Jeremy McLeod

Doctor of Philosophy, (Process Engineering)
Study Completed: 2007
College of Sciences


Thesis Title
Crystallisation of Lactose.

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Mr McLeod focused on the nucleation and growth kinetics of alpha lactose monohydrate. Lactose represents approximately one third of the total solids in bovine milk and is recovered from whey and whey permeates using crystallisation. A model has been produced that can predict the changing concentration profile as lactose crystallises from an industrial solution. The primary nucleation of alpha lactose monohydrate was investigated. The work identified the changing relationship, which occurs with increasing supersaturation, as lactose nucleation moves from being dominated by the heterogeneous mechanism to the homogenous mechanism. The effect of mixing on the primary nucleation rate was studied using a Rushton turbine and a Venturi to agitate the system. Increasing the agitation rate increased the frequency of activated molecular collisions, but the critical nucleus size remained constant. A strong correlation was found, for both mixing systems, between the nucleation rate and the frequency of vortex shedding.

Professor Tony Paterson
Professor John Bronlund
Professor Jim Jones