Master of Science in Chemical Engineering (MSChE)


Chemical Engineering

Document Type



Cane sugar colorants have been extensively researched but still little is known about their exact compositions. Rather than distinct compounds, they are a mixture of many compounds. Some it is assumed can be classified into the pseudo components that have been defined using gel permeation chromatography, based on molecular weight. The defining of these components has allowed the colorants to be modeled independently, instead of as one lumped color parameter. The measured colored components were modeled using a linear driving force adsorption model, which could be applied in the design process for optimizing the decolorizing capacity of the resins. The majority of these colored compounds possess a charge allowing the removal by packed-bed ion exchangers and decolorizing processes such as the White Sugar Mill (WSM) process. The WSM process has the advantage of producing white sugar directly from sugar cane as opposed to producing raw sugar, which required refining to make white sugar. This is done by performing ultra-filtration on juice, before sending the permeate to a continuous ion exchange operation. One of the disadvantages of the WSM process is the high capital and associated running cost of ultra-filtration. As a result an alternative for this pretreatment has been investigated in the form of a packed carbon bed. Some advantages to a carbon bed pretreatment, followed by the ion exchange treatment, have been identified, namely the removal of colorants and their precursors as well as inorganic material. The removal by ion exchange of these inorganic materials, which can be deposited on the evaporator tubes reducing heat transfer coefficients, could have huge effects on cleaning costs and operability at the mill. It was found that carbon beds could increase the overall color removal, and prolong resin life, even without the removal of suspended solids by ultra-filtration. Preliminary testing was done using hydrogen peroxide as an oxidizing agent in conjunction with a carbon bed pretreatment. Results have shown that this form of treatment could extend the number of bed cycles before regeneration and improve overall colorant removal to the extent that white sugar can be produced directly.



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Committee Chair

Kalliat T. Valsaraj