Economical treatment of reverse osmosis reject of textile industry effluent by electrodialysis–evaporation integrated process

Membrane separation methods such as electrodialysis (ED) can reduce the volume load on evaporators by facilitating further concentration of rejects from reverse osmosis (RO) plants. ED studies were carried out on a bench-scale system using five membrane cell pairs to obtain a textile effluent concentrate containing approximately 6 times the quantity of salts present in the RO reject. The limiting current densities were determined to be in the range 2.15–3.35 amp/m² for feed flow rates varying from 18 to 108 L/h. Apart from feed rate, the influence of volume of concentrate and current on membrane performance was evaluated to optimize current utilization. An estimation of energy requirement of an integrated process constituting ED and evaporation for concentration of inorganics present in textile effluent from 4.35% to 24% was made and found to be approximately one eighth of the operating cost incurred by evaporation alone. Detailed design of a commercial ED system revealed that a membrane area of 13.1 m² was required to treat a feed rate of 1500 L/h. The payback period to recover capital investment was found to be 110 days.     

The desalting and recycling of wastewaters from textile dyeing operations using reverse osmosis

The wastewater from the textile dyeing operations was separated into a concentrate stream, rich in salts and dyes, and a purified product water stream using reverse osmosis membranes. Three membrane materials and three module configurations were used, namely : polyamide (hollow fine fiber configuration ), cellulose acetate ( spiral wound and tubular configurations ) and hydrous Zr(IV)- polyacrylate ( tubular configuration ). The modules were tested for periods ranging from 600 hours to more than 1000 hours under actual field conditions. Membrane flux and rejection were monitored throughout the operation and samples of the feed and product water were analysed chemically. The successful operation of the R.O. equipment under field conditions demonstrated the applicability of this process in the desalination of dyeing wastewater.     

Atmospheric air-plasma treatments of polyester textile structures

The effects of atmospheric air-plasma treatments on woven and non-woven polyester (PET) textile structures were studied by surface analysis methods: wettability and capillarity methods, as well as atomic force microscopy/lateral force microscopy (AFM/LFM). The water contact angle on plasma-treated PET decreased from 80° to 50–40°, indicating an increase in the surface energy of PET fibres due to a change in the fiber surface chemical nature, which was confirmed by a higher fiber friction force measured by the LFM. The extent of water contact angle decrease, as well as the wash fastness of the treatment varied with the structure of the textile. Indeed the more porous the textile structure is (such as a non-woven), the fewer are the chain scissions of the PET at the fiber surface, during the plasma treatment. Thus, the level of surface oxidation and the weak boundary layers formation depend not only on plasma treatment parameters but also on the textile structure.     

Water Purification by Membrane Distillation Process

Abstract

The demineralization of water by membrane distillation (MD) has been investigated. In the first stage of investigations the tap water or boiled tap water was employed as a feed, and the water recovery coefficient exceeding 75% was achieved. The obtained concentrate was supplied to the second stage of MD installation. The quality of distillate was stable and practically independent of the feed concentration. The produced distillate has the electrical conductivity in the range of 1.4–2.5 µS/cm. The precipitation of salt deposit on the membrane surface was observed during the water demineralisation, especially in the first stage of MD. The membrane morphology and the composition of precipitate layer were studied using scanning electron microscopy coupled with energy dispersion spectrometry. The formed deposit caused clogging of the membrane surface (pores), and resulted in a gradual decline of the module efficiency. Moreover, the formation of the deposit on the membrane surface was the major reason of the partial membrane wettability.     

Sugar cane juice concentration via CO2 gas hydrate formation

Sugar cane juice concentration via evaporation is the traditional method, though the downside in this technique is the product loss due to sucrose inversion. Gas hydrate separation is an emerging technology applied in desalination, carbon capture, and in this study, for concentrating fruit juice by trapping the water in the form of crystalline cages. A 750 cm³ hydrate reactor was used for hydrate formation experiments to concentrate the sugar cane juice, with a sampling of the concentrate to determine the final solids content. Hydrate formation experiments showed the successful concentration of a 0.12 mass fraction feed to approximately 0.56 mass fraction using four batchwise concentration stages. A comparison of the energy usage between the evaporation train as used in sugar factories and a single batch hydrate formation stage, to concentrate a 0.12 mass fraction feed to 0.30 mass fraction showed an energy reduction of approximately 20% for the hydrate method.     

UV-curable PDMS-containing PU system for hydrophobic textile surface treatment

Polydimethylsiloxane (PDMS) is a super-hydrophobic material with low surface energy. UV-curable PDMS-containing polyurethane (PU) oligomer (UV-PDMS-PU), having a PDMS moiety is designed for textile (PET and Nylon) surface treatment with a long lasting hydrophobic property. UV-PDMS-PU was prepared by an addition of 2-hydroxyethyl methacrylate (2-HEMA) to NCO-terminated PDMS-containing PU pre-polymer (NCO-PDMS-PU). NCO-PDMS-PU was obtained from an addition reaction of alkyl hydroxyl-terminated PDMS with an excess amount of isophorone diisocyanate (IPDI). UV-PDMS-PU system consisted of 1% (w/w) photo-initiator that was coated either on glass plate or textile and then cured by UV-radiation. The UV-cured PDMS-containing PU films were evaluated by the measurements of thermal and physical properties. The hydrophobic characters and silicone content were remained on textile surface after water washing cycles, which indicating that UV-curing process can help the PDMS moiety to anchor onto textile fibers.     

Effect of applied voltage on surface and volume charge density of the jet in electrospinning of polyacrylonitrile solutions

To investigate the effect of applied voltage on jet charge density, one must investigate its effect on the jet electric current and flow rate. However, there are some difficulties in measuring the jet flow rate. Here, the electrospinning jet flow rate is calculated by applying a new method and the effects of applied voltage and feed rate on jet charge density are investigated. The jet flow rate was independent of the feed rate and increased on increasing the applied voltage. By defining an experimental equation for dependence of jet flow rate on jet current, a relation between jet volume charge density and jet current could be defined. By measuring the electrospun fiber diameter, surface charge density of the jet could be estimated. On increasing the voltage, the jet volume charge density decreased whereas the jet surface charge density remained unchanged. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Characteristics of a recuperative heat exchanger with a textile heat-transfer surface

The heat transfer coefficients in laminar flow of water in a recuperative heat exchanger with a textile heat-exchange surface were experimentally studied. The method of measurement is described and the experimental data are reported. It is shown that convective heat exchange as the liquid moves in the textile channels is significantly enhanced due to the discrete roughness of the fabric.     

Experimental validation of hybrid distillation‐vapor permeation process for energy efficient ethanol–water separation

BACKGROUND: The energy demand of distillation‐based systems for ethanol recovery and dehydration can be significant, particularly for dilute solutions. An alternative separation process integrating vapor stripping with a vapor compression step and a vapor permeation membrane separation step, termed membrane assisted vapor stripping (MAVS), has been proposed. The hydrophilic membrane separates the ethanol–water vapor into water‐rich permeate and ethanol‐enriched retentate vapor streams from which latent and sensible heat can be recovered. The objective of this work was to demonstrate experimentally the performance of a MAVS system and to compare the observed performance with chemical process simulation results using a 5 wt% ethanol aqueous feed stream as the benchmark. RESULTS: Performance of the steam stripping column alone was consistent with chemical process simulations of a stripping tower with six stages of vapor liquid equilibria (VLE). The overhead vapor from the stripper contained about 40 wt% ethanol and required 6.0 MJ of fuel‐equivalent energy per kg of ethanol recovered in the concentrate. Introduction of the vapor compressor and membrane separation unit and recovery of heat from both membrane permeate and retentate streams resulted in a retentate ethanol concentrate containing ca 80 wt% ethanol, but requiring only 2.2 MJ fuel kg^?1 ethanol, significantly less than steam stripping alone. CONCLUSION: Performance of the experimental unit with a 5 wt% ethanol feed liquid corroborated chemical process simulation predictions for the energy requirement of the MAVS system, demonstrating a 63% reduction in the fuel‐equivalent energy requirement for MAVS compared with conventional steam stripping or distillation. Published 2009 by John Wiley & Sons, Ltd.     

Surface Modification of Polymer Textiles by Thermally Dried Ozone

Surface modification of polymer textiles by thermally dried ozone (O₃) was investigated for wool, cotton, raw silk, polyester and nylon textiles. Gaseous dried O₃, which was produced using silent discharge ozonizers from oxygen gas, was used in order to treat polymer textile surfaces. The ozone concentration was 2100 ppm (w/v) (9.5 × 10^?5 mol/l). It was noted that the treatment effectiveness of the textile with O₃ increased with temperature of the gas. Surface morphology of the treated textiles was observed with a scanning electron microscope. The O₃ modification process at 70°C altered the surface roughness of textiles, especially the morphology of wool textile showed that the ozonolysis process etched the wool textile surface. The surface wettability of each textile was tested with water contact angles before and after the treatment. The data showed that hydrophilic nature of the treated textile was significantly enhanced after the treatment. In the case of wool textile, the ozonolysis process at 70°C also altered the cuticle structure on the textile surface. The textile treated with O₃ at 70°C showed no shrinkage by water washing of the textile. Thus, it can be concluded that this method is useful to obtain shrink-resistant wool.     

Dendrimer finishing influence on CO/PES blended fabrics color assessment

Textile finishing includes all processes that help to maintain the value or increase the value of the textile material. It encompasses dyeing, printing, and all the finishing treatments to realize durable press, soil release, flame retardant, antistatic, antimicrobial, or water/oil repellency properties. When these properties are realized on dyed textile fabric, one effect could be ascribed to the color change induced by finishing operations. This research focuses on the assessment of color alterations occurring on the dyed cotton/polyester blended fabrics due to the nanoparticle‐sized dendrimer (DWR), dendrimer–fluorocarbon (DWOR), and fluorocarbon (FWOR) finishing onto their surfaces. The dependence of color on the surface state of treated textiles is calculated in the context of spectrophotometric measurements. Modification of the surface roughness by reflectance spectrum and the absorbance of finishes in visible range were investigated to determine color changes between the original (control fabric, dyed but not treated) and treated fabrics. As a result of color matching calculated by CIE‐Lab values, color change is related to the surface roughness associated with absorbance values of applied finishes. In addition, fabrics mechanical properties were evaluated to estimate if finishing agents application gives rise to other changes, besides color alterations. The fabrics mechanical properties have been found not significantly altered by the aforementioned finishing treatments. These results could be applied for industrial needs (quality control), or in the artistic field of conservation, or restoration (to follow the color of paintings). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Size segregation of spherical nickel pellets in the surface flow of a packed bed: Experiments and Discrete Element Method simulations

The size segregation of binary mixtures of spherical nickel pellets flowing into a packed bed was investigated with Discrete Element Method (DEM) simulations and physical experiments in 30 cm and 60 cm wide rectangular test cells. Each test cell approximates a vertical slice of a cylindrical packed bed, with a rising feed tube on one side of the cell representing the stationary frame of reference in the packed bed. As the feed tube is raised, the pellets flow laterally into the test cell to form a sloping surface inclined to the horizontal by the angle of repose. The lateral flow of pellets is confined near the surface of the packed bed, and was intermittent in character (i.e. surging). Velocity vectors show the detailed flow field in the simulated test cells. The smaller pellets were found to be concentrated near the core of the granular assembly, and the larger pellets segregate to the outer wall farthest from the feed tube. The degree of segregation, or coefficient of variation (variance/mean), is proportional to the diameter ratio α of the pellets and the length of the surface, and inversely proportional to the mass fraction of the smaller pellets within the range of parameters studied. The DEM simulations had an average deviation in mass fraction of 0.07 and maximum deviation of 0.22 from the experimental data.     

Concentration and separation of glycyrrhizic acid by foam separation

By the aid of the surface activities of glycyrrhizic acid, foam separation can be used to extract and concentrate it. The effects of operating parameters such as flow rate of air, initial feed concentration, pH and ionic strength on the enrichment ratio and recovery yield of glycyrrhizic acid are investigated in detail. In addition, the influences of other surface‐active substances in solution, such as proteins, on the separation of glycyrrhizic acid are also discussed. The experimental results show that foam separation is a simple and effective method to separate and concentrate glycyrrhizic acid. © 2002 Society of Chemical Industry     

Application of hydrophilic finished of synthetic fabrics coated with CMC/acrylic acid cured by electron beam irradiation in the removal of metal cations from aqueous solutions

Modified textile fabrics were used to remove Cu⁺² and Cr⁺³ ions from aqueous solutions. For this purpose, modified Nylon‐6, polyester woven and knitted fabrics were prepared by coating the surface with a thin layer of aqueous solution of carboxymethyl cellulose (CMC) and acrylic acid (AAc) of thickness 25 μm. Radiation crosslinking of the coated layer was carried out by electron beam irradiation with a constant dose of 30 kGy. Morphology of the coated fabrics was examined by scanning electron microscope (SEM) which indicated the compatibility between the coated layer and fabrics. Properties attributed to the hydrophilicity, especially water uptake and weight loss before and after several washing cycles were followed up. The effect of AAc concentration on the hydrophilic properties of the coated fabrics was studied. A considerable enhancement in water uptake has been attained on increasing AAc content in solution in case of nylon‐6 followed by polyester woven followed by polyester knitted fabrics. The performances of the modified textile fabrics were evaluated for the recovery of Cu⁺² and Cr⁺³ from aqueous solution. The metal ion absorption efficiency of the modified textile fabrics was measured using UV Spectrophotometer analysis and EDX. Parameters affecting the efficiency of these textile fabrics in the removal of metal ions from aqueous solution namely, concentration of AAc and the immersion time were studied. It was found that there was a marked increase in the recovery of metal ions on increasing both immersion time and concentration of AAc. This study evidences that the modified textile fabrics can be used for the purpose of removal of some heavy metals such as Cu and Cr. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nanofiltration of textile wastewater for water reuse

The textile industry produces a large amount of wastewater that is highly coloured with high loading of inorganic salt. Crossflow nanofiltration using thin film composite polysulfone membrane was used to recover the electrolyte solution and reject the colour. Using a synthetic textile effluent of reactive dye and NaCl solution, the study focused on the mechanism controlling flux and rejection by varying four main parameter; crossflow velocity, initial dye concentration, feed pressure, and electrolyte concentration. Results show that flux was dominated by the osmotic pressure created from the presence of NaCl, and that dye concentration did not significantly effect the flux or rejection. Working at low pressures of up to 500 kPa, relatively high fluxes were obtained, with an average dye rejection of 98% and NaCl rejections of less than 14%. Thus, a high quality of reuse water could be recovered. Even after a number of cycles, the membrane did not foul irreversibly, with an overall mean waterflux recovery of 99%.     

Investigation of cake deposition on various parts of the surface of microfiltration membrane due to fouling

The accumulation of deposited layer on membrane surface in cross-flow microfiltration was investigated. This study provides a basis for elucidation of the membrane segments with superior tendency for cake deposition due to fouling. A commercially available GVWP membrane was fouled with a colored (blue indigo suspension in water) feed. The deposition pattern or fouling tendency was obtained using a digital camera, scanning electron microscope (SEM) and image analysis. The effects of feed concentration, transmembrane pressure and cross-flow velocity on cake deposition were investigated. In the early stages of the filtration trials, cake deposition was increased from the commencement portion (feed inlet) towards the furthermost part (concentrate outlet) of the membrane surface. However, at the completion of filtration, no pronounced difference was realized between cake deposition in the median and end parts of the membrane. Computational fluid dynamics (CFD) modeling of the membrane was carried out to predict the fouling behavior in various segments of the membrane at different operating conditions. The results of CFD modeling are in acceptable agreement with the experimental data. Accomplishment of the membrane sections with higher tendency for accumulation of foulants may provide a basis for manipulation of conditions to diminish the buildup of fouling deposition in the proposed segments. This results in lower cake deposition on vital parts to minimize the overall fouling.     

SIMULATION OF WATER TRANSFER IN SPRAY DRYING

A drying method by desorption in a water activity meter (Aw-meter) was used to simulate the conditions of spray drying and to determine the water transfer inside the dairy concentrate to the surface (first transfer) and from the surface to the drying air (second transfer). A limitation in the first transfer decreased the second transfer. The percentage of bound or unbound water was determined as a function of the nature of concentrates (milk concentrate, high protein milk concentrate, native casein suspension, caseinate dispersion, ) before drying. The water transfer in the different dairy concentrates during drying was shown as a function of the environment of their water content and the nature of the constituents. The percentage of bound or unbound water and the drying behavior of any dairy concentrate could be determined in 4 to 6 hours and might predict spray drying behavior in an industrial tower.     

Coupling of nanofiltration with microfiltration and membrane bioreactor for textile effluent reclamation

This work investigates the application of a microfiltration–membrane bioreactor–nanofiltration hybrid process for textile effluent reclamation. The indigo blue dye was efficiently retained by the microfiltration membrane (100%), which allows its recovery from the concentrate stream. The membrane bioreactor resulted in chemical oxygen demand (COD) and ammonia removal of 73% and 100%, respectively. Nanofiltration technology was successfully applied to polish textile effluent. The principal cause of flux decline was determined to be concentration polarization. The nanofiltration permeate meets the quality requirements for all processes within the textile industry, while the nanofiltration concentrate can be used for less demanding purposes.     

Thermal and morphological stability of polystyrene microcapsules containing phase‐change materials

Polystyrene microcapsules with paraffin wax as the active agent [phase‐change material (PCM)] were produced by a Shirasu porous glass emulsification technique and a subsequent suspension‐like polymerization process. The suitability of the obtained microcapsules for textile applications was studied. The thermal properties, surface morphology, and structural stability of the PCM microcapsules were investigated with differential scanning calorimetry, thermogravimetric analysis, and environmental scanning electron microscopy. The microcapsules could be used without any appreciable damage or irreversible changes in their integrity until 135°C. Furthermore, these microcapsules were heat‐resistant and could endure the curing conditions of textile coating up to 140°C for 30 min. In addition, the stability of the microcapsules under common laundering conditions was tested. It was confirmed that the microcapsules were durable enough and maintained their stability during stirring in hot water and alkaline solutions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

过氧化尿素的合成及应用研究进展

综述了过氧化尿素的性质及其合成方法,过氧化尿素的合成主要有湿法和干法两种工艺,目前常用的为湿法工艺。过氧化尿素具有活性氧含量高、水中稳定性高等特点,广泛用于农业、医药、纺织、日用化工、食品、养殖、饲料、印染等许多领域,过氧化尿素有巨大的发展潜力。