超滤系统的在线化学清洗

对榆次恒能热电有限公司超滤系统污堵产生的原因进行分析,针对其特点对超滤系统进行了化学清洗,清洗效果良好,为确保系统的安全稳定运行,并对该超滤系统的运行进行了改进与探讨。     

Layer-by-layer self-assembly of multifunctional enzymatic UF membranes

In order to eliminate membrane fouling and to ensure enzymatic hydrolysis of urea, multifunctional biocatalytic membranes were prepared by using urease (URE) and trypsin (TRY) enzymes on the sulfonated polysulfone (SPSf) ultrafiltration membrane via layer-by-layer (LbL) self-assembly method. The membrane architecture consisted of multilayer assembly with TRY and URE enzymes as the outer layer and inner sandwiched layer, respectively. Polyethyleneimine (PEI) and alginate (ALG) were used as cationic and anionic polyelectrolytes. Sulfonation and PEI deposition were successfully accomplished as confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy analysis, contact angle measurements, staining with toluidine blue and Congo red dyes and dead-end filtration experiments. A characteristic value of SPSf membrane with a high water permeability (1000 L/m².h.bar) and 95% bovine serum albumin (BSA) rejection was observed. In static conditions, URE activities of SPSf2-PEI-URE membrane were not affected by BSA fouling, while TRY immobilizations with increased concentrations (SPSf2-PEI-URE-PEI-ALG-TRY) significantly lowered the activity of URE. In dynamic conditions, each deposited layer exhibited individual resistance to flow that can be considered as irreversible fouling and caused 90% of flux decline for the SPSf2-PEI-URE-PEI-ALG-TRY membrane assembly. The recovery of the initial flux for the multilayered membrane at the end of six fouling and washing cycles was observed 85%. Moreover, at the end of 5 cycles, 78% of the URE initial activity of the multilayered membrane was preserved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48750.     

反渗透膜的清洗

介绍了反渗透设备在应用中遇到的膜污染问题、清洗方案的制定及实施清洗后取得的良好效果。     

食品饮料行业微滤、超滤、反渗透膜的清洗

本文介绍了食品饮料行业膜过滤装置及配件的清洗     

Ultrafiltration of macromolecular solutions with high-flux membranes

Batch and flow recirculation cells were used to study the properties of high-flux ultrafiltration membranes with different macromolecular solutions. At low pressures, solutions of completely retained macromolecular solutes have a flux which is approximately the same as the flux of pure solvent. At higher pressures, the solution flux levels off. The flux, at the leveling-off period, is approximately inversely proportional to the solution concentration. In this plateau region the flux increases with temperature and agitation of the solution but decreases with time. These results are explained by the formation of a gel layer on the membrane surface during the filtration of macromolecular solutions. In ultrafiltration, in contrast to dialysis and GPC, a linear polymer penetrates the selective barrier more readily than does a globular protein of the same molecular weight. The difference may arise from the liquid shear stresses within the barrier medium due to the movement of fluid relative to the pore walls, which is large only in ultrafiltration. Also, retention of polymers was found to decrease with pressure and to increase with agitation of the solution.     

Processing of black liquors by UF/NF ceramic membranes

This study deals with the treatment of black liquor from wood pulping by means of membranes. UF/NFmembranes with a skin layer of TiO₂ and ZrO₂ have been applied to recover water and to concentrate the residual effluent. Three different membranes with molecular weight cut-off of 1, 5 and 15 kDa have been checked. The membranes have been tested either in single stage operation or in cascade. Total dissolved solids, organic matter, organic to mineral matter ratio and ash have been determined. In addition, chemical oxygen demand (COD) retention was calculated by measuring in the feed solution as well as in the permeate and in the concentrated solution. During the concentration step the steady state was reached after a few minutes running. There was not significant change in the permeate flow until the volume was reduced at half. Only the 15,000 Da membrane showed continuous permeate flow declining. Regardless the membrane used, dry matter, organic matter and COD analyses showed that the retention of organic substances fell in the range of 60-70%, depending on the conditions selected.     

Cleaning of fouled ultrafiltration (UF) membrane by algae during reservoir water treatment

Ultrafiltration (UF) membrane fouling is often encountered in water treatment. Algae could be removed by UF membrane for its nominal pore size, and the algae cells deposited on the surface of UF membrane. The cells attach to the membrane, they start to release secretion and produce extracellular polymetric substances (EPS), which accumulate on the surface and cause the flux decline. This study examined the effects of hydraulic and chemical cleaning on fouled membrane by algae-rich reservoir water. Four kinds of hydraulic cleaning method were investigated, including forward flushing, backwashing, forward flushing followed by backwashing and backwashing followed by forward flushing. Backwashing followed by forward flushing was more effective for flux recovery, and 20 min duration were enough for the cleaning. To maximize flux recovery for the algae-fouled membrane, chemical cleaning was applied as enhanced cleaning strategies. NaOH, NaOCl, and citric acid were used for cleaning agents. The cleaning with the combination of NaOH (0.02 N) and NaOCl (100 mg/L) was effective than separate uses. And the cleaning duration was determined as 4 h.     

UF technology contributes to the recycling of dye salt solutions

Working in conjunction with an Indian textile manufacturer situated in the state of Tamil Nadu, the membrane filtration specialist Hydranautics has devised a new system that enables the recycling of the salt solution used in its dyes. The system was successfully tested in July of this year and is now in full operation at the processing plant, where it is helping to cut costs and save unnecessary waste. Hydranautics' role in the project involved designing an ultrafiltration (UF) system for the recycling process. The company selected its HYDRAcap® capillary membranes for the duty, which offers particulate removal down to 0.1 microns in size.     

Fabrication of PAN/PHCS adsorptive UF membranes with enhanced performance for dichlorophenol removal from water

A series of novel polyacrylonitrile (PAN) adsorptive UF membranes were prepared via the nonsolvent induced phase inversion method using adsorbent‐amphiphilic porous hollow carbonaceous microspheres (PHCSs) as additive. The resulted PAN/PHCS membranes were demonstrated to have better mechanical strength than the pure PAN membrane. The water fluxes of the PAN/PHCS membranes were slightly decrease; however, the rejections to pepsin were maintained at a high level (81–86%). The properties of the PAN/PHCS membranes for 2,4‐dichlorophenol removal from water were investigated. The results showed that 2,4‐dichlorophenol could be rapidly removed from water via adsorption mechanism by PAN/PHCS membranes, and the maximum reduction efficiency was up to 70%. The adsorption of 2,4‐dichlorophenol to the membranes was reversible and the membranes could be regenerated facilely by water washing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40837.     

Desalting of phenylalanine solutions by electrodialysis with ion-exchange membranes

This paper describes the optimization of the recovery of phenylalanine from an industrial waste stream by electrodialysis. An electrodialysis apparatus, consisting of three compartments equipped with ADP and CDS ion exchange membranes, was tested. These membranes without pretreatment appeared to be less efficient than the first pretreatment membranes which were immersed in a salt waste stream for 18h. The electrodialysis process with pretreated membranes yielded 87% of recovered phenylalanine. Furthermore, this process has also been successful in removing 98% of salts (Na₂SO₄ and (NH₄)₂SO₄), from the initial solution with an average current efficiency in the range of 96%. In the second pretreatment, the membranes were soaked in a bovine serum albumin solution for 2h before the commencement of the experiment. The results obtained show that the phenylalanine loss is significantly reduced. This loss did not exceed 5% and had an average current efficiency of 98%.     

Overview of theories for water and solute transport in9 UF/RO membranes

The applicability of various models for the transport of water and solute in UF/RO membranes is briefly outlined.The selectivity of various solutes in ultrafiltration and reverse osmosis is further discussed.     

陶瓷膜处理乳化悬浮液过程中的膜清洗工艺

对陶瓷膜处理乳化悬浮液过程中膜清洗工艺进行了研究。考察了清洗工艺如动态清洗、温度、清洗剂浓度、操作方式等对膜层清洗效果的影响,确定了适宜的清洗工艺参数。研究结果表明:用透过液或低浓度料液在常温下对污染膜进行清洗后,可使膜通量恢复达初始通量的96%以上;停止工作后的膜后处理工艺中,清洗剂浓度对清洗效果的影响不大,但应将清洗剂在高速流动状态下来清洗油污较为适宜。     

Enhanced modification technique for polyacrylonitrile UF membranes by direct hydrolysis in the immersion bath

Conventional hydrolysis modification of polyacrylonitrile (PAN) membranes is usually carried out in a post-treatment step during which hydrophilic groups are created on the membrane surface. In this article, however, direct hydrolysis in the immersion bath is proposed as a new and simple approach for simultaneous membrane preparation and modification. The main advantages of this method include lower alkali concentrations, promptness, and the lack of need for elevating temperature compared to other studies. The cast films were immersed in the coagulation bath containing aqueous NaOH solutions of various concentrations (0.003, 0.0125, 0.025, 0.05, and 0.1 M) for 1, 3, 5, and 10 min, which were then transferred to a bath of pure water. Membranes were characterized by pure water flux, porosity, average pore diameter, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, mechanical properties, rejection, and flux recovery ratio (FRR) measurements. At all treatment times, the pure water flux of modified membranes reached its maximum at low NaOH concentrations with a substantial increase (210%) in the membrane treated with 0.0125 M NaOH for 1 min. Furthermore, the kinetics of the hydrolysis reaction was considered to provide deeper insights into morphological changes occurring during the hydrolysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48583.     

Characteristics of permeation and separation of aqueous alcoholic solutions with chitosan derivative membranes

Permeation and separation characteristics for the feed vapours from aqueous alcoholic solutions through chitosan derivative membranes such as chitosan acetate (GA-ChitoA), chitosan (GA-Chito), and carboxymethyl chitosan acetate (GA-CM-ChitoA) membrane crosslinked with glutaraldehyde were investigated by evapomeation. The GA-Chito and GA-CM-ChitoA membranes prepared from casting solutions containing an optimum amount of glutaraldehyde showed a high permeation rate and high water permselectivity for an azeotropic composition in an aqueous ethanol solution. The permselectivity for water through the GA-CM-ChitoA membrane in evapomeation was in the order of aqueous solutions of methanol < ethanol < 1-propanol. The effect of the chemical and physical structure of these hydrophilic membranes on the permeation and separation characteristics is discussed.     

Bone china formulated with waste glass

Abstract

Abstract

Bone china is known for its technical and aesthetical quality with distinguishable whiteness, brightness and high mechanical strength. In this work, the use of waste glass was investigated in a bone china composition. This makes the production of this porcelain even more interesting from the environmental point of view, since most of its raw materials are from recyclable sources. Potash feldspar was partially replaced by waste glass, and the technical and slip rheological properties, phase development and microstructure after firing of the ceramic bodies were evaluated. The results revealed that waste glass provides a reduction in firing temperature and large plateau for firing while maintaining the quality of the final porcelain, including thermal expansion and mechanical strength.