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Lanzhou Jiaotong University (2018)

Characteristics and Preparation of Desert Algae Soil Crust Mixed with Polymer Sand-fixation Material Based on Attapulgite

张文杰;

Titre : Characteristics and Preparation of Desert Algae Soil Crust Mixed with Polymer Sand-fixation Material Based on Attapulgite

Auteur : 张文杰;

Grade : Master’s Theses 2018

Université : Lanzhou Jiaotong University

Résumé
Land desertification,which is widely distributed in the world,has always been the serious ecological problems.China is one of the countries that are seriously harmed by desertification.The economic losses caused by desertification are as high as 100 billion yuan each year,which makes the task of desertification prevention become more and more urgent.It is of great significance to prepare an advanced,eco-friendly and low-cost sand-fixation techniques and materials.There are various limitations in the general sand-fixation material and technology for application.A new biological sand-fixation material were successfully prepared by combining the plant(artificially cultivated desert algae)and chemical material(superabsorbent polymer based on attapulgite)in this study.The common higher plants are difficult to survive in desert because of the serious water-shortage,strong evaporation and severe wind erosion,while the desert algae is not.The superabsorbent polymer material has the advantages of quick solidification and strong water storage capacity,which could provide a stable environment and moisture support for the growth of plants.In addition,the influence of medium pH and plant growth regulator on artificial cultivation of desert algae was studied,in order to create the optimum condition to accelerate the growth and reproduction of algae.The superabsorbent polymer material was modified with attapulgite clay to improve its water absorption capacity and mechanical properties and reduced the cost.The content of this study is as follows:The physiological characteristics of desert algae were investigated under artificial culture conditions.The results showed that the value of the malondialdehyde was lower when the pH of medium was 7.5,on the contrary,the chlorophyll a,soluble protein and soluble sugar was maximum.It suggested that the alkaline environment was more suitable for the growth and metabolism of desert algae.The value of malondialdehyde was decreased with the increase of 6-BA concentration.When the concentration of growth regulator 6-BA was 0.5 mg/L,the value of chlorophyll a and soluble sugar was maximum.It suggested that the growth regulator had a regulatory effect on the growth of desert algae.The influence of the ultrasonic power and the content of attapulgite on swelling behaviors and the water retention of an organic-inorganic composite superabsorbent material(superabsorbent polymer based on attapulgite)was investigated.The polymer was prepared in aqueous solution by graft copolymerization of partially neutralized acrylic acid(AA),acrylamide(AM),and acid-activated attapulgite clay using potassium persulfate as an initiator and N,N-methylenebisacrylamide(MBA)as a cross linker.The results show that the graft copolymerization took place between acid-activated attapulgite clay and organic monomers.An appropriate amount of acid-activated attapulgite clay can effectively improve the absorption capacity.The polymer give the best absorption up to 1257.54 g/g in distilled water and 209.45 g/g in 0.9 wt% NaCl solution,when the ultrasonic power was 200 W and the content of acidactivated attapulgite clay was 10%(mass fraction).The artificially cultivated desert algae and superabsorbent polymer based on attapulgite were mixed and inoculated on the sand in the petri dishes to grow into the artificially cultivated desert algae soil crust,which was used as a sand-fixation material,under laboratory conditions.The physiological characteristics of the crust was investigated to study the optimum combination and proportion of the algae with the polymer,and the influence of moisture to the artificially cultivated desert algae soil crust.The results showed that the optimal compounding ratio of the artificially cultivated desert algae and superabsorbent polymer based on attapulgite was 1:2,and the optimal compounding method is A1.That was the polymer was mixed with some sand in the ratio of 1:10 and sprinkled on the sand surface,and then the algae was evenly inoculated on it in the ratio of 1:10 with polymer.The value of chlorophyll a,thickness,and fresh weight of artificially cultivated desert algae soil crust formed under such condition was the maximum.Moisture has an important influence on the formation of the crust and arid environment was harmful to the formation and growth of crust.The value of chlorophyll a,thickness,and fresh weight of artificially cultivated desert algae soil crust were the maximum,when the moisture was 15 mL/time.The sand fixation effect of artificially cultivated desert algae soil crust were studied by measuring the compressive strength,permeability,water resistance,erosion resistance,water retention and frost resistance of the crust.The results showed that the crust was better in compressive strength,water resistance,erosion resistance,water retention and frost resistance,and can play a good role in sand fixation.In this study,the artificially cultivated desert algae and superabsorbent polymer based on attapulgite were used for sand-fixing.The technology can lay the foundation for desertification management,regional vegetation restoration and ecological succession.

Mots clés : Desert Algae; Biological Soil Crust; Superabsorbent Polymer; Attapulgite; Sand Fixation;

Présentation (CNKI)

Page publiée le 19 mai 2019