Effluent streams, dyes

Sivakumar and Pandit [13] reported the use of hydrodynamic cavitation for decolorization of dye effluent stream. It has been observed that for same flow area, plate with larger number of small diameter holes gives higher extent of color removal as compared to the plate with smaller number of larger diameter holes. The observed results have been explained on the basis of frequency of turbulence for the two cases. The hydrodynamic cavitation reactor using multiple hole orifice plates has been found to give cavitational yields, which are two times higher than the best acoustic cavitation device (Dual frequency flow cell with capacity of 1.5 L). 

A slug of dye is placed in the feed stream to a stirred reaction vessel operating at steady state. The dye concentration in the effluent stream was monitored as a function of time to generate the data in the table below. Time is measured relative to that at which the dye was injected. 

The presence of color in many industrial effluent streams is highly undesirable. LDHs have been found to be particiflarly effective at removing various synthetic dyes (Table 1) [158]. For example. Acid Blue 29 could be adsorbed on the surface or enter the interlayer region of the LDH by anion exchange an equilibrium time of 1 h with 99 % dye removal was obtained. Furthermore,... 

Some effluent streams, especially those from textile manufacturing facilities using dying processes, can be highly colored even though they are considered to be fairly nontoxic. Due to the stability of modem dyes, conventional... 

Separation of benzene/cyclohexane mixture is investigated most extensively. This is not surprising because separation of this mixture is very important in practical terms. Benzene is used to produce a broad range of valuable chemical products styrene (polystyrene plastics and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline, maleic anhydride (polyester resins), alkylbenzenes and chlorobenzenes, drugs, dyes, plastics, and as a solvent. Cyclohexane is used as a solvent in the plastics industry and in the conversion of the intermediate cyclohexanone, a feedstock for nylon precursors such as adipic acid. E-caprolactam, and hexamethylenediamine. Cyclohexane is produced mainly by catalytic hydrogenation of benzene. The unreacted benzene is present in the reactor s effluent stream and must be removed for pure cyclohexane recovery. 

We assume we keep the flow of the tracer small enough that we do not disturb the existing flow pattern in the reactor. We expect to see a continuous change in the concentration of the effluent stream until, after a long time, it matches the concentration of the feed stream. We are by now experts on solving this type of problem, especially in this simple situation without chemical reaction to complicate matters. Assuming constant density, the differential equation governing the concentration of dye in the reactor follows from Equation 4.38... 

Methylene blue (MeB) is a pollutant present in water stream effluents from dye factories. 

Anionic dyes can be removed from textile effluent streams at acidic pH with chitosan through protonated amine complexation with anionic dye sites. Phenols are common waste products in paper processing. Application of mushroom enzyme tyrosinase to the stream specifically converts phenols into quinones, which can subsequently be absorbed by chitosan. Toxic polychlorinated hiphenols (PCBs), commonly used in plastic processing and lubricants, are a significant source of water contamination. Although the nature of the interaction is not currently known, chitosan treatment shows potential in lowering PCB concentrations. 

Mesitylene is converted to a dye iatermediate, 2,4,6-trimethyl aniline [88-05-1] (mesidine), via nitration to l,3,5-trimethyl-2-nittobenzene [603-71-4] followed by reduction, eg, catalytic hydrogenation (38). Trinitromesitylene has been prepared for use ia high temperature tolerant explosives (39). The use of mesitylene to scavenge contaminant NO from an effluent gas stream has been patented (40). 

In 1980, approximately 111,000 t of synthetic organic dyestuffs were produced in the United States alone. In addition, another 13,000 t were imported. The largest consumer of these dyes is the textile industry accounting for two-thirds of the market (246). Recent estimates indicate 12% of the synthetic textile dyes used yearly are lost to waste streams during dyestuff manufacturing and textile processing operations. Approximately 20% of these losses enter the environment through effluents from wastewater treatment plants (3). 

Recent estimates indicate 29t of the synthetic textile dyes used yearly are lost to waste streams during dyestuff manufacturing and textile processing operations. Approximately 20% of these losses enter the environment through effluents from wastewater treatment plants. 

The method for nitrite determination based on the diazotization-coupling reaction by column preconcentration and on the reduction of nitrate to nitrite using the Cd-Cu reductor column has been proposed for the determination of nitrate and nitrite in water and some fruit samples [6]. On-line monitoring of nitrite in fertilizer process streams, natural and waste water effluents based on the diazotization of nitrite in the sequential injection system with N-(l-naphthyl)etylenediammonium dichloride and the formation of a highly coloured dye has been described [7]. 

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