| Dye stuffs provide a more attractive and brighter variety of colors and are therefore widely used in the textile,paper and food industries.And the demand for chemical dyes is rising worldwide because of their lower cost compared to natural dyes.The annual consumption of synthetic dyes in the textile industry is very high and produces huge amounts of pollutants in the waste water.The presence of dyes reduces the clarity and aeration of the water,which prevents plants from photosynthesising properly and leads to a decrease in dissolved oxygen values.Secondly,the discharge of dye effluent into water systems from dye manufacturing plants or dye consuming industries is a major risk to water quality,human health,animals,plants and aquatic life,so treatment of dye effluent is an urgent priority.There are currently three main types of treatment methods for dye wastewater,chemical,biological and physical methods.Of these,physical adsorption is the most cost effective and efficient method.Metal organic framework materials（MOFs）are widely used in adsorption because of their high specific surface area and high porosity.UiO-66-NH2 is a chemically stable,water-resistant MOF,which offers advantages for the adsorption of dyes in water,but the presence of powder form makes it difficult to recover in water.Cellulose,the most abundant natural polymer in nature,is also inherently acid-and alkali-resistant and insoluble in water,which provides a suitable carrier for UiO-66-NH2.In this paper,cellulose acetate nanofibers were prepared based on centrifugal spinning technology,and then regenerated by deacetylation and used as a carrier to compound UiO-66-NH2 using in situ growth to prepare a material for easy recovery and efficient adsorption of the dye Rose Bengal（RB）.The main studies are as follows:（1）Cellulose acetate nanofibers were prepared by centrifugal spinning technique and the process parameters were optimised through experimental verification.It was finally determined that:when the spinning solution concentration was 11wt%,the spinneret diameter was 0.11 mm,the collection distance was 15 cm and the motor speed was 5500 rpm,the spun cellulose acetate nanofibers had the most uniform morphology and the average fiber diameter was in the range of 600-700 nm.On this basis,cellulose acetate nanofibers were deacetylated to prepare cellulose nanofiber membrane.The successful regeneration of the cellulose nanofibers was verified by FTIR,and the morphology and diameter distribution of the nanofibers before and after the treatment were compared by SEM,and it was found that there was no change in the morphology of the regenerated cellulose nanofibers and the overall diameter became smaller.（2）UiO-66-NH2 was immobilised on the cellulose nanofiber membrane by in situ growth method.Analysis of SEM,FTIR and XRD data showed that UiO-66-NH2 was uniformly grown on the surface of the cellulose nanofiber membrane.Analysis of TGA and BET data showed that the complexes possessed the thermal stability characteristics of UiO-66-NH2 and also possessed a certain specific surface area.In a study of the loading capacity of cellulose nanofiber membrane with UiO-66-NH2,it was found that each 0.1g of cellulose nanofiber membrane could be loaded with approximately 10mg of UiO-66-NH2.（3）The successfully prepared cellulose nanofiber membrane/UiO-66-NH2complex was applied to the adsorption of the dye Rose Red.The adsorption behavior of the complex and UiO-66-NH2 was analyzed and compared by studying the adsorption time,solution p H,temperature and the initial concentration of the dye,and it was found that both the complex and UiO-66-NH2 matched the pseudo-second order adsorption kinetic model,which is in accordance with the recycling performance of the complexes showed that after six cycles of adsorption experiments,the adsorption capacity of the complexes for the dye Rose Red remained at 86%of the maximum adsorption capacity.In the presence of competing ions in the real water,the adsorption capacity of the complexes did not suffer,indicating that the complexes are very promising for application. |
PDF Full Text Request