Reconciling Multi Tube Dye Liquor Ratios across Mixed Capacity Jets
Reconciling liquor ratios across mixed-capacity jets demands adjusting total liquid for static piping dead volume to maintain absolute chemical concentrations.
Electrolyte Equilibrium Shift
Chemical Nature
Chemical phenomenon involving the balance of ions between the aqueous dye liquor and the solid fibre substrate. An electrolyte equilibrium shift occurs when salt is added to the bath to reduce the negative charge on the surface of cellulose fibres. This reduction in the electrical potential barrier allows the dye molecules to move closer to the fibre and begin the exhaustion process.
Reaction Mechanism
Adding sodium chloride or sodium sulfate changes the ionic strength of the solution and forces the dye out of the liquid phase.
Batch Outcome
A gradual increase in salt concentration manages the speed of the electrolyte equilibrium shift to ensure an even distribution of colour. If the change happens too rapidly, the dye clusters on the outermost fibres of the yarn and results in poor penetration or unlevel shades. The final state of the bath depends on the total amount of electrolyte present at the end of the exhaustion phase.
Environmental Impact
High concentrations of minerals in the effluent stream require specialized treatment to prevent damage to local aquatic systems. Managing the electrolyte equilibrium shift with lower amounts of salt is a common goal for mills looking to reduce their ecological footprint. Optimization of the liquor ratio allows for a reduction in the total mass of chemicals needed to achieve the same ionic effect.