William N. Rowlands

Electroacoustic determination of size and zeta potential of casein micelles in skim milk

Measurements of the zeta potential and particle size of casein micelles in skim milk suspensions at natural and lower pH have been made using the technique of electroacoustics. This technique requires no dilution or change of environment of the casein micelles. The zeta potential obtained at natural pH for a commercial skim milk suspension was -18 mV; it became less negative with decreasing pH. The median particle size observed at natural pH for a commercial skim milk suspension was 0.2 μm, in good agreement with previously reported values. The particle size increased as the pH was decreased.

The biorefinery - challenges, opportunities, and an Australian perspective

Biomass provides the only sustainable source of organic carbon for the production of chemicals used in manufacturing and as liquid transportation fuels. In this article, the authors examine some of the challenges that society faces in the transition from a global economy in which transportation fuels are derived from fossil fuels to one in which they are derived from renewable biomass via a “biorefinery.” In so doing, the authors present an overview of the technology currently available to society and highlight some of the key issues that must be resolved in order to grasp the opportunities that stem from the transition. They conclude by considering the situation of their own country, Australia, to illustrate that the solutions to the challenges will likely depend not only on technology development but also on social, political, and geographical factors.

Production of High Quality Syncrude from Lignocellulosic Biomass

Wood chips were hydrothermally treated in near critical point water in the presence of a catalyst to yield a raw biocrude, containing a wide range of organic components. This product was subsequently distilled to remove its heaviest fraction, which tends to yield chary products if heated above 350 °C. The biocrude obtained has an oxygen content of 12 wt % and was subsequently hydrotreated to obtain a hydrocarbon stream. Varying the hydrotreatment operating conditions and catalyst yielded a deoxygenated syncrude which quality improved with operation severity. The hydroprocessed stream produced under very mild conditions can be further upgraded in conventional refinery operations while the stream produced after more severe hydrotreatment can be mixed with conventional diesel. This proof of concept was demonstrated with commercial hydrotreating catalysts, operating between 350 and 380 °C, 40 to 120 bar pressure and 0.5 to 1 h−1 contact time.