Trough filters

Filtrates that are acceptable with a low quantity of fines that pass trough the filter cloth in the first few seconds of cake formation. Broadly, and depending on particle size and cloth permeability, the filtrate may contain 1,000 to 5,000 ppm insolubles. 

Ascending, one-dimensional development in a trough chamber with chamber saturatioiL After sample application the HPTLC plate was preconditioned for 30 min in the mobile phase-free trough of a twin-trough chamber (without filter paper lining). 

Jones, R., High-Pass and Band-Pass Digital Filtering with Peak to Trough Measurement Applied to Quantitative Ultraviolet Spectrometry, Analyst 112, November 1987, 1495-1498. 

The majority of commercial LB troughs use the Wilhehny plate method for measurement of surface pressure (II), although some use the alternate Langmuir float method. The plate material most commonly used is cut pieces of filter paper, of negligible cost and completely wetted by water. The other type of plate used is a piece of high-purity platinum metal, which can be cleaned in a flame and gives a reproducible contact angle with water of 60°. 

Chamber saturation is recommended for better reproducibility of the separation — especially if multicomponent mobile phase mixtures are composed of solvents differing in volatility or polarity to a great extent. Moreover, chamber saturation can improve resolution of two components or reduce the formation of secondary fronts. For chamber saturation, the large tank sides are lined with a sheet of filter paper 20 X 20 cm each. Dnring the filling of the mobile phase into the chamber, it is poured onto the filter, which is then completely wetted and soaked by the mobile phase. Note that the wet filter paper is dipped into the mobile phase at the trough bottom. The prepared closed tank will become satnrated within 15 to 30 min depending on the volatihty of the solvent components (withont wetted filter paper it needs more... 

The n-A curves were measured with a trough equipped with a moving blade and a piezoelectric device (Figure 2). Both the trough (286 mm long and 70 mm wide) and blade were coated with Teflon. The subphase temperature was kept within 0.1 °C by use of a water jacket connected with a thermostated circulation system, and the environmental air temperature was kept at 18 °C. The surface tension was measured with a Wilhelmy plate made of filter paper (25 x 25 x 0.25 mm) using a piezoelectric device. The surface pressure(ji) is defined as ... 

A) piezoelectric device, (B) filter paper(Wilhelmy plate), (C) trough, (D) blade, (E) arms,... 

The LB film depositions were performed using a Joyce-Loebl Langmuir Trough IV equipped with a microbalance for measurement of the surface pressure by the Wilhelmy plate method. Filtered deionized water with a pH of 7 was used for the subphase. For the electron beam lithography study, PMMA was spread on the water surface from a dilute benzene solution ( 10 mg PMMA in 20 ml benzene). The novolac/PAC mixtures were spread from solutions ( 20 mg solids in 10 ml solvent) of isopropyl acetate. For the fluorescence studies, the PMMA/PDA mixture was spread on fee water surface from a dilute benzene solution (1.75 mg PDA and 8.33 mg PMMA in 20 ml benzene). Prior to compression, a 20 min interval was allowed for solvent evaporation. The Langmuir film was compressed to the desired transfer pressure at a rate of 50 cm2/min, followed by a 20 minute equilibration period. The Cr-coated silicon wafers and quartz wafers were immersed into fee subphase before... 

Typical procedureA solution of tellurium powder (96 mg, 0.75 mmol) and NaBH (42 mg, 1.12 mmol) in 1.5 mL DMF-terr-butanol (100 1) was heated at 80°C for 30 5 min under argon. After this time the resulting deep purple solution was cooled at room temperature and the substrate (0.5 mmol), pyridine (43 pL, 0.5 mmol) in 2 mL of benzene-DMF (1 3) was added via syringe. The mixture was stirred at room temperature until completion of the starting material (TLC). Then, the reaction flask was opened to air and water was added. After 1 h, the mixture was filtered trough Celite , eluted with EtOAc and washed with brine. Chromatography was allowed to obtain the pure products. 

These filters were used in illmenite beneficiation and titanium dioxide plants. These and their parts like agitators, troughs etc., were lined with a semi-hard flexible ebonite of natural rubber to protect the equipment against the abrasive action of the ore and solid particles in the slurries. 

The other important technique for the study of films at the air/water interface which has recently been introduced is fluorescent microscopy. This technique was introduced by von Tscharner and McConnell [90] and Mohwald [91, 92]. It depends on the fact that certain amphiphilic fluorescent dyes become incorporated into islands of the surface active material under study. Furthermore, where two phases of the surface active material coexist, the dye can often be chosen so that it segregates preferentially into one phase. A shallow Teflon trough is employed with a water immersion objective incorporated into the bottom. The depth of water is adjusted so that the objective focuses on the water surface. The layer of material at the air/water interface is illuminated by a xenon lamp. The fluorescent light so generated passes via the objective and suitable filters to an image-intensified video camera and the image is displayed on a television screen. In some versions of this technique the fluoresence is viewed from above. Most of the pioneering work in this field was devoted to the study of phospholipids, a topic to which we will return. Recently this technique has been applied to the study of pen-tadecanoic acid and this work will be considered here as it relates directly to other papers discussed in this section. 

---