Phenolic residues

Add dilute sulphuric acid, with stirring, to the cold alkahne solution until the solution is acid to htmus or Congo red paper and the acid, if a solid, commences to separate as a faint permanent precipitate. Now add dilute sodium carbonate solution until the solution is alkahne (litmus paper) and any precipitate has completely redissolved. Extract the clear solution twice with ether evaporate or distil the ether from the ethereal solution on a water bath CAUTION no flames may be near) and identify the residual phenol as under 1. Remove the dissolved ether from the aqueous solution by boiling, acidify with dilute sulphuric acid and identify the organic acid present (see Sections 111,85 and IV, 175). 

Ck)ol the alkaline solution resulting from the distillation of the volatile neutral compounds, make it acid to litmus with dilute sulphuric acid, and add an excess of solid sodium bicarbonate. Extract this bicarbonate solution with two 20 ml. portions of ether remove the ether from the combined ether extracts and identify the residual phenol (or enol). Then acidify the bicarbonate solution cautiously with dilute sulphiu-ic acid if an acidic compound separates, remove it by two extractions with 20 ml. portions of ether if the acidified solution remains clear, distil and collect any water-soluble, volatile acid in the distillate. Characterise the acid as under 2. 

Residual phenol can inhibit Taq polymerase. Hence, a final extraction with chloroform—isoamyl alcohol (49 1) should be performed after phenolization to remove any trace quantities of phenol remaining in the aqueous phase (R3). 

A molecular sieve bed was used to purify continuously the fire-resistant hydraulic fluid (a triaryl phosphate) in a large hydraulic press. Periodically the sieve bed was regenerated by treatment with steam, and then purified air at 205°C. After 9 years of uneventful operation, the bed ignited on admission of hot air. The fuel source was traced to the accumulation of organic residues (phenols or cresols ) on the sieve which were not removed by the steam/air treatment. 

The Phenosolvan process is used in the treatment of wastewaters from plants involving phenol synthesis, coke ovens, coal gasification, low-pressure carbonization, and plastic manufacturing. The residual phenol content after dephenolization is usually in the range 5-20 mg dm and plants treating 500 m water per day are in operation. 

The importance of a correct evaluation of kLa(03) or kla 02) was confirmed in a study on the simulation of (semi-)batch ozonation of phenol (Gurol and Singer, 1983). It was shown that a close match between the measured and the calculated data was only obtained when kLa(02) was measured as a function of the residual phenol concentration. The oxygen mass transfer coefficient was observed to change from kLa(02) = 0.049 s 1 at c(M) = 50 mg IF1 phenol to kLa(02) = 0.021 s- at c(M) = 5.0 mg L 1 phenol. 

For a cleaner preparation, and to remove any residual phenolic substrates, the filtrate can be centrifuged at high speed (20,000 x g) at 4°C for 5 to 20 min. The supernatant is then decanted and tested for DPO activity. The precipitate is washed twice by resuspending in cold 1% KC1 and recentrifuging. Finally, the washed precipitate is resuspended in 1% KC1 or a suitable buffer and is stored at 4°C or deep-frozen. 

After 2 hours of standing at 300 °C the reactive mixture in apparatus 10 is cooled to 100 °C a residual pressure of 13-20 GPa is created to distil the residual phenol. The distillation is carried out until the temperature is 290-300 °C. After that the reactive mixture is cooled to 60 °C and sent to nutsch filter 13 to filter the product, l,3-bis(triphenoxysiloxy)benzene. 

X is the residue of inorganic or organic acid (the fluorine atom, cyanogroup, thiocyan) or acid residue (phenol, mercaptan, etc.). At present hundreds of organophosphorus insecticides are known. Some of them have a very wide action spectrum and kill many species of insects. Organophosphorus insecticides differ by their toxicity for warmblooded animals, stability, period of action, etc. 

Remove residual phenol by five ether extractions and ethanol precipitate (0.1 vol. 3M sodium acetate, 2.5 vol. 95% ethanol)... 

Removal of residual phenol from precleaned effluent by ion exchange (Experiment 117)... 

An array of two electrodes was set up with the first one at a low potential (250 mV) for sample clean up, while the second electrode served for measurements. This array allowed LOD in the ppt range for 5 mL samples of water, after applying an SPE preconcentration step . Simultaneous determination of phenol, 26 substituted phenols and herbicides was carried out by SPE followed by RP-HPLC using a gradient of a solvent modifier and a counter-ion with an array of ELDs. The identity of each chromatographic peak was based on its retention time and the peak height ratio across the electrode array, as compared with those of an authentic standard. The method was applied to determination of phenylurea herbicide residuals, phenol, chlorophenols and nitrophenols in waters of various origins. LOD for the less sensitive analyte, the herbicide Linuron (114), was 0.5 ngL at SNR 3, much lower than the European Community specification . ... 

The activity tests of catalysts for liquid-phase phenol oxidation were carried out at operating conditions for which both heat and mass transfer resistances were negligible. Residual phenol concentration as a function of time for some typical oxidation runs is illustrated in Figure 1. 

Adsorptions conducted so that the residual phenol concentration in the benzene solution was identical with the residual phenol concentration in the aqueous solution. 

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