Citric acid solution

SO2 absorbed with buffered citric acid solution. SO2 reduced with H2S to S. H2S produced on site by reduction of S with steam and methane. 

SO2 absorbed with buffered citric acid solution. SO2 stripped from solution with steam. 

Table 3. pH and Specific Gravity of Aqueous Citric Acid Solutions... 

The citric acid solution is deionised at this stage to remove trace amounts of residual calcium, iron, other cationic impurities, and to improve crystallisation. In some processes, trace-impurity removal and decolorization are accompHshed with the aid of adsorptive carbon. 

Citric acid is also commercially available as a 50% w/w solution made either by dissolving crystalline citric acid in water, or a combination or crystalline citric acid, and one of the citric acid process streams. There are several grades of citric acid solutions available, each made according to quaUty which is measured by color and trace impurities. The citric acid content of each grade can be identical, 50% w/w, which is near the solubiUty limit. 

Recommended materials of constmction for pipes, tanks, and pumps handling citric acid solutions are 316 stainless steel, fiber glass-reinforced-polyester, polyethylene, polypropylene, and poly(vinyl chloride). At elevated temperatures, 304 stainless steel is not recommended (Table 8). 

Tests have shown that citric acid is not corrosive to skin but is a skin and ocular irritant (50). Eor these reasons it is recommended that individuals use appropriate personal protection to cover the hands, skin, eyes, nose, and mouth when in direct contact with citric acid solutions or powders. 

Reverse Osmosis Membrane Cleaning. Citric acid solutions are used to remove iron, calcium, and other cations that foul ceUulose acetate and other membranes in reverse osmosis and electro dialysis systems. Citric acid solutions can solubilize and remove these cations without damaging the membranes (94—96). 

High pressure sprays of heated neutralized citric acid solutions replace sandblasting techniques to clean stainless steel equipment and areas not easily... 

The corrosion of tin by nitric acid and its inhibition by n-alkylamines has been reportedThe action of perchloric acid on tin has been studied " and sulphuric acid corrosion inhibition by aniline, pyridine and their derivatives as well as sulphones, sulphoxides and sulphides described. Attack of tin by oxalic, citric and tartaric acids was found to be under the anodic control of the Sn salts in solution in oxygen free conditions . In a study of tin contaminated by up to 1200 ppm Sb, it was demonstrated that the modified surface chemistry catalysed the hydrogen evolution reaction in deaerated citric acid solution. 

Ammonium peroxometalates, (NH4)3NbOg and (NH4)3TaOg, can also be recrystallized, but Belov et al. [512] noted that the process must be performed using citric acid solutions, which are stable at pH = 4-5 up to 100°C. 

Procedure. Dissolve 0.0393 g of pure copper(II) sulphate pentahydrate in 1 L of water in a graduated flask. Pipette 10.0 mL of this solution (containing about 100 jug Cu) into a beaker, add 5.0 mL of 25 per cent aqueous citric acid solution, render slightly alkaline with dilute ammonia solution and boil off the excess of ammonia alternatively, adjust to pH 8.5 using a pH meter. Add 15.0mL of 4 per cent EDTA solution and cool to room temperature. Transfer to a separatory funnel, add lOmL of 0.2 per cent aqueous sodium diethyldithiocarbamate solution, and shake for 45 seconds. A yellow-brown colour develops in the solution. Pipette 20 mL of butyl acetate (ethanoate) into the funnel and shake for 30 seconds. The organic layer acquires a yellow colour. Cool, shake for 15 seconds and allow the phases to separate. Remove the lower aqueous... 

Figure 5.20 The effect of a citric acid solution on tooth structure (a) enamel surface before application, (b) enamel surface after application showing etching, (c) dentine surface before application, (d) dentine surface after application showing the opening-up of the dental tubules (Powis et al, 1982).

Krzek et al. [35] reported the qualitative identification and quantitative analysis of the mixtures of OTC, tiamulin, lincomycin, and spectinomycin in the veterinary preparations by using TLC/densitometry. As stationary phase, they used precoated TLC aluminum sheets, and the mobile phases were mixtures of 10% citric acid solution, hexane, ethanol (80 1 1, v/v), and n-butanol, ethanol, chloroform, 25% ammonia (4 5 2 5, v/v). The other application of TLC or HPTLC for analyzing OTC in the various samples is summarized in Table 2 [36]. 

Procedure Dissolve the specified quantity of the substance being examined in 40 ml DW, and transfer to a Nessler cylinder. Add to it 2 ml iron-free citric acid solution and 0.1 ml thioglycollic acid, mix, make alkaline with iron-free ammonia solution, dilute to 50 ml with DW and allow to stand for 5 minutes. Any colour produced is not more intense than the standard colour. 

Laguerie, C., Aubry, M., and Couderc, J.P. Some physicochemical data on monohydrate citric acid solutions in water solubility, density, viscosity, diffusivity, pH of standard solution, and refractive index, / Chem. Eng. Data, 21(l) 85-87,1976. 

Place the slides requiring microwave irradiation in plastic slide holders in the citric acid solution. 

Citric acid solution, 0.1 M - dissolve 19.212 g citric acid (CgHg07) in water, and make up to 1 I. 

Reaction buffer 40 ml citric acid solution and 8 ml phosphate buffer are mixed and the pH is adjusted to 3.5 using one of either solution (only few additional drops required). 

Citric acid solution 4.203 g citric acid is dissolved in 100 ml demineralized water. 

Phosphate/citrate-buffer 50 ml citric acid solution is put into a 100 ml flask and the pH is adjusted to 4.7 with phosphate solution. The flask is filled up to the 100-ml mark with demineralized water. Store at -20°C. 

Sensory Analysis. A paired comparison test was run to determine if the difference in oil droplet size in the emulsion changed the perceived intensity of the orange flavor. The coarsest emulsion (3.87 pM) and the Microfluidized sample (0.90 pM) from the third set of spray dried samples were compared. The solutions were prepared using 200 ppm flavor in a 10% (w/v) sucrose solution with 0.30% of a 50% citric acid solution added. The amount of each powder required to attain 200 ppm orange oil was calculated on the basis of percent oil in each powder (determined by Clevenger analysis). A pair of samples at approximately 10 C was given to each of 24 untrained panelists. The samples were coded with random numbers. Half the panelists were asked to taste the coarsest sample first while while the other half tasted the Microfluidized sample first. This was done to determine whether or not adaptation was a factor. The panelists were asked to indicate which sample had the most intense orange flavor. 

Citric acid solution- Dissolve 2 42 g of anhydrous citric acid in 250 mL of distilled water... 

Slowly add 250 mL of citric acid solution to the gold solution. Leave to stir for 20-30 min. The color of the solution should develop into red (see Note 6). 

The slow, dropwise addition of the stannous chloride is also important in establishing a stable stain. The Tween-20 and citric acid solutions can be added at a slow pour. Constant stirring is mandatory. 

Calcium Citrate. CaitCoHsCLh 4FLO. white solid, solubility at 18 C 0.085 g/100 g FLO, formed by reaction of calcium carbonate or hydroxide and citric acid solution. 

Figure A1.4.1 Concentration dependence of refractive indices of sucrose, ethanol, and citric acid solutions at 20°C. Data based on tables in Handbookof Chemistry and Physics, 61st Edition (Weast, 1980).

The quantitative analysis of Chincona bark by the classical methods of titrimetry, gravimetry, and polarimetry has been performed for many years in order to ascertain its commercial value. These compounds have been analyzed by GC, GC-MS, TLC, and mainly HPLC (353-361) with UV or electrochemical detection. Ion-pair HPLC was also used with UV or fluorescence detection by Jeuring et al. (357). Photoreactions of Qn in aqueous citric acid solution have been studied by Laurie et al. (358). After isolation of the components by HPLC and TLC, different spectroscopic techniques (MS, NMR, IR) were used to identify the photoproducts. 

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