Major Contributions

Despite generations’ effort of scientist and engineers, effective separation of water from crude oil continuous to be a major challenge. By applying basic surface science and materials synthesis to design of a novel interfacially active and magnetically responsive demulsifier with a combination of nano technology with surface science, interfacially active magnetic nano particles were designed to effectively attach these particles to the emulsified water droplets in crude oil. The magnetic properties of the particles allow enhanced coalescence of the water droplets and effective separation of water by an external magnetic field, not only improving the quality of crude oil at reduced capital and operating cost due to shortened separation time, but also reducing the oil loss and associated environmental impact as a result of reduced sludge (waste) volume. More importantly, the magnetic demulsifiers can be regenerated for reuse, reducing again the operating cost.

As noted by Dr. Eric Newell (OC), this handbook is “to provide the technology foundation that will serve as the springboard for the future enhancement required for sustainable development of our vast oil sands resource. It is their bright ideas and innovations that will be so vitally important if we, as Canadians, are to realize the huge socio-economic potential of this strategic global resource.”

Dr. Clem Bowman (FCAE) noted that “Achieving full value from this treasure house will be the task for the next generation of researchers and project developers. But they will be standing on the shoulders of those visionaries who brought the oil sands into full commercial development, as evidenced in the two volumes that comprise this Handbook. Full recognition should be given to the authors of these two volumes for their commitment of time and energy in highlighting this fast moving technological venture, and to their organizations for sharing their experiences.”.

This 438-page report is being used as bench-mark by government and industry to evaluate their programs and to measure their performances. It also provides a scientific and accurate view of oil sands industry. Since its publication, many initiatives have been taken by government and industry to address environmental and sustainability issues facing the oil sands industry. As noted by Senator Elaine McCoy, reprinted in the Ottawa Citizen, “Happily, the Royal Society of Canada Curriculum Vitae: Zhenghe Xu 5 has given us a roadmap outlining precisely what we do know and, more importantly, what we still need to learn. Its expert panel issued their exhaustive review of environmental and health impacts of the oil sands last December.

Their 438-page report is the best I’ve seen on this subject – it deals with the issues clearly, objectively, and without hyperbole, giving us all a much-needed beacon for establishing a research agenda.” The report attracted a high level of media interest, including the front page of the Globe and Mail, an editorial of the National Post, Nature.com, Reuters International, The Economist and the New York Times, just to name a few. It is interesting to note that the report has been quoted in media stories by sources as diverse as the Canadian Association of Petroleum Producers and Green Peace.

After identifying a critical role of effective flocculation of ultrafine particles, a novel organicinorganic hybrid polymer was applied to fluid fine tailings prior to filtration to produce stackable filter cake while recycle the maximum amount of clear (warm) water. By innovative design of process, a flocculation-assisted thickening followed by filtration of sediments (thickener underflow) was proven to be most viable and economical, providing a sustainable solution to challenges of managing tailings, land reclamation, water and energy.

The atomic force microscope (AFM) was used for the first time to measure interaction forces between various components in oil sands in both aqueous and nonaqueous solutions, providing scientific basis for developing cutting edge technology for processing and utilization of natural resources and materials recycling. Combined with ultra-microtome, AFM also allowed us to probe anisotropic properties of clays, providing critical information needed to enhance process performance and tailings handling.

We pioneered study on particle interactions by zeta potential distribution measurement (J77, J81). With this method, we established a detrimental synergistic effect of swelling clays and divalent cations and developed a slime coating theory to explain the depression of bitumen (or coal) recovery and poor froth quality. From this fundamental understanding, we were able to invent a novel process of selective flocculation of solid fines to avoid slime coating, not only improving bitumen (or coal) recovery and froth quality, but also enhancing settling of fine solids in tailings. The determination of fine particle interactions by zeta potential distribution measurement has been extended to a number of other important systems, and adopted by many other research laboratories.

The concept proved in this area had significant impact on how one thinks and designs new flotation machines. The recognition of the work is also illustrated by the invitation for two book Curriculum Vitae: Zhenghe Xu 6 chapter contributions (Flotation Development and Feed Aeration) to Encyclopedia of Separation Science, published by Academic Press. The concept has been adapted by CSIRO (Australia) in to their flotation machine design for fine coal cleaning and implemented in pico bubble flotation technology. Recently, the concept is introduced to oil sands processing with an estimated overall increase in bitumen recovery by up to 2%, accounting for an additional $1,000,000/day net revenue gain, with a significantly reduced impact on environment and greenhouse gas emission. Due to its commercialization and impact to mineral and oil sands industry, this work was highly recognized by invitation to make a plenary presentation at XXIV International Mineral Processing Congress.

Taking advantage of oil spreading characteristics and easy attachment of oil with air bubbles, an (reactive) oily bubble flotation technology was developed and tested to demonstrate significant improvement in valuable (minerals or bitumen) recovery while reducing variability of flotation process dependency on ore characteristics. The paper published (J79) won 2004 best paper award for papers published in Can. J. Chem Eng. and led to an invitation to make a plenary presentation at 6th World Congress of Beneficiation of Phosphate.

With urgent need to reduce mercury emissions in flue gases of coal fired plant while maintain the cost effectiveness of power generation, Dr. Xu’s group applied basic surface science and materials synthesis to design of novel regenerable reactive sorbent. A combination of nano technology with surface science led to the development of silver nanoparticles supported on natural zeolite minerals-magnetite composites. While silver nano particles act as the reactors for amalgamation of mercury, the magnetic properties of the reactive sorbent allowed effective recovery of spent sorbent and regeneration. This type of recycle sorbent is anticipated to become a future generation of technology for abetment of mercury emissions from coal-fired power plant and municipal waste incinerators.

The idea is to replace more expensive activated carbon based sorbent using a waste product of biomass combustion to engineer mercury sorbent using novel chemical and mechanical bromination process. Our patented technology has been demonstrated successful capture of mercury from a plant test, with the potential to be commercialized as replacement of costly activated carbon based sorbent.

Based on fundamental understanding of mercury association with mineral matter in coal, coal cleaning by air dense medium fluidized bed separator as an effective alternative for abetment of mercury emission from coal fired power plants, a major environmental concern. Incorporated with thermal upgrading of coal, this integrated technology will become a corner stone technology for improving air quality by reducing mercury emissions. This work was awarded an outstanding poster award at the 21PstP Annual International Pittsburgh Coal Conference and recently a distinguished paper award at the 33PrdP International Symposium on Combustion. We were Curriculum Vitae: Zhenghe Xu 7 invited to make a plenary presentation on this subject at ChemCon 2006 and at the 6PthP International Symposium on Coal Combustion.

Based on hydrophobic nature of coals, we developed a hydrophobic extraction process using waste oil to recover fine coal lost in tailings ponds, as fuels in the form of coal-in-oil slurry suitable for direct firing in boilers. Our patented technology (P3) has been licensed by Energy Pacific in Idaho, USA.

We developed a process not only to treat acid rock (mine) drainage-an environmental hazardous, but also to produce valuable ferrite of many important uses. This has been widely publicized by news media, including New Scientist (August 10, 1996, p.23), American Chemical Society Press Digest (No. 12050, July 25, 1996), Ground Water Monitor (September 18, 1996, p. 176) and Hazardous Waste News (August 26, p. 272, 1996). The impact of this work is also illustrated by inclusion of the technology in the data base by Industry Canada in Canadian Environmental Solutions.

In this study, we proposed the use of self-assembly with bolaamphiphile molecules to engineer magnetically responsive bio tags for blood cell separation. This work has been recognized internationally as illustrated by an invitation for a keynote presentation at Composites at Lake Louise and for a book chapter contribution to Surfaces of Nanosize Particles and Porous Materials (Marcel Dekker, 1999). The work continued by Dr. S. Gelinas won the best poster award at the Engineering Foundation Conference, Kona, Hawaii, January 1998.

We developed a two-step silica coating theory and technology which allowed extra-thin silica film to protect magnetic nano particles while providing a surface amenable for further modification to tailored applications, such as sorbent for recovery of valuable metals or detoxification of industrial effluent, magnetic demulsifiers, switchable soft gels. This importance of this work is recognized by a high number of more than 300 citations.

This pioneer work laid the foundation for understanding interaction forces between an air bubble and a solid substrate, which is extremely important in flotation widely used in mineral recovery, paper recycling (de-inking), waste water treatment, bitumen recovery and de-oiling of petroleum processing water. The impact of our work is clearly demonstrated by the article having been cited by other researchers for more than 235 times.

By careful design of experiments, the long range hydrophobic attraction which was not considered in the classical DLVO theory, was identified to play a critical role in determining the Curriculum Vitae: Zhenghe Xu 8 stability of a colloidal suspension. A theory was developed to link the additional attractive forces with particle surface hydrophobicity. Incorporating this theory in the classical DLVO theory provides a much more accurate prediction of colloidal suspensions. Built on this foundation, a novel fine coal cleaning process was developed by taking advantage of hydrophobic attractive force to selectively coagulate hydrophobic fine coal, followed by gravity separation of fine coal aggregates.