activity.At the same time,fly ash and illite in preparing SAP contained potassium so that this SAP might improve the situation of lacking pocassium in soil.This study chose orthogonal experiment method to arrange experiments,used natural filtration method to measure the absorbent rate of composite material,and used Fourier transform infrared spectrometer．Ⅹ-ray diffractometer and scanning electron microscope to characterize the sample.Atomic absorption spectrophotometer had been used to measure releasing potassium ion fom fly ash and illite.Composite material became gel after aborbing water.Then the heat stability of gel was mastered by TG-DSC analysis.Water retention, enduring cold performance and second absorbent performance of this material were also investigated.The best technical condition was acquired by orthogonal experiment and calculation when the composite material absorbed distilled water,tap water and 0.9％NaC1 solution absorbency 1695,445.106.3 g.g~-1 at 70℃with the content of fly ash and illite,cross linker.acrylamide and initiator 40％,O.04％,50％,O.10％of the quality of monomer respectively,and neutralization 90％. The absorbency had exceeded the requirement of The National 863 Program and Ministry of Agriculture.The extent of neutralization related mol percent of acrylic acid monomer,and the content of fly ash and illite,acrylamide,cross linker and initiator related quality percent of acrylic acid monomer.The raw material cost of composite material was 5983 yuan per ton according to the data in May,2007.Presently import price of SAP was 15000～18000 yuan per ton and selling price was 18000～22000 yuan per ton in China.Compared to SAP,the raw material cost of cornposite material was law because composite material contained fly ash and illite.The composite material had excellent water retention for the gelatin could keep 50％water quantity after dried 8 days under 25℃or 24 hours under 70℃.And it had good absorbent performance at 0℃so that it had good enduring cold performance.Its performance was steady among 0～120℃.And this material could be used more man one time for good second absorbent performance.In distilled water.potassium ion in fly ash was released 0.00％,potassium ion in illite was released O.55％,and potassium ion in fly ash and illite in fly ash-illite/P(acrylic acid- acrylamide)super absorbent polymet composite material was released 12.80％namely the release extent was elevated greatly.So the composite material had many purposes.The mechanism of illite release potassium was that displacement reaction arose between K+ in illite and Na+ in acrylic acid sodium after illite compounded into composite material. The mechanism of fly ash release potassium was that the chemical reaction between fly ash and acrylic acid arose so that K2O in fly ash vitreous body was dissolved to release potassium ion.Infrared spectrum indicated that theory presumption was coincident to experiment that the body of SAP was sodium polyacrylate and polyacrylamide and -OH from illite had combined with acrylic acid in the course of polymerized reaction. XRD analysis indicated that crystal mineral in fly ash did not react with macromolecule. Scanning electron microscope analysis indicated fly ash and illite grain distributed in polymer like detached island. Most mineral was packaged by polymer. Clear interphase was not found between mineral and polymer proving that mineral and macromolecule compounded well.To sum up,composite material not only possessed good water absorbency like traditional SAP, but also cost lowly, had good biology compatibility, had good enduring cold performance and could release potassium. As a kind of excellent and cheap soil improvement material, this composite material will be applied widely in farmland fighting drought and protecting water, crop protecting young plant and increasing production, desert and wasteland fathering. Super absorbent polymer composite material has been universally thought as the fourth farm chemical produce which will be very accepted by peasant following the chemical fertilizer, pesticide and mulching film.
|
PDF Full Text Request