| There is a large number of oily wastewater in the oil extraction,processing and transportation,machinery manufacturing,textile dyeing or finishing and other industrial production every year.Daily life will also produce oily wastewater,such as kitchen fumes,human fats and oils.Among them the degree of oil pollution in industrialization is particularly serious,and some have caused irreversible damage to the environment.Some natural fiber materials have attracted more and more attention by the field of oil absorption duo to their strong ability to absorb oil,rich in resources,renewable,biodegradable and other advantages.Cattail fiber belongs to this type of resources,but most of the current fibers fend for themselves,not fully utilized,resulting in a great waste of resources.In this paper,the physical and chemical properties of the single cattail fiber structure,the fiber structure and performance were discussed.The adsorption properties of several natural fiber assemblys were studied.Through the air flow method and the thermal adhesive method of the three-dimensional filter fiber fabric production,the high efficiency oil and water separation device of cattail fiber was designed and constructed.By combining the three-dimensional structure design of the cattail fiber,the oil and water separation,the fiber centrifugal cycle and the oil recycle function are realized simultaneously,which provides the basis and reference for the application of cattail fiber in oil and water separation.The main contents and conclusions of this paper include: 1.Structure and performances of cattail fiberThe surface and cross-sectional structure of the cattail fiber were measured by scanning electron microscopy and three-dimensional video microscopy.The main groups were determined by infrared spectroscopy.The surface wax content was measured by Soxhlet extraction method.The surface adhesion energy of the fiber was calculated by using the OCA15 EC optical contact angle tester.Based on the geometrical mean contact angle method,the surface free energy of the fiber and the polarity and non-polar component of the fiber were calculated.And finally the wetting properties of the fiber were analyzed.Results show that: The structure of cattail fiber is similar to the duo-like fiber of feather,the longitudinal section structure is similar to the bamboo which contains a number of open-type cavity.The unique structure of the cattail fiber structure can help to maintain a large number of static air and increase the specific surface area of cattail fiber,which is conducive to oil adsorption and storage.The number of a single fiber is in the range of 30 to 80,the average length is 7.9mm,the average fineness is 14.3?m.Cattail fiber and kapok fiber has a similar component,which are cellulose fibers,containing wax more than 10%.The contact angle of the cattail fiber with water is about 130 °,and the contact angle with the vegetable oil is about 60 °,indicating that the fiber is oleophylic and hydrophobic fiber.The dynamic spreading process of the oil on the fiber layer is divided into three stages,namely,the rapid spreading stage of 0ms to1000 ms,the slow spreading stage from 1000 ms to 2000 ms,and the stabilization stage after 2000 ms.The surface free energy of the cattail fiber is 45.64 m N/m,where the polar component is 2.69 m N/m,the dispersion component is 42.94 m N/m,the dispersion and polarity ratio is 15.96.Therefore the cattail fiber has better oleophylic and hydrophobic performance.2.Oil adsorption performance of cattail fiberThe oil absorption performance of the loose cattail fibers was evaluated by oil absorption,oil retention and oil suction buoyancy performance,which is compared with the oil absorption performance of the kapok fiber.Results show that the oil absorbency of the cattail fiber was 11.91g/g,which was nearly 12 times of its own mass.It is lower than that of kapok and cotton fiber,25.79 g/g of cotton wool and 14.98 g/g of cotton fiber.Cattail fiber and kapok fiber oil retention rate can reach more than 90%,cotton fiber assembly oil rate of more than 80%,indicating that the three fibers have a good oil retention performance.The oil buoyancy performance under the same conditions of cattail fiber,kapok fiber and cotton fiber assembly: the three fibers in half the volume of immersion time are about 30 s,and in all the immersion time difference is relatively large,and the cotton fiber assemblys were For 90 s and 94 s,are closer,while the kapok fiber assembly needs 147 s.Completely immersed in the oil in the cattail and kapok fiber assemblys suspended,cotton fiber assemblys sink.3.Oil and water filtration device and filter preparationThe instrument was designed by using Soildworks software.A set of oil and water separation,fiber centrifugal cycle and oil recycle function in one of the oil and water separation device was built.The tapered inner cylinder is the separation of the core components of the instrument,making the oil under the action of centrifugal force flows the tapered inner wall counter currently to the top of the well with a symmetrical notch so as to enter the oil reservoir between the inner and outer cylinders to achieve oil collection.The cattail fiber flakes was prepared by airflow method,the three-dimensional molding of the flakes was prepared by three-dimensional mold.The three-dimensional filter with a high porosity and a high porosity was obtained by the baking method.The oil and water mixture is filtered in conjunction with the apparatus involved.The use of diesel,edible oil repeated tests to determine the three-dimensional filter volume density,flow rate,instrument speed and centrifugal time and other test parameters.4.Evaluation of oil-water separation effect of cattail fiber assemblyThe separation efficiency of three-dimensional filter oil was evaluated by centrifugal rate,oil recovery rate,oil absorption ratio,water absorption rate,residual oil rate and filtration efficiency.The oil flow rate of 7.5m L/min and water flow rate 750 m L/min were mixed by the three-way tube,going through the nozzle into the cone-shaped inner tube,the three-dimensional filter body with 0.01 g / cm~3,0.02 g / cm~3 and 0.03 g / cm~3 and other three different bulk density.Results show that: Under the same bulk density condition of the three-dimensional filter body,the breakthrough time of vegetable oil is longer than that of diesel oil,and with the increase of bulk density,the breakthrough time difference between the two kinds of oil increases.The breakthrough rate of vegetable oil was 40 min,which is 10 min longer than that of diesel oil at 0.01 g/cm~3.The oil absorbency of vegetable oil is higher than that of diesel oil,the vegetable oil reaches 22.21 g/g and the diesel oil is 18.12 g/g at 0.01 g/cm~3.With the increase of fiber density,the oil absorbency of the two kinds of oil showed a decreasing trend,and the water absorption rate changed little,which was about 3 times of its weight.In terms of oil recovery,when the bulk density were 0.01g/cm~3,0.02g/cm~3 and 0.03g/cm~3,the recovery rate of vegetable oil were 92.56%,90.18% and 89.42%,respectively,the recovery rate of diesel oil were 90.51%,86.90% and 83.71%,respectively.The recovery rate of the two kinds of oil are all more than 83%,the remaining oil is not more than 10% of vegetable oil,is about 16% of diesel oil.Cattail fiber filter can be recycled at least 3 times for vegetable oil,at least 4 times for diesel.The three-dimensional cattail fiber filter and the kapok three-dimensional filter are all excellent natural oil adsorption materials.The amount of oil collected for the first time of cattail fiber was higher than that of kapok fiber,but with the increase of the number of cycles,the collection of the fiber was lower than that of kapok fiber.5.The factors influencing the filtration effect of cattail fiber assemblyMany factors such as the types of oil,the structure and density of the assemblys,the concentration and the flow rate of the mixture have influenced on the filtration effect of cattail fiber assembly By using the different oil concentration,different materials and the mixed flow rate of oil and water,the design parameters are optimized to achieve the maximize oil absorption volume and separation efficiency,achieving multiple use of different fiber filters. |
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