University of Northern Colorado
Campus Box 98
Greeley, CO 80639
Post-Doc (Food Chemistry and Packaging) – Rutgers University, New Brunswick, NJ
Ph.D. (Chemical Engineering/Chemistry) – New Jersey Institute of Technology, Newark,
M.S. (Chemical Engineering) – Tianjin University, Tianjin (China)
B.S. (Chemistry) – Tianjin University, Tianjin (China)
Research/Areas of Interest
Organic Reactions Catalyzed by Enzymes and DNA-Based Hybrid Catalysts
The fundamental understanding of enzyme behaviors in different solvent systems can
further guide the use of biocatalysis in many organic reactions. We are particularly
interested in understanding the mechanisms of enzyme-catalyzed reactions in non-aqueous
media (such as ionic liquids, deep eutectic solvents, and glymes), as well as the
preparation of new enzyme-compatible solvent systems. In addition, we are interested
in new hybrid catalysts prepared by binding metal complexes with DNA molecules as
chiral scaffold. These hybrid catalysts can be widely used in the asymmetric synthesis
of Michael addition, Diels-Alder reaction and Friedel-Crafts alkylation.
Synthesis of Polyesters and Their Derivatives via Enzymatic Polymerization
Polyesters, such as polylactides (PLAs) and polylactones, are sustainable and biodegradable
polymers with a wide range of applications in packaging, horticultural materials,
and biomedical fields. These polyesters can be prepared by various chemical methods
such as polycondensation and ring-opening polymerization (ROP). Our group is interested
in a more benign approach of using enzymatic ring-opening polymerization (ROP) to
synthesize these polyesters and polyester-grafted nanocellulose materials.
Deep Desulfurization of Liquid Fuels by Oxidative Extraction Using Ionic Liquids
Since 2005, more stringent regulations have been enforced to reduce the sulfur content
for gasoline and diesel oil to 10-30 ppm level. To meet this ultra-low sulfur limit,
the conventional hydrodesulfurization (HDS) method is not always efficient, particularly
in removing aromatic sulfur compounds such as benzothiophene (BT), dibenzothiophene
(DBT), and their alkyl derivatives. Among many alternative deep desulfurization approaches,
oxidative extraction using ionic liquids (ILs) has attracted remarkable attention
due to the favorable properties of ILs such as low volatility, high solubility of
sulfur compounds, high thermal/chemical stability, and tunable physical properties.
Our group plans to synthesize inexpensive task-specific ILs that can efficiently remove
aromatic sulfur compounds from fossil fuels.
Biocatalysis for Cellulosic Ethanol and Biodiesel Preparations
Cellulosic ethanol and biodiesel (fatty acid monoester) represent two important categories
of renewable biofuels. We are interested in developing inexpensive solvent systems
(including ionic liquids) for pretreating cellulosic biomass, and investigating the
enzymatic hydrolysis and fermentation of pretreated lignocelluloses. In addition,
our group is interested in developing inexpensive and novel deep eutectic solvents
as reaction media for the enzymatic preparation of biodiesel from renewable lipid
sources such as microalgae. We are also interested in exploring the chemical preparation
of biodiesel using inexpensive ‘green’ solvents.
(see a full list of publications at Google Scholar or Our Research Group Website)
- Hua Zhao*, Gary A. Baker, and Qi Zhang, Fuel, 189, 334–339 (2017). “Design Rules of Ionic Liquids Tasked for Highly Efficient
Fuel Desulfurization by Mild Oxidative Extraction”.
- Hua Zhao*, Gary A. Baker, Durgesh V. Wagle, Sudhir Ravula, and Qi Zhang, ACS Sustainable Chemistry and Engineering, 4, 4771–4780 (2016). “Tuning Task-Specific Ionic Liquids for the Extractive Desulfurization
of Liquid Fuel”.
- Hua Zhao* and Kai Shen, Biotechnology Progress, 32, 891–898 (2016). “G-Quadruplex DNA-Based Asymmetric Catalysis of Michael Addition:
Effects of Sonication, Ligands, and Co-Solvents”.
- Robert J. Visalli, Hannah Ziobrowski, Kameswara R. Badri, Johnny J. He, Xiugen Zhang,
Sri Ranjini Arumugam, and Hua Zhao*, Bioorganic & Medicinal Chemistry Letters, 25, 3168–3171 (2015). “Ionic Derivatives of Betulinic Acid Exhibit Strong Antiviral
Activity against Herpes Simplex Virus Type-2 (HSV-2), But Not HIV-1 Reverse Transcriptase”.
- S. Xia, G. A. Baker, H. Li, S. Ravula and Hua Zhao*, RSC Advances, 4, 10586-10596 (2014). “Aqueous Ionic Liquids and Deep Eutectic Solvents for Cellulosic
Biomass Pretreatment and Saccharification”.
- Tang, Gary A. Baker and Hua Zhao*, Chemical Society Review, 41, 4030-4066 (2012). “Ether- and alcohol-functionalized task-specific ionic liquids:
Attractive properties and applications”.
- Tang, Gary A. Baker, S. Ravula, John E. Jones and Hua Zhao*, Green Chemistry, 14, 2922-2932 (2012). “Novel PEG-functionalized ionic liquids for cellulose dissolution
- Hua Zhao*, Gary A. Baker and Shaletha Holmes, Organic and Biomolecular Chemistry, 9, 1908-1916 (2011). “New eutectic ionic liquids for lipase activation and enzymatic
production of biodiesel”.
- Hua Zhao*, and Zhiyan Song, Biochemical Engineering Journal, 49, 113-118 (2010). “Migration of reactive trace compounds from Novozym® 435 into organic solvents and ionic liquids”.
- Hua Zhao*, Gary A. Baker, and Janet V. Cowins, Biotechnology Progress, 26, 127-133 (2010). “Fast enzymatic saccharification of switchgrass after pretreatment
with ionic liquid”.
- Hua Zhao*, Zhiyan Song, Olubajo Olubajo, and Janet V. Cowins, Applied Biochemistry and Biotechnology, 162, 13-23 (2010). “New ether-functionalized ionic liquids for lipase-catalyzed
synthesis of biodiesel”.
- Hua Zhao*, Cecil L. Jones, and Janet V. Cowins, Green Chemistry, 11, 1128-1138 (2009). “Lipase dissolution and stabilization in ether-functionalized
- Hua Zhao*, Gary A. Baker, Zhiyan Song, Olarongbe Olubajo, Lavezza Zanders, and Sophia
M. Campbell, Journal of Molecular Catalysis B: Enzymatic, 57: 149-157 (2009). “Effect of ionic liquid properties on lipase stabilization under
- Hua Zhao*, Gary A. Baker, Zhiyan Song, Olarongbe Olubajo, and Vernecia N. Person,
Journal of Biotechnology, 139, 47-54 (2009). “Regenerating cellulose from ionic liquids for an accelerated
- Hua Zhao*, Gary A. Baker, Zhiyan Song, Olarongbe Olubajo, Tanisha Crittle, and Darkeysha
Peters, Green Chemistry, 10, 696-705 (2008). Designing enzyme-compatible ionic liquids that can dissolve
- Hua Zhao*, Journal of Chemical Technology and Biotechnology, 81(6), 877-891 (2006). “Are ionic liquids kosmotropes or chaotropes? — An evaluation
of available thermodynamic parameters for calculating the ion kosmotropicity of ionic
- Hua Zhao*, Sophia M. Campbell, Lee Jackson, Zhiyan Song and Olarongbe Olubajo, Tetrahedron: Asymmetry, 17(3), 377-383 (2006), “Hofmeister series of ionic liquids: kosmotropic effect of
ionic liquids on the enzymatic hydrolysis of enantiomeric phenylalanine methyl ester”.
- Hua Zhao, Journal of Molecular Catalysis B: Enzymatic, 37, 16-25 (2005), “Effect of ions and other compatible solutes on enzyme activity,
and its implication for biocatalysis using ionic liquids”.