Liquid-solid batch extraction

In a series of papers, cinchona alkaloid selectors were in the focus of preparative enantiomer separation methodologies including crystallization [57], countercurrent 

In simple experiments, particulate silica-supported CSPs having various cin-chonan carbamate selectors immobilized to the surface were employed in an enantioselective liquid-solid batch extraction process for the enantioselective enrichment of the weak binding enantiomer of amino acid derivatives in the liquid phase (methanol-0.1M ammonium acetate buffer pH 6) and the stronger binding enantiomer in the solid phase [64]. For example, when a CSP with the 6 -9-(tcrt-butylcarbamoyl)-6 -neopentoxy-cinchonidine selector was employed at an about 10-fold molar excess as related to the DNB-Leu selectand which was dissolved as a racemate in the liquid phase specified earlier, an enantiomeric excess of 89% could be measured in the supernatant after a single extraction step (i.e., a single equilibration step). This corresponds to an enantioselectivity factor of 17.7 (a-value in HPLC amounted to 31.7). Such a batch extraction method could serve as enrichment technique in hybrid processes such as in combination with, for example, crystallization. In the presented study, it was however used for screening of the enantiomer separation power of a series of CSPs. 

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In order to validate the hypothesis mentioned above, the Ni retention capacity of the Lac Tio waste rock was estimated using a batch sorption test performed on a fresh (C1) and weathered (C4) sample, followed by a 3-step Sequential Extraction Procedure (or SEP). The batch sorption test was done using a 10 mg/L Ni solution with an initial pH of 6, an ionic force adjusted to 0.05 M with NaN03 and with a liquid/solid ratio of 25. Some of the batch sorption results are presented in Figure 3. 

The synthesis of 6-hydroxy fluvastatin with M. rammaniana DSM 62752 gave high conversion (>95 %) in shake flask culture on 400 mL scale with 0.1 g L of fluvastatin as well as on 22 L scale in a Wave bioreactor-fed batch process at a final substrate concentration of 0.4 g L Instead of the partial purification by a second solid-phase extraction described above, 6-hydroxy fluvastatin can be obtained in high purity ( 95 %) by, for example, preparative medium-pressure liquid chromatography (MPLC) on RP18 silica gel. ... 

Batch-extraction processes. Perhaps one of the most frequent cases that is encountered is the separation of a neutral organic compound (or compounds) from a solution or suspension (as either a solid or liquid) in an aqueous medium, by shaking with an organic solvent in which the compound is soluble and which is immiscible (or nearly immiscible) with water. 

Classically, batch-mode liquid-solid extractions (LSEs), were used to con-... 

The turn-key multipurpose high pressure pilot unit shown in picture 1 can be used for the continuous extraction of liquid products in a column with structured packings and for the batch extraction of solids in a extraction vessel. It is assembled using the following proven basic modules (see also figure 1) ... 

The synthesis of PET radiopharmaceuticals is always carried out at very small scale (only a few dozen micrograms of the radiopharmaceutical are obtained) and each batch can sometimes only be used for a single patient or a few patients at most. Consequently, there is always a big excess of the precursor in the reaction medium, and proper purification systems must be used to get rid of all the possible contaminants. Such systems must also be very efficient and fast, and the most usual is to apply either semipreparative high-performance liquid chromatography (HPLC) or solid-phase extraction-based procedures. 

This example concerns a discontinuous (batch) liquid-solid extraction process. Here, the quantity of extracted species (y, -< y >- = kgA/kg liq, A = type of species) depends on the following factors the ratio of mixing phases (mi/mg-associated to Zj -< mj/mg >-= kg liq /kg solid), the contact time (t associated to Zj, < T >-= min) the mixing rate (w = Tind -associated to Z3, -< w >-= m/s, n-rotation speed, d - mixer diameter) the mean concentration of one species carrier, which is placed in the liquid phase (Cg -associated to Z4, CgA >-= kg carrier/kg liq) the diameter of the solid particles (d-associated to Z5, d >-= m). The temperature can be another important factor in the process, but initially we can consider that it is constant. Nevertheless, it will be considered as an additional factor in a second step of this analysis. The experiments are carried out with a solid containing 0.08 kg A/kg solid. 

Details of Centrifugal Separators and Use.—No continuously operating separator of the extractor type has been successful. The stumbling block to attaining this end has been the continuous removal of the solids formed but a choice of machine best suited to the work will often increase capacity. If there be not much liquid to be extracted the batch to be placed in the machine may be worked in a removable basket. 

There are several methods available for the extraction of bile salts from serum or plasma. The most convenient methods utilize some form of liquid-solid extraction. An early procedure involved the anion-exchange resin, Amberlyst A-26 (S8), but considerable time and effort was required to perform column chromatography and to concentrate the eluate from the column. The introduction in 1972 of the neutral resin, Amberlite XAD-2, improved the ease of extracting bile acids and their conjugates from serum samples (M6). Further improvement occurred in 1977 with the description of a batch extraction technique using the related neutral resin, Amberlite XAD-7 (B5). With this technique, serum is diluted in 0.1 M sodium hydroxide to release bile acids from albumin and mixed with resin for 1 hour. After washing the resin in dilute alkali, bile acids are eluted with methanol, which cdn be removed on a rotary evaporator (B5). 

Liquid-liquid extraction is a process by which one or more components of a mixture, usually in water, are selectively transferred to another, usually organic liquid. Liquid-solid extraction involves the use of a liquid to selectively remove components from a solid. The majority of laboratory scale extractions are batch extractions, involving separatory funnels. The theory and general techniques are discussed in Chapter 9. 

In the classification scheme in Sec. 1.4.1, the first three entries under liquid-solid separation methods, i.e., ion-exchange, adsoiption, and sorbent extraction, all belong to column separation techniques. While in the batch approach, separations based on these principles may be performed either by static equilibration or by a column technique, online columns are invariably used in FI separations, both for convenience and efficiency. FI column separation systems based on different sorptive mechanisms do not differ strongly in the principles of system design and optimization of operational parameters. Therefore, the principles discussed in the following sections are generally applicable to the different approaches. 

C5. Batch washing will be similar to batch extraction except in continuous addition batch washing tFlgure 13-lD there is no need to pre-saturate the wash liquid with the solid and a filter is used instead of a settler. If the terms are translated the same equations can be used for batch washing. 

In solid-phase extraction (SPE), solutes are extracted from a liquid phase into a solid phase. Most commonly, the liquid phase is a predominately aqueous sample solution and the extractive solid phase consists of small porous particles of silica with a bonded organic outer layer or else it is an organic polymer, such as cross-linked polystyrene. The extraction can take place in a batch mode in which the solid extractant particles are intimately mixed with the sample and then filtered off. However, in chemical analysis it is more common to use a flow-through mode in which the liquid sample is passed through a bed of the solid extractant packed in a small tube. This technique gives more complete extraction of the desired analytes than the batch mode, in which there is only a single equilibration of analytes between the liquid and solid phases. 

Liquid-solid chromatography Liquid-solid chromatography is the technique most widely used to clean up sample extracts. Silica gel, alumina, and Fluorisil are the most commonly used adsorbents. The adsorbent should be free of organic contaminants, inert to the determinands, effective in removing interferences, and uniform in activity from batch to batch. Column chromatography can also be used for preliminary fractionation of sample extracts, e.g., separation of PCBs from organochlorine compounds. 

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