The Iodine based products in the market are based on strongly basic anion exchange resins. When a device is constructed with these resins, the user is always in the dark and wonders when his device would be exhausted and when he should replenish it. One way the manufacturer recommends is to use the device for a fixed duration of 6 to 12 months and change the contents irrespective, in the process the consumer either runs a risk of over exhausting the device and consumes unsafe water or throws away the unused part of the product and wastes money.
Various efforts to find out indications for exhaust have been made by us. It has been Observed that procedures involving electrical measurement or chemical detection are not suitable. We have also observed that anion exchange resins treated with iodine expand in volume by upto 20 % on use. It has been claimed in some commercial devices that the flow stops once the device is exhausted. This appears to have been achieved with the expanded volume of the resin.
The present invention is based on the observation that the contact disinfectant is continuously removed from the carrier material in form of a thin film. The surface of the iodinated resin particle continues to dissolve till the last traces have gone in solution. These observations are not possible with naked eyes due to original dark colour of the anion exchange resin available in Indian Market.
The operation is practically similar to dressing of a cabbage, which can be dismantled peel by peel finally leaving a small core of the leaves, We use support materials that are either colourless transparent or translucent, Which have been suitably functionalised When the chemical disinfectant such as iodine is deposited on these resins, the colour of the resin turns dark black.
When a particle of such a resin is placed under flow of water, the iodine slowly dissolves in water leaving behind a perfectly clear substrate indication that the disinfectant has completely exhausted. When a large quantity of such a resin is placed in a flow of liquid, the particles that come in contact with the liquid are discolored first, the other part remaining coloured thus giving the indication of the health of the device. |