Dyebath monitoring system

Medley and Holdstock developed a mathematical model of the dyeing process, defined as simple depletion theory . Using this theory, they were able to show that an exponential exhaustion profile should give the optimum levelness for the same reasons as Brooks empirical argument - that at the end of the exhanstion phase the risk of nnlevelness is greatest. Their work also involved the development of a commercial dyebath monitoring system in order to apply their theoretical work to a real dyehorrse situation. ... 

The underlying equation that is a common starting point for most dyebath monitoring systems is the Beer-Lambeit (McDonald, 1997) which states that the absorbance of a solution can be given as ... 

A typical dyebath monitoring system such as that shown in Fig. 8.1 enables dyers to monitor multiple dye concentrations in the dyebath while simultaneously measming the temperature, pH and conductivity. Although there are different devices that measure the absorbance of the dyebath and convert these data to concentration or exhaustion, most fall into two main categories direct dyebath monitoring and indirect dyebath monitoring systems. 

In direct dyebath monitoring systems, a small amount of the dyebath circulates through one or more flow cells, where the dyebath absorbance spectrum is measured by a spectrophotometer. The reason for using more than one flow cell is that large variations in the dye concentration will cause absorbances to be measured that are outside the range of the spectrophotometer. Typically, a spectrophotometer operates in a range of 0.005 to 1.5 absorbance units. One of the... 

The other type of monitoring system is the indirect dyebath monitor, where a small sample of the dyebath is sampled and conditioned in a buffer solution to remove any dependency on temperature, salt or pH. Also, if the dye is insoluble in water, it can be dissolved in the buffer solution. Then the dyebath sample is diluted to a range between 0.005 and 1.5 absorbance units before being read by the spectrophotometer. 

CZE separation of synthetic dyes has been approached by simple (borate and citrate) and volatile buffers (ammonium acetate) modified by solvents as well as nonaqueous systems (ammonium acetate/acetic acid in MeOH). Environmental applications of CZE methodologies include the analysis of spent dyebaths and wastewater samples and the monitoring of groundwater migration, where eosin was used as a fluorescent tracer (details in Table 31.8). ... 

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