Washing Processes for Disperse Particulate Systems – Process Spectrum and Aspects for the Process Choice

Washing of disperse solid systems is a widely used and complex operation. Since the washing step is mostly integrated into other process operations, it is subject to numerous demands exceeding by far the primary demands, like a good separation result and a low specific wash liquid demand. Because of the phenomenology and limits of different washing processes it is difficult to choose an appropriate washing process. Additionally, the acting transport mechanisms of some washing processes are not yet sufficiently understood. This work gives a broad overview of the existing washing processes, the numerous parameters, and the demands they have to meet. Based on a categorization of washing processes and the classification of these processes according to their macroscopic transport phenomena, an evaluation scheme has been developed which compares and assesses existing washing processes and shows their individual limits. The present work can be used as a rough guideline for the choice of an appropriate washing process.     

Wissenschaftliche Untersuchungen über die gesundheitliche Verträglichkeit enzymhaltiger Waschmittel

Scientific Investigations on the Tolerance of Enzyme-Containing Washing Agents Washing agents containing enzyme-additives appeared in the German market since 1966 on a wide scale. Today, in the entire western world, this type of detergent constitutes a considerable proportion (80%) of the total consumption of washing agents. In the present work based on experimental results, it is proved that enzyme-containing washing agents are not harmful to health. Test-procedures and results on the toxicity and irritation for these washing agents are reported for cutaneous application, and studies on skin-sensibilisation are described.     

Das Auswaschen von Filterkuchen

Washing of filter cakes . The demands placed on the purity of filter cakes exert a pronounced influence on investment and operating costs. Hence a careful study of the washing process is called for. On washing with a medium flowing through the cake it is possible to distinguish three regimes, viz. displacement, intermediate, and diffusional. The amount of washing liquid can be reduced by countercurrent operation, in several steps with repeated stirring of the cake in cases of extreme purity requirements. The washing results in an industrial plant are generally poorer than in the laboratory. The reasons for this discrepancy are more pronounced irregularities in the cake structure, cracking, or an inappropriate distribution of washing liquid.     

Gläser in der Geschirrspülmaschine I

Glasses in Dish Washing Machine I Efficiency of household dish washing machines, detergents and rinsing-aids has been considerably increased during the past years. A common problem is due to the diversity of articles to be washed. Even today, the behaviour of glasses causes some anxiety, because mechanical washing can lead to scratchy appearance and turbidities. These anomalies are mainly due to factors originating from the glass itself, although the external factors during the process of mechanical washing play a significant role as well. Results of investigations have shown that mechanical washing requires highly resistent glasses. The author has shown that it is possible to prepare standardized glasses that are required for such experiments. It is interesting to note that glasses certified as resistent a dish washing machines are already offered in the market.     

Über eine neue,praxisnahe Bestimmung der Aktivitäten von Waschmittelenzymen

A New Procedure for the Determination of Activity of Enzymes Used in Washing Agents The enzyme has become an integral part of a modern washing agent. The properties of such enzymes are determined by a suitable testing procedure, which leads to the application of these biologically active preparations under optimum conditions. In the present paper the mode of action of the enzyme preparations is described in short, followed by a critical consideration of the testing procedures which are currently employed. As a major topic a testing system especially suitable for the washing agent industry is chosen, which takes into account the important characteristics such as range of measurement, choice of substrate, concentration-, temperature- and pH-dependence, as well as the compatibility of the enzymes with other components of the washing agent. Two practical examples are given.     

Enzyme in Spülmitteln für Haushalt-Geschirrspülmaschinen? I

Enzymes in Washing Agents for Household Dish Washing Machines? I As early as in the beginning of this century, enzymes were used for the first time in tannery and laundry. At the end of the year 1969, when household dish washing machines provided with two cleaning operations per washing programme were available in the market, enzymes started gaining interest in the field of mechanical dish washing, since first of the aforesaid cleaning operations was meant for “biological cleaning”.     

Zur Kombination von Desinfektionsmitteln und Waschmitteln Anforderungen an die Wäschedesinfektion

Combination of Disinfectants and Washing Agents: Requirements for the Disinfection of Laundry The general use of disinfectants in common washing processes is not recommendable, since the complete effectiveness of a disinfectant is achieved only if it is used under controlled conditions. The Swiss Microbiological Society has recommended specifications on the requirements which should be fulfilled in various processes of disinfection. On this basis, the various requirements in the disinfection of laundry are explained. They include the elimination of undesirable germs, non-injurious action on material and surroundings, non-toxic nature, compatibility with other accompanying substances, flexibility in application, desirable chemical and physical properties, as well as usual periods of action.     

Über die Wechselwirkungen zwischen Blut und Sauerstoffbleichmitteln sowie über die Problematik von enzymatischen Vollwaschmitteln

Interaction between Blood and Oxygenating Bleaching Agents and Problems Involving Enzyme-Containing Washing Agents Haemoglobin catalyzes the decomposition of perborate during the action of washing agents on blood, thus leading to fixation of denaturated blood. The formation of cystine bridges alone does not explain this fixation. The splitting of H₂S followed by cross-linking in blood protein over the double bonds are considered by the author as important processes as well. Fixed blood can only be decomposed by prolonged action of proteases, enzymatic soaking in the absence of perborate being optimum. The injurious action of perborate on enzymes is not the determining factor in the difficulty encountered in the washing of some blood stains by enzymecontaining washing agents.     

Peroxycarbonsäuren - Neue Bleichwirkstoffsysteme für die Textilniedrigtemperaturwäsche

Peroxycarboxoic Acids - New Systems of Bleaching Substances for the Low Temperature Textile Washing. In the recent time the development of activ oxygen containing bleaching agents for the low temperature textile washing process was increased. Because of their properties peroxycarboxoic acids and preferably diperoxydodecandioic acid can be used in detergent formulations. The stabilization of peracids by in situ desensitization allows safe handling for the formulator as well as for the consumer.     

Transport processes during electrowashing of filter cakes

Applications of electric fields during washing of filter cakes increases the removal rate of ions from the cake mother liquor, and under appropriate conditions the field also increases the wash flow rate by electroosmosis. Experimental data that show the key effects of the fields on the rates of ion mass transfer are presented: with the downstream electrode acting as a cathode, cation removal rates are increased whilst the removal rate of the anions is decreased. The concentration profile of the cations with washing time shows an increase in concentration to a value above that of the mother liquor, before it decreases due to displacement by the fresh wash liquor. A model is formulated that describes the advection, dispersion, ion migration and electroosmosis transport processes in the cake. Numerical solution of the model gives cation concentration profiles at the exit of the cake that are in qualitative agreement with the experimental observations. Experimentally measured wash liquor flow rates tend to be lower than what traditional colloid science principles predict by a factor of 5-10: reasons for this difference, supported by experimental work from other researchers, are discussed.     

Dry action of Trichoderma reesei cellulases on cotton fabrics

Following treatment with Trichoderma reesei cellulases, the mechanical properties of cotton fabrics were measured to assess the effect of adsorbed enzymes. The ability of adsorbed cellulases to act as anchors for further wet finishing processes was studied. Dried fabric samples, after 105 days under usual storage conditions, showed neither significant strength loss, nor any changes in the degree of polymerisation. After five months of storage, the enzymes were still found to be active. The adsorption of T reesei cellulases produced an increase in staining levels after dyeing with an acid dye, but washing fastness was poor. Washing with soap under alkaline conditions removed proteins almost completely. Adsorption of T reesei cellulases is reversible and desorption increases from pH 5 to pH 10. Because of the protein desorption under usual alkaline washing conditions, no practical application of adsorbed cellulases for further finishing processes is suggested and more work is required.     

Nichtionogene Tenside für Spezialwaschmittel

Nonionic Surfactants for Special Washing Agents The use of fatty alcoholethoxylates and alkylphenolethoxylates as surfactants for washing agents has considerably increased during the past years. These surfactants show, especially on synthetic fabrics, a superior washing action compared to anion-active surfactants. Owing to superior biodegradability, the ethoxylated primary and secondary alcohols are used in washing and cleansing agents in preference to poorly biodegradable ethoxylated alkylphenols which, in the future, are likely to lose their significance as surfactants for washing agents. At present an extensive use of nonionic surfactants in amounts comparable to anionic surfactants is limited by the relatively high price of the former and the difficulties involved in their processing.     

Untersuchungen über die toxikologischen Eigenschaften von Waschmittelenzymen

Investigations on the Toxicological Properties of Enzymes Used in Washing Agents Enzymes used in washing agents and enzyme-containing washing agents were tested in animal experiments for their general and local tolerance. The results of these investigations confirm that enzymes employed in washing agents are not toxic. The amounts of enzymes that are added to washing agents do not alter the local tolerance of such products. Similar observations were made in dermatological investigations on testpersons. From the results, it may be concluded that enzyme-containing washing agents do not present any hazard to the health of consumers. The same is also true for allergic reactions. Enzymes used in washing agents do have histamine-and kinin-liberating properties, however, only at such concentration-ranges that are insignificant for the practice.     

Untersuchungen zur Übertragung von Bakterien mittels Seifenstücken bei mehrmaligen Waschvorgängen

Investigations on the Spread of Bacteria through Soap Pieces Due to Repeated Use in Washing Taking a model example which is similar to the usual practice, it was examined as to how far the bacteria can be carried over from one person to the other through the soap pieces. Independent of the nature of soap employed, a thorough washing leads to a reduction of contaminating germs to an extent of nearly 100%. If the piece of soap contaminated with bacteria is used by another person, neither are germs carried over to the hands of this person nor do the bacteria adhere to the soap after the second washing, provided the washing is carried out thoroughly. If a contaminated soap is left as such, a reduction in the number of contaminating germs occur. This is observed especially in the case of deodorant soaps.     

Designing sustainable alternatives for batch operations using an intelligent simulation–optimization framework

The drive towards sustainability has compelled the batch process industries to implement the concept of environmentally friendly plants. However, the temporal nature of processing in these processes obviates the application of traditional waste minimization, material recycling, or energy integration schemes. Further, most of the existing methodologies for generating sustainable alternatives are restricted to specific problems, such as reaction byproduct, wastewater, or solvent minimization. In this paper, we propose an intelligent simulation–optimization framework for identifying comprehensive sustainable alternatives for batch processes. We differentiate between wastes generated by the reaction–separation process and cleaning wastes. A P-graph-based approach is used for identifying the root cause of process waste generation and generating broad design alternatives. Specific variable-level design solutions are then identified and evaluated using process simulation. The cleaning wastes resulting from the optimized process are also minimized using a source-sink allocation method that allows design of recycle network structure. A multi-objective stochastic optimization method is used to integrate the analysis so that the overall process economic and environmental footprint is optimized. We illustrate the proposed methodology using a well-known literature case study involving reaction, distillation and washing operation.     

膨润土K—JT在活性染料净洗工艺中的应用

通过分析膨润土K—JT在净洗工艺中的用量、净洗温度、净洗时间等因素对活性染料染色净洗后的K／S值、水洗牢度的影响,确定膨润土K—JT作活性染料染色净洗剂的最佳工艺条件为：用量3．0g／L,温度95℃,时间为16分钟。自制膨润土K—JT和常规净洗剂净洗后的织物水洗牢度几乎相同,但经自制膨润土K—JT净洗后,净洗残液的CODCr值下降幅度很大。因此,膨润土K—JT是一种很有实用价值的纯棉织物活性染料染色净洗剂。     

Weichspülmittel

Soft Washing Agents The degree of softening achieved at the surface of terry cloth by the action of a washing agent depends upon the structure of the fabric and its molecular weight as well as upon the hardness of water. This is owing to the adsorption of the washing agent on the fibre. Highest degree of softening is attained if at the last stage of washing a cation-active surfactant is added to the rinsing water. However, a quaternary ammonium compound which is employed currently, makes the fabric rather strongly water repelling. It was found out that certain sulfonium compounds impart considerable softness to the fabric without rendering them excessively water repellent.     

Beeinflussung der Waschintensität (WI) in Abhängigkeit von Chemie und Mechanik

Influence of Chemical and Mechanical Factors on the Intensity of Washing Mutual effects of the two significant chemical and mechanical factors that influence the removal of dirt could be studied by treating the fabric in specific manner using a roller-type washing machine, which was developed in author's institute, and a device for measuring the working force. The tests revealed distinctly that intensity of washing is preferably promoted under the action of a solution of washing agent when fibres within the thread are displaced as widely as possible. When the aforesaid conditions are fulfilled, dirt substances from fabrics are suitably dispersed and suspended, which result in optimum washing action.     

Die moderne Parfümierung neuzeitlicher Waschmittel

Modern Perfuming of Present Day Washing Agents In the introduction, changes in direction of odour in perfuming of washing powders is dealt with. Further discussions are devoted to requirements that have to be fulfilled in the development of pleasent and stable perfume oils for their application in washing powders and enzyme-containing washing agents. In this connection, fixation of the odour in powder and in fabric that is washed presents a special problem.     

Möglichkeiten zur Reduktion von Schüttgewichtsabweichungen vom Sollwert bei der Herstellung sprühgetrockneter Waschmittel

Possibilities for Reducing the Deviation from Nominal Value of Bulk Weight in the Production of Spray-Dried Washing Agents In the production of spray-dried washing agents the desired product should contain large amount of beads which ensures easy wettability and dissolution. One drawback of the process is a strong deviation of the bulk weight of the final product from the nominal value. This leads to an overfilling of packages in the subsequent packaging operation which is on the volume basis. A new slurry/air-dispersion process described in this paper increases the economy of spray-drying by a strong reduction in the deviation of bulk weight.