Synthesis And Applications Of Seabuckthorn Branch Powder Based Superabsorbent Composite

The superabsorbent resin is a new type of functional polymer that can absorb its own weight several thousand times the water.It has a good water retention capacity and a strong ability to withstand pressure.With the advantage of excellent performance,superabsorbent has been widely used in various fields.In this paper,a new biodegradable,environmentally friendly and highly water-absorbing composite material was prepared used seabuckthorn branch power as the raw materials,and combined with the traditional superabsorbent resin.It was applied to the field of dye wastewater treatment and urea sustained release,which not only overcomed the shortcomings of traditional superabsorbent polymers including high production cost,weak salt resistance,and poor biodegradability,but also achieved the purpose of waste utilization.The main research contents are listed as follows:?1?Preparation and properties of SBP-g-P?AA-co-AM?superabsorbentA seabuckthorn branch powder based superabsorbent superabsorbent?SBP-g-P?AA-co-AM??were synthesized by free-radical aqueous copolymerization,using seabuckthorn branch power as the raw material,acrylic acid and acrylic amide as monomer,ammonium persulfate??NH4?2S2O8?as initiator and N,N'-Methylenebisacrylamide?MBA?as crosslinker.The structure and morphology of the hydrogels were characterized by FT-IR spectroscope and scanning electron microscope.In the study of the swelling behavior of SBP-g-P?AA-co-AM?composite superabsorbent,the effect of pH,temperature and salt irons are investigated.And the kinetic model was used to analyze swelling process.The results showed that the composite has the best absorbency of 130.0 g/g in distilled water and 25.0 g/g in 0.9 % NaCl solution and has good water retention properties at 60?.The swelling kinetics of SBP-g-P?AA-co-AM?in distilled water and in 0.9 % Na Cl solution could be fitted well with a pseudo-second-order kinetic model.It was found that the higher the temperature,the smaller the equilibrium water absorption of SBP-g-P?AA-co-AM?,and the shorter the time required to achieve the equilibrium.When the pH was 6,SBP-g-P?AA-co-AM?had the maximum water absorption capacity.The effect of the salt ions in the swelling capacity was Na+>K+>NH4+>Mg²⁺>Ca²⁺>Fe³⁺.Moreover,the absorbencies ability in distilled water and 0.9 wt% NaCl aqueous solution via five cycles remained about 90.2 % and 80.8 % of the original maximum value,which indicated that SBP-g-P?AA-co-AM?has a good repeat water absorption capacity.?2?Study on adsorption of methylene blue by SBP-g-P?AA-co-AM?superabsorbentSBP-g-P?AA-co-AM?superabsorbent was used as adsorbents for the removal of methylene blue dye in aqueous solutions.In the study of the adsorption behavior of methylene blue dye?MB?,variables such as time,concentration of solution,pH and temperature are investigated.And the kinetic model,isotherm equation and thermodynamic equation were used to analyze adsorption process.The results showed that the SBP-g-P?AA-co-AM?superabsorbent has a good adsorption effect on methylene blue,the optimal pH value is about 7.When the concentration of methylene blue ranges from 5mg/L to25mg/L,the adsorption capacity is enhanced with the increasing of initial concentration.The temperature has slightly effect on the adsorption processes,with the development of temperature,the equilibrium adsorption amount decrees slightly.The pseudo-second-order kinetic equation is suitable for simulation of the adsorption processes.The Langmuir model was found to be in better correlation with the experimental data,indicating the absorption belongs to monolayer adsorption.The negative adsorption values ?G and ?H show the adsorption process is spontaneous and exothermic.?3?Study on slow-release behavior of urea by SBP-g-P?AA-co-AM?superabsorbentThe SBP-g-P?AA-co-AM?composite was swollen in urea solution until equilibrium swelling and then the slow-release urea?SRU?was obtained.The urea loading percentage increased along with the increase of the urea solution concentration,while the swelling capacity of SBP-g-P?AA-co-AM?composite decreased slightly with the increase of urea solution concentration.The SRU was used as the release material for urea in aqueous solution.The effects of release environment such as pH,Na Cl concentration and temperature were investigated,and the release process was analyzed by diffusion model.The results showed that when the pH value was 2 and 11,the urea release rate was faster,and it took about 40 min to reach the release equilibrium,while the pH value was 7,the urea release rate was slowed down and it took about 60 min to reach the release equilibrium.When the concentration of Na Cl aqueous solution ranges from 0.0 mol/L to 0.05 mol/L,the the urea release rate is enhanced with the increasing of NaCl concentration.When the temperature of medium solution ranges from 30 to 50 ?,the urea release rate is enhanced with the development of temperature.The diffusion model indicates that the release process was characterized by non-Fickian diffusion.The transport mechanism can be characterized by the relaxation of the hydrogel network and diffusion through the pores.