THE DEHYDRATION OF THE LOWER FATTY ACIDS BY EXTRACTIVE DISTILLATION

The lower fatty acids cannot be readily separated from water by distillation. Formic acid forms a maximum azeotrope with water, acetic acid boils very close to water and propionic acid forms a minimum azeotrope with water. These acids can be easily separated from water by extractive distillation. Effective agents for each dehydration are presented.     

Desalination and water recycling by air gap membrane distillation

Membrane distillation (MD) is an emerging technology for desalination. Membrane distillation differs from other membrane technologies in that the driving force for desalination is the difference in vapour pressure of water across the membrane, rather than total pressure. The membranes for MD are hydrophobic, which allows water vapour (but not liquid water) to pass. The vapour pressure gradient is created by heating the source water, thereby elevating its vapour pressure. The major energy requirement is for low-grade thermal energy. It is expected that the total costs for drinking water with membrane distillation will be lower than $0.50/m³, even as low as $0.26/m³, depending on the source of the thermal energy required for the evaporation of water through the membrane.     

Industrial Water Desalination by Vacuum Multi‐Effect Membrane Distillation

Water shortage and a rising water demand are prevalent issues on the political agenda worldwide. Available water resources must not only be provided to ensure a domestic and drinking water supply for a steadily increasing population but also for the growing industrial and agricultural sectors. This work outlines how the use of the innovative vacuum multi‐effect membrane distillation contributes to improve the water management efficiency in the following key industry sectors: desalination, drinking water and beverage industry, pharmaceutical, agro and chemical as well as oil and gas industry.     

Electrolytic deposition for scale control in sea water distillation

This paper describes laboratory experiments on the electrolytic deposition of scaling compounds from sea water. The dependence on applied current, time of deposition and the effect of sea water stirring is studied. X-ray diffraction patterns of scales are taken to confirm their composition. The pH changes of the sea water feed occurring during the experiments under varying currents are investigated. The possible application of these studies in controlling alkaline scale is suggested. The feasibility of using electro-deposition as a means for controlling alkaline as well as calcium sulfate scales in seawater distillation plants has been ascertained.     

Five years operating experience of large scale distillation test plant made of carbon steel

The distillation test plant operated since April 14, 1972 during 94.2% of the work day has the capacity to treat 1,000 cu. meter/day of sea water, to produce 850t of fresh water of excellent quality, leaving 150t of concentrated brine containing 20% solid matter. Raw sea water was pretreated to prevent scale formation and corrosion of materials in distillation. Patents have been granted in Japan, USA, United Kingdom, West Germany, France, Italy, etc. (1).This method enables use of a base metal such as common steel for construction with the following advantages:Capital investment is cheaper.No galvanic corrosion arises.Mechanical structure is rigid.Contamination of poisonous heavy metals is avoidable.Upper limit of temperature is higher.Amount of raw sea water is smaller.Amount of exhaust brine is smaller.     

THE BREAKING OF TERNARY ACETATE-ALCOHOL-WATER AZEOTROPES BY EXTRACTIVE DISTILLATION

The breaking of seven ternary acetate-alcohol-water azeotropes by extractive distillation was accomplished. They are n-propyl acetate-n-propanol-water, isopropyl acetate-isopropanol-water, n-butyl acetate-n-butanol-water, 2-butyl acetate-2-butanol-water, isobutyl acetate-isobutanol-water, n-amyl acetate-n-amyl alcohol-water and n-hexyl acetate-n-hexanol-water. The acetates, usually the highest boiling constituents, are obtained as overhead product as a two-phase mixture with water. The most effective agents are glycols and dimethylsulfoxide. Solubility parameters were found to be a qualitative indication for selecting extractive distillation agents. When the formation of a chemical complex is dominant, solubility parameter does not explain solution behavior satisfactorily.     

膜蒸馏技术的应用和发展

膜蒸馏是 2 0世纪八十年代才引起人们重视的新型膜分离技术。本文主要对膜蒸馏的过程机理、影响因素、用膜材料进行了讨论 ,同时介绍了膜蒸馏在海水淡化、水溶液的分离与浓缩、工业废水的治理等中的应用 ,并在此基础上提出了膜蒸馏的发展方向     

Klimaschonung durch Membrananwendung – Membrandestillation zur Erzeugung von pharmazeutischem Reinstwasser

Water is the most important medium in the pharmaceutical industry. The required water quality depends on the intended purpose and this in turn influences the effort involved in water treatment. Today, the production of pure water for use in the pharmaceutical industry is mainly based on multistage distillation and membrane processes, especially the combination of reverse osmosis, electrodeionization and ultrafiltration. Membrane distillation (MD) as a relatively new method is an alternative to these classic methods of pure and ultrapure water production. The treatment of pharmaceutical water from drinking water with the help of MD is presented. More specifically, the focus is on the suitability for pharmaceutical water treatment, the effect of different process parameters on the performance, and the possibility to reduce the specific energy demand.     

Desalination in the gaza strip: drinking water supply and environmental impact

More than 90% of the population of the Gaza Strip depends on desalinated water for drinking purposes. About 90% of the groundwater is unacceptable for drinking as a result of contamination by nitrate and chloride. One of the major options for resolving the water problems is the utilization of desalination technology for both sea and brackish water. The objective of this article is to address desalination water management in its embryonic stage in the Gaza Strip. The sources of drinking water supply, distribution system and the environmental impact of brine water will be fingered in detail. Desalination facilities range from large seawater plants to small brackish desalination units on a home scale. Governmental, non-governmental and private desalination plants are common. The distribution system of desalinated water is a responsibility of governmental, non-governmental, private small community bodies and even individuals. Disposal of brine water is made either directly or indirectly into the sea, sewage system, poor land, channels, wadies, etc. Brine constituents have an adverse impacton the surrounding environment, e.g., sea life, soil, wastewater treatment plants and the groundwateraquifer. The lack of real environmental impact assessments, especially for mid- and home-scale units may lead to a deterioration of the environment. The fragmentation of the responsibilities of water desalination, distribution of desalinated water and the disposal of brine water suggest that urgent action should be taken (e.g., legislation or establishment of a supervisory body). In other words, strict policies and management actions are to be taken in order to alleviate the health and environmental impact of an important and uncontrolled new system.     

The water problem in egypt

Egypt faces the prospect of rapid growth of populatlon which is a vital problem since agricultural land is not available at the same rate. More land should be reclaimed through development of water resources.The Nile river constitutes an immense water supply but one third of its water is lost through pumping low salinity drainage water to the Mediterranean Sea utilizing costly electric power. Therefore, feasibility studies on recycling this water must be carried out.Along the banks of the Nile, drinking water could be obtained supplied through either small water purification plants or electrodialysis desalination plants, and the economics of the two methods should be compared before deciding on either method.Another source is underground water with a salinity varying between 2000 and 11,000 ppm. For such brackish water, either the electrodialysis or reverse osmosis process can be used.Then there is the Egyptian sea shore which extends over 3000 km. and where the salinity of the sea varies between 33,000 and 45,000 ppm. Here flash distillation processes are suitable.The present paper briefly describes available water resources in Egypt and discusses possible solutions to supplying the fresh water required in different areas.The present investigation concentrates on the feasibility and economics of utilizing the electric supply from the grid at periods other than the peak loads for operating electrodialysis plants. It is estimated that a series of electrodialysis plantsrunning for lOh/day would provide 2.6 million m³/day at an operating cost of 10¢/m³ in addition to capital costs.     

Some aspects of laboratory studies on alkaline scales

Laboratory studies on formation of alkaline scales are reported. Preliminary investigations relating to the dependence of alkaline scales, arising in sea water evaporation, on the surface of heat transfer, time of contact, heat flux, sea water turbulence and the effect of CO₂ environment are presented. It is suggested that the utilisation of laboratory data to infer the actual extent of scaling in sea water distillation plants requires careful consideration.     

Vapor-liquid equilibria of some pollutants in aqueous and saline solutions Part I: experimental results

Vapor-liquid equilibria were measured for dilute aqueous solutions of formic acid, acetic acid, pyridine, aniline, isobutyl alcohol, isoamyl alcohol, n-butyl acetate, dimethyl phthalate, diethyl phthalate and dioxane, respectively, at various pH, temperatures and concentrations of sodium chloride.The substances chosen are very important raw materials or intermediates in chemical industry and are widely used. Phthalates are used as plasticizers and leach, in small amounts, into water from plastics. Recently in Japan, we are recognizing phthalates as a new polluting material in sea water and river water.The vapor-liquid equilibria were severely affected by the pH of the solution, not only for the electrolytes (such as formic acid and pyridine), but also for esters. This is probably due to the effect of pH on the degree of the dissociation of electrolytes and on the hydrolysis of esters. The phase equilibria of some organic materials which are less soluble in water (such as phthalates and higher alcohols) were greatly affected by the salting-out effect of salinity.If the feed sea water to distillation plants is contaminated by volatile organic materials, some of them concentrate in the distilled water. Therefore, attention must be given to the properties of volatile, polluting materials in sea water when the product water from desalination processes is for human consumption.     

蒸气顶空富集装置-自动顶空气相色谱法在海水中痕量苯系物检测中的应用

采用蒸气顶空富集-自动顶空气相色谱法,研究了海水中痕量苯系物(包括苯、甲苯、乙苯、对二甲苯、间二甲苯、邻二甲苯和苯乙烯)的测定方法,优化了蒸气富集作为海水中苯系物预处理方法的参数。对其精馏管长度、回收冷凝液体积、吸收介质等影响富集效果的关键因素进行了评价,并优化了色谱条件,考察方法的精密度和回收率。结果表明,大体积水样经过10 cm长度冷凝管的二次冷凝富集,以水作为吸收剂,1 L水样富集浓缩至10 mL后,可使原有自动顶空气相色谱分析苯系物的灵敏度提高1~2个数量级。采用蒸气顶空富集-顶空气相色谱法测定海水中的苯系物的平均加标回收率为83%~113%,相对标准偏差为1.1%~5.4%(n=3);苯系物的海水中检出限为0.02~0.1μg/L。本文建立的蒸气顶空富集-自动顶空气相色谱法简单快速,重现性好,回收率高,适用于海水中痕量苯系物的分析测定。     

A new process for the extraction of water from air

An experiment to extract water from wet air has been realised. The experimental results indicate that the typical S-shaped isotherms of our composite material are analogous to the data obtained by adsorption of water vapor on various mineral adsorbents. The solar distillation is accomplished by heating the wet composite material by solar irradiation. Evaporation and condensation produce at the end of the cycle one liter of drinking water per square meter of composite material.     

水中硼的去除方法研究进展

硼广泛应用于现代工业的各个领域,随之而来的含硼废水也开始引起人们的关注。苦咸水和海水由于硼含量较高,作为饮用水或灌溉水之前必须进行除硼处理。水中硼的去除方法逐渐成为人们关注和研究的热点之一。概述了硼的相关环境标准及水中硼的去除方法,分析了各种方法的优缺点,探讨了除硼方法的发展趋势。     

Moderne voltammetrische Verfahren in der Spurechemie toxischer Metalle in Trinkwasser,Regen- und Meerwasser

Modern voltammetric methods in trace chemistry of toxic metals in drinking water, rainwater and seawater . In environmental research and protection, toxic metals (particularly Cd, Pb and Hg) are becoming increasingly significant owing their biological nondegradability and the chronic toxicity resulting from their accumulation in vital organs of man. Aquatic systems, such as the sea, inland waters, drinking water, rainwater etc., are important stages in the biogeochemical cycle. Although the dissolved levels are usually in the trace range of μg/1 to ng/1 they still remain significant, because their entry into the food chain and interactions with suspended particulates and sedimnts largely occur via the dissolved state. General comparative considerations suggest modern voltammetric methods, particularly differential pulse stripping voltammetry (DPSV), to be the most promising choice for the determination and characterization of dissolved toxic heavy metal traces. Voltammetry combines extreme sensitivity with high inherent reliability, good precision, scope for simultaneous determination of several metals and modest costs. Moreover, due to its substance specificity, voltammetry permits identification and physicochemical characterization of dissolved complexes and chelates. The striking and comprehensive scope of voltammetry in trace metal chemistry of aquatic ecosystems is illustrated by examples from drinking water control, investigations on rainwater, extended studies in European coastal waters and the oceans, and by fundamental work on the occurrence and behaviour of toxic trace metal species in the sea.     

Energy and exergy analyses of seawater desalination system integrated in a solar heat transformer

Among the numerous options to improve the energy efficiency of desalination plants stands out the absorption heat transformer. A heat transformer is a device, which can deliver heat at a higher temperature than the temperature of the fluid by which it is fed. Solar thermal energy can be used as heat input for single effect heat transformer while the high grade thermal energy delivered by the heat transformer can be used as heat source for water desalination.In this paper, an attempt has been made to study the combination: flat plate solar collectors, a single effect heat transformer and desalination system (distillation process) used to provide a beach house located in Skikda (East of Algeria; Latitude 36.52°N, Longitude 6.57°E) with drinking water. This system produces about 500 l of drinking water per day in July.Mathematical models of the solar flat plate collectors (FPC), absorption heat transformer (AHT) operating with the water/lithium bromide solution and the overall desalination system (WP) were developed to simulate the performance of this combination system. The energy and exergy analyses are carried out for each component of the system. All exergy losses that exist in this solar desalination system are calculated. Energy and exergy efficiencies are estimated.     

Distillation vs. membrane filtration: overview of process evolutions in seawater desalination

The worldwide need for fresh water requires more and more plants for the treatment of non-conventional water sources. During the last decades, seawater has become an important source of fresh water in many arid regions. The traditional desalination processes [reverse osmosis (RO), multi stage flash (MSF), multi effect distillation (MED), electrodialysis (ED)] have evoluated to reliable and established processes; current research focuses on process improvements in view of a lower cost and a more environmentally friendly operation. This paper provides an overview of recent process improvements in seawater desalination using RO, MSF, MED and ED. Important topics that are discussed include the use of alternative energy sources (wind energy, solar energy, nuclear energy) for RO or distillation processes, and the impact of the different desalination process on the environment; the implementation of hybrid processes in seawater desalination; pretreatment of desalination plants by pressure driven membrane processes (microfiltration, ultrafiltration and nanofiltration) compared to chemical pretreatment; new materials to prevent corrosion in distillation processes; and the prevention of fouling in reverse osmosis units. These improvements contribute to the cost effectiveness of the desalination process, and ensure a sustainable production of drinking water on long terms in regions with limited reserves of fresh water.     

非乳液型丙烯酸酯水分散液的研制

丙烯酸酯和定量的不饱和羧酸先在非水溶剂中聚合，然后以氨中和，经蒸馏加水等可制得非乳液型丙烯酸酯水分散液。单体中羧酸的含量是使聚合物兼具水溶性和耐水性的关键．阐述了合成丙烯酸酯水分散液的各因素—溶剂、单体、交联剂、聚合温度、中和和蒸馏等。     

Calcium sulfate hemihydrate scaling threshold enhancement by magnesium ion augmentation

Efficient high temperature distillation of sea water cannot be realized without development of scale control systems for calcium sulfate. This paper describes a new concept of scaling threshold enhancement based on complexing a portion of dissolved sulfate ion in the form of stable MgSO^o ion pairs. Complexing may be accomplished by augmentation of feed water with magnesium ion recovered and recycled from distilling plant blowdown. This “tying up” of sulfate ion results in higher solubility levels of calcium sulfate. Magnesium ion augmentation at levels up to three times ambient results in markedly improved resistance to hemihydrate scaling in natural sea water. Significantly higher levels of operating temperature and concentration factor may be achieved by this technology.