5,366 research outputs found

    A-STATE-OF-ART REVIEW ON ADDITIVES FUNCTION ON POLYMERIC MEMBRANE PERFORMANCE FOR WASTEWATER TREATMENT

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    In this article, the recent development of polymeric membrane fabrication using additive for wastewater treatment is presented. The application of this substance has been recognized reliable to increase membrane performance against fouling phenomenon, especially for purifying industrial wastewaters that mostly have high loading of hazardous pollutants. The effects of modification techniques through additives addition on membrane casting solution are considerably included. This paper also discusses membrane fouling mechanism and other existing technologies available for treating contaminated water. Despite the existence of review paper discussing membrane fouling mitigation on literature, there is still the need of comprehensive review related to the novel technology regarding additive blending on membrane, especially on polymer-based membrane for water pollution control. Eventually, clear conclusion can be drawn that the suitability of additive substances and its composition as well as suitable operating conditions have great leverage on polymeric membrane performance regarding its anti-fouling and hydrophilic level

    Polyvinyl alcohol size recovery and reuse via vacuum flash evaporation

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    Polyvinyl alcohol (PVA) desize effluent is a high COD contributor to towel manufacturing plant's Primary Oxygenation Treatment of Water operation, and being non-biodegradable, is a threat to the environment. When all-PVA/wax size is used in weaving, significant incentives exist to recover the synthetic polymer material from the desize wash water stream and reuse it. A new technology that would eliminate the disadvantages of the current Reverse Osmosis Ultrafiltration (UF) PVA recovery process is Vacuum Flash Evaporation (VFE). This research adapts the VFE process to the recovery and reuse of all-PVA size emanating from towel manufacturing, and compares the economics of its implementation in a model plant to current plant systems that use PVA/starch blend sizes with no materials/water recovery. After bench scale research optimized the VFE PVA recovery process from the desize effluent and determined the mass of virgin PVA that was required to be added to the final, recycled PVA size formulations. The physical changes in the recycled size film and yarn composite properties from those of the initial (conventional) slashing were determined using a number of characterization techniques, including DSC, TGA, SEM, tensile testing, viscometry, number of abrasion cycles to first yarn breaks, microscopy and contact angle measurements. Cotton chemical impurities extracted from the yarns during desizing played an important role in the recovered PVA film physical properties. The recovered PVA improved the slashed yarn weave ability. Along with recovered PVA, pure hot water was recovered from the VFE. Virgin wax adds to the final, recycled size formulations were determined to be unnecessary, as the impurities extracted into the desize effluent stream performed the same functions in the size as the wax. Using the bench results, the overall VFE process was optimized and demonstrated to be technically viable through six cycles, proof-of-concept trials conducted on a Webtex Continuous Pilot Slasher. Based on the pilot scale trials, comparative economics were developed. Incorporation of the VFE technology for PVA size recovery and recycling resulted in ~3.2M/yearinsavingsovertheconventionalPVA/starch/waxprocess,yieldingarawROIoflessthanoneyearbasedona3.2M/year in savings over the conventional PVA/starch/wax process, yielding a raw ROI of less than one year based on a 3M turnkey capital investment.Ph.D.Committee Chair: Dr. Cook, Fred L.; Committee Member: Dr. Carr, Wallace W.; Committee Member: Dr. Parachuru, Radhakrishnaiah; Committee Member: Dr. Realff, Matthew J.; Committee Member: Dr. Muzzy, John D

    Poly (ɛ-caprolactone) nanofibrous ring surrounding a polyvinyl alcohol hydrogel for the development of a biocompatible two-part artificial cornea

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    The study aimed to fabricate and characterize a 2-part artificial cornea as a substitute for penetrating keratoplasty in patients with corneal blindness. The peripheral part of the artificial cornea consisted of plasma-treated electrospun poly (ɛ-caprolactone) (PCL) nanofibers, which were attached to a hydrogel disc of polyvinyl alcohol (PVA) as a central optical part. The physical properties of the prepared artificial cornea, including morphology, mechanical properties, light transmittance, and contact angle, were assessed. Cell attachment and proliferation studies were performed on rabbit limbal stem cells. The SEM image of the polymeric system showed that the peripheral part formed a highly porous scaffold that could facilitate tissue biointegration. Assessment of the mechanical properties of the peripheral nanofibrous part and the hydrogel optical part showed suitable elasticity. Young’s modulus values of the electrospun PCL skirt and PVA hydrogel core were 7.5 and 5.3 MPa, respectively, which is in line with the elasticity range of natural human cornea (0.3–7 MPa). The light transmittance of the central part was >85% when measured in the 400–800 nm wavelength range. The plasma-treated PCL nanofibrous scaffold promoted limbal stem cell adhesion and proliferation within 10 days. These results confirmed that the polymeric artificial cornea showed suitable physical properties and good biocompatibility and epithelialization ability

    A review of natural fiber reinforced poly(Vinyl alcohol) based composites: application and opportunity

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    Natural fibers are fine examples of renewable resources that play an important role in the composites industry, which produces superior strength comparable to synthetic fibers. Poly(vinyl alcohol) (PVA) composites in particular have attracted enormous interest in view of their satisfactory performance, properties and biodegradability. Their performance in many applications such as consumer, biomedical, and agriculture is well defined and promising. This paper reviews the utilization of natural fibers from macro to nanoscale as reinforcement in PVA composites. An overview on the properties, processing methods, biodegradability, and applications of these composites is presented. The advantages arising from chemical and physical modifications of fibers or composites are discussed in terms of improved properties and performance. In addition, proper arrangement of nanocellulose in composites helps to prevent agglomeration and results in a better dispersion. The limitations and challenges of the composites and future works of these bio-composites are also discussed. This review concludes that PVA composites have potential for use in numerous applications. However, issues on technological feasibility, environmental effectiveness, and economic affordability should be considered

    Design and Fabrication of Biomorphic Scaffolds for Tissue Regrowth by 3D Printing

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    Tissue engineering has shown a need for three-dimensional (3D) tissue scaffolds for cell growth as an improvement over slab scaffolds. We present a novel scaffold design and manufacturing process, utilizing biomorphic scaffold shapes based on computational models and defined by optimal surface area to volume ratios. Using these models and a low-cost 3D printer, we developed fractal-based biocompatible 3D tissue scaffolds that supported cell proliferation

    Evaluation of the Performance and Cost-Effectiveness of Engineered Cementitious Composites (ECC) Produced from Region 6 Local Materials

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    The project objective is to develop cost-effective Engineered Cementitious Composites (ECC) with locally available ingredients in Region 6 to address the deficiencies observed in ordinary concrete materials. The study explored the utilization of two types of river sands (coarse and fine), two types of PVA fibers (long and short), four levels of cement replacement with Class F fly ash, and the implementation of recycled crumb rubber in the performance of ECC materials. A total of 24 mix designs were prepared and evaluated in compression, tension, and bending to assess its mechanical properties. Furthermore, the cracking characteristics of the materials produced were evaluated to assess the durability potential of these composites. Lastly, the cost of each mix design and the feasibility of ECC implementation in transportation infrastructure were assessed. The experimental results showed that implementing crumb rubber and/or increasing contents of fly ash in the mixtures produced a positive impact in the ductility of the materials. However, a tradeoff between ductility and strength was observed. Furthermore, the utilization of the different types of sand evaluated in this study produced minor effects in the mechanical properties of ECCs evaluated. The properties of the materials developed in this study were exceedingly superior than that of regular concrete. It was concluded that ECC materials are promising for the future of transportation infrastructure

    Integrated Sequential Anoxic-Aerobic (ISA) Reactor for Wastewater Treatment

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    Wastewater treatment is the process of removing contaminants from raw water. The goal is to produce water that follows the standards, to meet the government standards which can be used for the specific purpose of human consumption. Rubber wastewater treatment includes removing of the particles, organic molecules, bacteria, algae, virus and toxic metals. The rubber industry is one of the industries that produce high amounts of the liquid and solid waste. In this research the aerobic-anoxic treatment method will be used to treat rubber wastewater. The two methods combined in one reactor which is Aerobic-Anoxic Sequential Reactor (ISA). It consists of a cylindrical tube with 160 cm height and 6.5cm diameter. The upper part used as anoxic tank where nitrification take place. During nitrification process ammonia (NH4-N) is oxidized to nitrate (NO2-N) and then to nitrate (NO3-N). Nitrate produced in the upper part of the reactor. The effluent from this process is recycled back for oxidation reduction reactions in denitrification process, which convert nitrate to nitric oxide, nitrous oxide, and nitrogen gas

    POLYVINYL ALCOHOL (PVA) FIBER-REINFORCED RUBBER CONCRETE AND RUBBERIZED SELF-COMPACTING CONCRETE

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    This study experimentally investigates the mechanical performance and durability of Polyvinyl Alcohol (PVA) fiber-reinforced rubber concrete and the rubberized self-compacting concrete. The waste rubber particles were introduced as a partial replacement of fine aggregate in the plain concrete. In addition, the waste tire rubbers were pre-treated with alkali surface treatment method to enhance the performance. The PVA fibers were added to the concrete mixes to enhance the post-failure resistance and thus fracture energy. Rubberized fiber concrete samples were prepared with different fine aggregate replacement ratios and the optimum fiber content. At the same time, the rubber particles had been used to partially replace the fine aggregate in normal self-compacting concrete (SCC). The rubberized self-compacting concrete (RSCC) had also been prepared with different rubber contents. The effects of NaOH treatment method had been evaluated in the self-compacting concrete. For these samples, the mechanical performance including compressive strength, indirect tensile strength, and flexural behavior was measured to compare with control samples. The transport property was also detected by electrical resistivity test. The durability performance such as alkali-silica reaction (ASR) expansion and drying shrinkage were evaluated and compared with control samples. The test results of the PVA-fiber reinforced rubber concrete showed that it could achieve a high fracture energy and maintain xvi a high mechanical performance after addition of recycled rubber and PVA-fiber, furthermore, the modified specimens showed a better performance in durability than control samples. At the same time, the results from rubberized self-compacting concrete (RSCC) also indicated that after using of NaOH surface treated rubbers can successfully achieve high-strength requirement and improve durability performance. Overall, the polyvinyl alcohol (PVA) fiber could be considered to improve the mechanical performance and durability in normal rubberized concrete. In addition, the NaOH surface treatment method for rubber particles could improve the performance of rubberized self-compacting concrete (RSCC), thus achieve a high-strength and good durability with the recycled tire aggregate
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