Laboratory-scale studies

Usually, the use of hydrogen peroxide in conjunction with ultrasound is beneficial only till an optimum loading [65-67]. The optimum value will be dependent on the nature of the chemical reactions and the operating conditions in terms of power density/operating frequency (these decide the rate of generation of the free radicals) and laboratory scale studies are essential to establish this optimum for the specific application in question. Literature reports may not necessarily give correct solutions (for optimum concentration) even if matching is done with respect to the... 

Large-scale experiments. Integrated processes are basically at the stage of laboratory-scale study in spite of unquestionable progress. Much work in this area is necessary to demonstrate the possibilities on an industrial scale. 

The transfer hydrogenation methods described above are sufficient to carry out laboratory-scale studies, but it is unlikely that a direct scale-up of these processes would result in identical yields and selectivities. This is because the reaction mixtures are biphasic liquid, gas. The gas which is distilled off is acetone from the IPA system, and carbon dioxide from the TEAF system. The rate of gas disengagement is related to the superficial surface area. As the process is scaled-up, or the height of the liquid increases, the ratio of surface area to volume decreases. In order to improve de-gassing, parameters such as stirring rates, reactor design and temperature are important, and these will be discussed along with other factors found important in process scale-up. 

Conkerton EJ, Wan PJ, Richard OA. 1995. Hexane and heptane as extraction solvents for cottonseed A laboratory-scale study. J Am Oil Chem Soc 72 963-965. 

In this article, RPT incidents in various industries are examined. In each case, both laboratory-scale studies and industrial accidents are covered. In the former, usually only simple spills of one liquid upon another were conducted. The effects of a few vmables were tested to determine if they were, or were not, important in achieving an RPT. The results of the small-scale experiments have led to conceptual hypotheses to clarify the initiation of an RPT—and such concepts have, in turn, provided a tentative set of criteria that must be met to achieve an RPT. 

Extensive laboratory-scale studies have been conducted to investigate the triggering mechanism for RPTs when LNG, liquefied petroleum gas (LPG), and liquid refrigerants contact a hot liquid (usually water). These studies are covered in Sections III and VII. The evidence seems overwhelming that RPTs in these cases result from superheating of the cold, volatile liquid to its superheat-limit temperature where prompt homogeneous nucleation occurs in a time period of a few microseconds. (The properties of a superheated liquid and the concept of homogeneous nucleation are reviewed briefly in Section IX.)... 

A common theme developed in this article is that many RPTs can be explained by stipulating that the colder, more volatile liquid is heated, without boiling, to its homogeneous nucleation temperature where prompt vaporization occurs. This sequence then leads to a sharp, but localized, shock. Laboratory-scale studies are concerned primarily with conditions affecting this initial event. Yet there are undoubtedly other mechanisms which could produce similar end results, and some of these alternatives are described. 

A laboratory-scale study of aUcaline and condensate waste streams from a synthetic drug factory at Hyderabad demonstrated that an aerated lagoon is capable of treating the wastewater from this industry [14]. The BOD removal rate K of the system was found to be 0.18/day and 0.155/day based on the soluble and total BOD, respectively. Based on the laboratory studies, a flow sheet (Fig. 2) for the treatment of waste was developed and recommended to the factory. 

Laboratory-scale studies indicate that the aqueous biphasic process is well suited to the recovery of ultrafine, refractory material from soils containing significant amounts of sUt and clay. The main advantages of the aqueous biphasic system in treatment of uranium-contaminated soils are that the process achieves a high removal rate for the uranium contaminant and that such removal is highly selective. Laboratory studies indicate that approximately 99% of the soil is recovered in the clean fraction. 

Aqueous biphasic systems have been used commercially for protein separations, separation of metal ions, ultrafine particles, and organics. Application of the technology for soil decontamination has only been demonstrated in laboratory-scale studies. 

Preliminary estimates for full-scale treatment costs of uranium-contaminated soils were developed based on laboratory-scale studies. The process design uses polyethylene glycol (PEG) (15% solution) and sodium carbonate (10% salt solution) for the aqueous biphasic extractiou system. Uranium is recovered from the salt-rich phase by methanol precipitation. Methanol is then recovered by distillation. 

Based on data from a laboratory-scale study, preliminary costs for capital and operating and maintenance (O M) expenses were estimated for a corona discharge reactor that could treat water containing 4200 parts per billion (ppb) of carbon tetrachloride (with a flow rate of 25 gpm). The liquid corona technology s O M costs were 50% lower than those of the air-stripping/granular activated carbon (GAC) process and were 74% lower than those of the ultraviolet(UV)/oxidation process (D11866L, pp. 1030-1031). 

Reactions in which one reactant is gaseous, the other is in a liquid phase, and the catalyst is dispersed in the liquid phase, constitute a special but not unusual case, for example, the hydrogenation of a liquid alkene catalysed by platinum. A batch reactor is most commonly employed for laboratory scale studies of such reactions. Mass transport from the gaseous to the liquid phase may reduce the rate of such a catalytic reaction unless the contact between the gas and the liquid is excellent (see 1.6). 

Heim and Olejnik [1-3,9] proposed a simple mathematical model based on the theory of statistical moments, whose applicability was confirmed by the results of laboratory-scale studies. 

The above issues associated with prediction of trickle-bed reactor performance has motivated a number of researchers over the past two decades to perform laboratory-scale studies using a particular model-reaction system. These are listed in Table I. Although a more detailed summary is given elsewhere (29), a general conclusion seems to be that both incomplete catalyst wetting and mass transfer limitations are significant factors which affect trickle-bed reactor performance. 

In spite of the potential of this promising technology, development of a practical water treatment system has not yet been successfully achieved. In the last decade, a large number of publications have appeared based on laboratory-scale studies with generally positive results for very diverse categories of toxic compoimds in water. However, technical development to pilot-scale level has not been successfully achieved although there are numerous patents approved worldwide. 

Based on the laboratory-scale study, the degradation of both model waste plastics (3P [150J/PVC [3], 153 kg) and MWP (50 kg) was carried out in a large-scale pilot plant... 

In pharmaceutical development, technology transfer from laboratory scale towards industrialization is generally considered as a critical step. It is therefore necessary to anticipate during laboratory scale studies changes which may occur in drug product quality during scale up. To do so, it is important to identify and control the drug product characteristics (for instance particle size, crystalline form,.. ) which may affect its performances (such as dissolution kinetics, compressibility,...). 

Because of the favorable results obtained in the laboratory scale study, an experiment was conducted to assess the ability to predict the potency of pilot scale rotogranulated beads using data from the experiments performed in the laboratory. The calibration developed for the 55% laboratory scale beads was used to predict the potency of a 30-kg pilot batch. Figure 3 shows a plot of predicted versus actual potency. Prediction error for this study, although acceptable, was slightly higher than in the laboratory study. This error may be attributed to differences in surface characteristics and density between laboratory and pilot scale beads. 

This paper presents results of some laboratory scale studies of the chemical and retorting properties of representative samples from five Australian oil shale deposits. In general terms, the results indicate that these shales differ significantly in their chemical properties both from each other and from the shale of the Green River deposit. 

The authors had already conducted the laboratory scale study and the preliminary pilot plant study, and proposed that "drying-pyrolysis process" (pyrolysis followed by indirect steam drying of dewatered sludge cake) (Fig,-i) could be one of the most economical and feasible alternatives for conventional incineration process. The authors have further conducted the feasibility study on a continuous system of "drying-pyrolysis process to evaluate the performance of the process in pilot scale, and to demonstrate its effectiveness as a thermal processing of sewage sludge. This paper presents the results of this pilot plant study. 

Laboratory-scale studies have shown that 95% of the tetrachloro-ethylene present in soil can be recovered by heating to a temperature range of 90° to 130°C for 4-hr, Additional experiments are necessary to determine whether similar recovery efficiencies can be sustained over deep soil beds. The RF heating techniques have... 

In principle, nevertheless, scaling-up is quite straightforward in vapor permeation and pervaporahon, as happens in other modular processes but care must be taken when using laboratory data for plant design because it is quite common to perform laboratory-scale studies in conditions close to ideal - ophmized feed-flu-id dynamic conditions, extremely low downstream pressure, oversized condensers and extremely low condensation temperature - which are not economic for industrial operation. 

The committee was not aware of any reported results of oxidation of neutralent or rinsates without UV activation. The Army is testing persulfate oxidation of neutralents at the Southwest Research Institute (Table 2-4), but no results were available at the time this report was written. However, the successful oxidation or mineralization of closely related materials, including mustard and nerve agents and their hydrolysates, has been documented. Workers at the U.S. Army Edgewood Research, Development, and Engineering Center (Yang, 1995) have conducted laboratory-scale studies on the reaction of VX, GB, GD (soman), and mustard with hydro-... 

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