Final Report: Extracting Lignocellulose and Synthesizing Silica Nanoparticles from Rice Husks

EPA Grant Number: SU835084
Title: Extracting Lignocellulose and Synthesizing Silica Nanoparticles from Rice Husks
Investigators: Sun, Luyi , Chen, Haoran , Cheng, Xianbi , DeBord, Katelyn , Fan, Xiaotian , Huang, Wenxi , Long, Kevin , Martin, Jarett , Oliphant, Adam , Wang, Hong , Wang, Weixing , Ying, Xin
Institution: Texas State University , South China University of Technology
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Agriculture , P3 Challenge Area - Materials & Chemicals , P3 Awards , Sustainability


The annual global production of rice husks (RHs) is ca. 160 million tons. The current application of RHs has been very limited, mainly owing to their tough, woody, abrasive nature, low nutritive properties, great bulk, and high ash content. RHs are often burnt in open field in developing countries, generating serious pollution issues, and are disposed at additional cost in developed countries. Therefore, RHs are widely considered as a bio-waste.

RHs are mainly composed of lignocellulose (ca. 85 wt%) and hydrated silica (ca. 15 wt%). We aimed to develop an effective approach to first separate lignocellulose from RHs by dissolving it in ionic liquids (ILs). The dissolved lignocellulose was subsequently separated and can be used as a starting material for fabric products, biofuel, etc. The remaining RH residues after extraction that contain a high concentration of hydrated silica were thermally treated to synthesize nanostructured silica materials, such as nanoparticles, porous frameworks. This project is an interdisciplinary collaboration between students from science major and engineering major. Science students focus on fundamental aspects, while engineering students focus on process design and scale-up. In summary, the objective of this project is to produce two value-added products: lignocellulose and nanostructured silica, from RH biomass, which in turn helps significantly minimize pollutions and cost associated with the current disposal of RHs.

Summary/Accomplishments (Outputs/Outcomes):

We have found that several ILs are effective to dissolve the lignocellulose in RHs. In particularly, 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-ethyl-3-methylimidazolium acetate (EMIMAc) exhibited excellent performance in terms of solubility and IL recyclability. BMIMCl can extract 17.5% lignocellulose from RHs at 150 °C within 6 hours, and 96% BMIMCl can be easily recovered for reuse. EMIMAc can extract 62.2% lignocellulose at 180 °C within 0.25 hour. The recovery rate of EMIMAc is about 90%. The collected lignocellulose can be used for various applications such as paper, fabric products, and biofuel.

We have also managed to synthesize high quality silica nanoparticles and porous frameworks from RHs. Amorphous silica nanoparticles with a narrow size distribution (20-30 nm in diameter) and high surface area of 164 m2/g, and semi-crystalline porous silica frameworks with tunable pore size have been prepared. The silica nanoparticles and porous frameworks can find widespread applications in chemical industry.

We not only clarified fundamental chemistry mechanism of the related reactions, but also developed an effective and efficient engineering process under the collaboration of two groups of students with science and engineering background, respectively.


We have successfully achieved our goal to convert RHs, a biomass whose disposal leads to severe pollution or requires appreciable extra cost for landfill, to two value-added products: lignocellulose and nanostructured silica. The process is properly designed that the key chemicals for lignocellulose extraction, ionic liquids, can be recycled. One PCT/US patent application and one US provisional patent application have been filed to protect our technology. We are now in process to bring our technology to real production.

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other project views: All 8 publications 2 publications in selected types All 2 journal articles
Type Citation Project Document Sources
Journal Article Wang W, Martin JC, Zhang N, Ma C, Han A, Sun L. Harvesting silica nanoparticles from rice husks. Journal of Nanoparticle Research 2011;13(12):6981-6990. SU835084 (Final)
  • Abstract: Springer - Abstract
  • Journal Article Wang W, Martin JC, Fan X, Han A, Luo Z, Sun L. Silica nanoparticles and frameworks from rice husk biomass. ACS Applied Materials & Interfaces 2012;4(2):977-981. SU835084 (Final)
  • Abstract: ACS - Abstract
  • Supplemental Keywords:

    bio-based feed stocks, green chemistry, environmentally benign substitute, biotechnology, waste to value, agricultural byproducts

    P3 Phase II:

    Valuable Chemicals from Rice Husk Biomass