Preparation And Properties Of Anti-leakage And Salt Isolation Composite Materials

Northwest China lies deep inland,with strong evaporation and little rainfall,and perennial water shortage,which is a typical arid and semi-arid area.Effective use of precipitation resources is an effective way to alleviate water shortage,but due to deep leakage,most of the rainfall will be wasted,so preventing deep leakage of precipitation is an urgent problem to be solved for water shortage areas.At the same time,water and soil resources are the basis of human survival,water shortage will also inevitably cause land salinization,resulting in degradation of land resources,leading to more serious land desertification phenomena and restricting the economic development of Northwest China.The current research on water resources leakage and saline land improvement only tends to unilateral treatment,and there are problems such as expensive and environmentally unfriendly.Therefore,an environment-friendly polymer material that can prevent deep water leakage and act as saline-alkali isolation layer is prepared to combine water resource management and arable land improvement,which can not only relieve the pressure of water shortage,but also assist saline land management,achieving double benefits.Based on the above research objectives,this paper synthesizes three anti-leakage and salt isolation bifunctional composites by free radical graft copolymerization using the natural clay mineral laterite,which is widely distributed,abundant and inexpensive in nature,as the main raw material,with the addition of environmentally friendly polymers such as guar gum,cassia gum and tragacanth gum.The structure,morphology and thermal stability of the composites were characterized,and the anti-leakage and salt isolation properties were investigated as follows:1.Guar gum-graft-poly（vinyl acetate-co-hydroxyethyl methacrylate）emulsion（GG-g-P（VAc-co-HEMA））were prepared from guar gum（GG）,vinyl acetate（VAc）and hydroxyethyl methacrylate（HEMA）by free radical polymerization and the reaction conditions were optimized.The structure,morphology and thermal stability of the material were characterized by FTIR,SEM,TGA and CA.The clay-based anti-leakage and salt isolation materials were prepared by adding the emulsion to laterite as the main raw material,and the effects of the emulsion content on water retention,anti-leakage and salt isolation properties of the soil were investigated.The results showed that the material has good water retention and water holding properties,and the soil seepage rate and the salt content of soil surface layer were significantly reduced after the addition of the composite material.2.Using cassia gum（CG）,partially neutralized acrylic acid（AA）,dimethyl diallyl ammonium chloride（DMDAAC）and montmorillonite（MMT）as raw materials,the highly absorbent material of cassia gum-graft-poly（acrylic acid-copolymerization-dimethyl diallyl ammonium chloride）/montmorillonite（CG-g-P（AA-co-DMDAAC）/MMT）were prepared by free radical polymerization,and the synthesis parameters were optimized.The structure,morphology and thermal stability of the materials were characterized by FTIR,SEM and TGA.The clay-based anti-leakage and salt isolation bifunctional composites were prepared from laterite with the addition of this highly absorbent material.The clay-based leakage-proof-salt barrier bifunctional composites were prepared from laterite with the addition of this highly absorbent material.The swelling ratio of the material in distilled water,tap water and salt water were 1413 g/g,231 g/g and 115 g/g.The water-holding and water-retention properties,anti-leakage properties and salt isolation properties were also investigated.The results showed that the material can not only effectively prevent the deep leakage of soil water,hold water and retain water,but also effectively inhibit the upward movement of salt to achieve the purpose of saline land improvement.3.The AA-Al₂O₃ powder was prepared by modifying alumina nanoparticles with acrylic acid and optimizing the synthesis reaction conditions.Using tragacanth gum（TG）,partially neutralized acrylic acid（AA）and AA-Al₂O₃ powder as raw materials,the bifunctional composite（TG-g-PAA/AA-Al₂O₃）was prepared by free radical graft copolymerization,and the reaction parameters of the composite were optimized.The structure,surface morphology and thermal stability of AA-Al₂O₃ and TG-g-PAA/AA-Al₂O₃ were characterized by XRD,FTIR,SEM,and TGA,and the synthesis parameters of AA-Al₂O₃ and TG-g-PAA/AA-Al₂O₃ were optimized.The water retention,water-holding and repetitive swelling properties of the materials were investigated,and the effects of different concentrations and types of salt solutions on the absorption multiplicity of the materials were investigated.The anti-leakage and salt isolation properties of the materials were investigated,and with the addition of 0.8%of the materials compared with the control group,the anti-leakage and salt isolation properties were improved by 18.4%and 24.7%,respectively.Therefore,the material is valuable for water resource control and arable land resource improvement in arid and semi-arid areas.