| Seed-watermelon is a kind of watermelon with high yield,which can reach 30 to 60 thousand kilograms per hectare.After removing the seeds,a large number of waste seedwatermelon peel will be generated.Long-term accumulation of seed-watermelon peel will produce a large number of bacteria,and the rotten peel will produce toxic gas,which will pose a threat to human health and the environment.Seed-watermelon peel contains amino acid,polysaccharide and cellulose,which is a good natural material for preparing polymers.Using seed-watermelon peel to prepare superabsorbent polymer can help the recycling of waste resources and the increase of added value,which can reduce the burden on the environment.Superabsorbent polymer as a kind of absorbent material is widely used in agriculture,construction and other industries because of its good water retention ability.At present most commodities on the market are prepared with petroleum-based materials.The poor degradability of these commodities will cause certain harm to the environment.With the increase of people's awareness of environmental protection,environment-friendly materials gradually become the darling of the market.In this thesis,biomass waste and petroleum-based materials are polymerized together to prepare a polymer that has the advantages of low cost,degradability and stable performance.And the excellent performance of the product and its application will be explored.Details are as follows:1.A material with high water absorption rate was prepared by free radical polymerization using biomass waste seed-watermelon peel as raw material,acrylic acid as graft monomer and modified palygorskite clay as filler,respectively.The influence of monomer,initiator,crosslinking agent,degree of neutralization,modified palygorskite clay and particle size on the water absorption rate and water retention capacity of the superabsorbent polymer were investigated to optimize the optimal amount of each influencing factor under the maximum swelling rate.The structure,morphology,thermodynamic properties of the prepared samples with the maximum swelling rate were characterized.The results showed that the polymer had more pore structure,good stability,water absorption and water retention.In distilled water,tap water and 0.9% Na Cl solution,the optimal water absorption was 1286.4 g/g,207 g/g and 103.9 g/g,respectively.The superabsorbent polymer soaked in distilled water has a water retention rate of 90% after12 h at 25 ?.2.A kind of superabsorbent material which can release nitrogen was prepared by free radical polymerization using seed-watermelon peel as raw material,acrylic acid and urea as monomer.The dosage of different influencing factors was optimized to obtain the superabsorbent polymer with the best performance,and the superabsorbent polymer was characterized,and the outflow and rate of nitrogen in the superabsorbent polymer and urea were investigated.The results showed that the polymer with relatively good stability,water absorption,water retention and obvious pore structure.In distilled water,tap water and 0.9% Na Cl solution,the optimal water absorption reached 1151.05 g/g,223.8 g/g and101.45 g/g,respectively.Soil leaching tests showed that the nitrogen release capacity of the prepared material was slower and longer than that of urea.3.Two kinds of superabsorbent polymers prepared and two kinds of conventional superabsorbent polymers purchased were used to conduct seed germination and seedling growth tests of Gymnocarpos przewalskii and Isatidis Radix.The application performance of superabsorbent polymers was evaluated by germination rate,germination potential,root length,shoot length,water consumption,fresh weight,dry weight and survival rate.Results show that during the G.przewalskii seed germination and seedling growth process,compared with the control group,water consumptions of two types of superabsorbent polymer SWMP-g-PAA/mPGS and SWMP-g-P(AA-co-Urea)/mPGS reduced by 40% and 57%,respectively.The germination rate was 2% and 3% higher than the control group,and the germination potential was 2.7% and 3.7% higher than the control group.The root length was 0.5 cm and 2.2 cm higher than the control group.The shoot length was 0.1 cm and 0.5 cm lower than the control group.The bioaccumulation was 2.3 times and 1.59 times higher than the control group,and the survival rate of SWMP-g-P(AA-co-Urea)/mPGS was 11% higher than the control group.In I.Radix seed germination and seedling growth process,the water consumption of the two polymers in the control group was basically the same as that of the laboratory,and the germination rate was 13.4% and 4% higher than that of the control group.The germination potential of SWMP-g-PAA/mPGS was 10% higher than that of the control group.The root length of the control group was 0.8 cm and 1.2 cm higher than that of the self-made group,and the stem length of the control group was 0.3 cm and 0 cm higher than that of the selfmade group.The bioaccumulation of the self-made two polymers were 1.06 times and1.33 times higher than that of the control group,and the survival rate was basically the same as that in the control group.Based on the above data,it can be found that the superabsorbent polymer made in the laboratory can effectively reduce water consumption,promote the germination of seeds and the growth of seedlings,increase the biological accumulation of plants and improve the survival rate of seedlings. |
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