Grantee Research Project Results

2007 Progress Report: Nanotechnology: A Novel Approach to Prevent Biocide Leaching

EPA Grant Number: GR832371
Title: Nanotechnology: A Novel Approach to Prevent Biocide Leaching
Investigators: Heiden, Patricia , Dawson-Andoh, Benjamin , Matuana, Laurent
Institution: Michigan Technological University , West Virginia University , Michigan State University
Current Institution: Michigan Technological University , Michigan State University , West Virginia University
EPA Project Officer: Hahn, Intaek
Project Period: July 1, 2008 through August 30, 2009
Project Period Covered by this Report: July 1, 2006 through June 30,2007
Project Amount: $333,130
RFA: Greater Research Opportunities: Research in Nanoscale Science Engineering and Technology (2004) RFA Text | Recipients Lists
Research Category: Nanotechnology , Safer Chemicals

Objective:

This project is testing the hypothesis that biocides can be introduced into solid wood contained within controlled release nanoparticles to reduce the leaching of those biocides into the environment while still effectively protecting the wood from biological attack. This would reduce the negative environmental impact of treated wood while increasing its longevity. The approach being tested is the use of core-shell nanoparticles where the function of the shell is to stabilize the nanoparticles in aqueous media so water can carry the nanoparticles into the wood, while the core functions both as a controlled release device, intended to release the biocide at a rate sufficient to maintain effective levels of biocide within the wood, and simultaneously protect the unreleased biocide in the interior of the particle.

Approach:

A new nanoparticle preparation method is being developed to prepare hydrophobic nanoparticles that serve as a biocide reservoir and will moderate the biocide release rate. The nanoparticles will be stabilized in water so that they may be delivered into wood using a conventional modified full pressure-treatment method. American Society for Testing and Materials (ASTM) and American Wood Preservers’ Association (AWPA)-approved methods respectively will be used to determine the biological efficacy of treated sapwood of pine and birch against the brown rot fungus Gloeophyllum trabeum and the white rot fungus Trametes versicolor and the leach rates of biocide from the nanoparticle-treated wood. Wood controls will be prepared by treatment with the same amount of biocide introduced by conventional solution or emulsion methods and evaluated in the same tests in side-by-side studies. All results will be compared and assessed for statistically significant differences.

Progress Summary:

Accomplishments over the last year included studies of effects of reaction variables on nanoparticle size, composition, and morphology on nanoparticles comprised of gelatin grafted with methyl methacrylate (MMA). The results show the grafting of MMA to gelatin to be moderately efficient at 8.6–38.1% with unreacted MMA monomer ranging from 10.9% to 32.5% (conversions depending on formulation). Studies of nanoparticle morphology indicated that the nanoparticles themselves, which ranged in diameter from approximately sixty to several hundred nanometers, were not pure core-shell structures, but appeared to be aggregates of much smaller core-shell nanoparticles of approximately ten to twenty nanometers. The actual delivery of tebuconazole into the nanoparticles and into the wood was determined, along with leaching of tebuconazole from treated wood and the preservative effect of treated wood. The results illustrate two negative effects of using gelatin as a choice for the hydrophilic component of the nanoparticle: it promotes particle aggregation which reduces delivery efficiency of nanoparticles into solid wood and that gelatin serves as an additional food source for fungi and assists in wood decay. Despite the negative effects of gelatin the results after adjusting for actual tebuconazole content in treated wood confirmed the beneficial effect of using controlled-release nanoparticles to reduce leaching and showed similar biological effect in fighting wood decay. Several different types of copper-containing nanoparticles have also been prepared and the effects of reaction variables on particle size, composition, and delivery efficiency are underway. Analytical methods to test for copper content in treated wood are being tested for accuracy and reproducibility and leaching studies are underway for the copper systems.

Expected Results:

This project will demonstrate the environmental benefits of introducing biocide into wood using hydrophobic nanoparticles as a delivery vehicle and controlled release device for organic and inorganic biocides. The primary benefits expected from use of nanoparticles as controlled release devices for biocide in wood are an increased service life of wood and a reduction of biocide loss to leach, which is expected to allow wood to be effectively protected with lesser amounts of biocide than is used now. These benefits are expected to be realized by using a new and more efficient nanoparticle preparation to give a slow biocide release rate coupled with good nanoparticle stability in aqueous suspensions These features will allow the nanoparticles to be delivered efficiently into wood, but once in wood maintain a slow release rate. Successful completion of this project will benefit all ecosystems containing preserved wood. Even greater benefits are expected for wetlands and other moist ecosystems through reduction of biocide contamination, and in forest ecosystems harvested for wood by extending the service life of preserved wood and wood products.

Future Activities:

Over the next year we will continue leaching and biological studies of biocides from wood treated with nanoparticles containing organic and inorganic biocides. We will particularly focus our studies on copper-containing nanoparticles, and evaluate the efficacy of the biocides on the durability of treated wood. We will replicate some of our key results and investigate biobased alternatives to gelatin for the hydrophilic polymer component. A web site will be prepared over the next year for the public to illustrate some of our findings.

Journal Articles:

No journal articles submitted with this report: View all 5 publications for this project

Supplemental Keywords:

water, groundwater, watersheds, soil, leachate, ecological effects, chemicals, toxics, metals, heavy metals, organics, ecosystem, habitat, pollution prevention, green chemistry, clean technologies, innovative technology, waste reduction, waste minimization, environmentally conscious manufacturing, environmental chemistry, conservation, nanotechnology, nanoparticle, controlled-release, biocide reduction, biocide leach, wood preservation, Sustainable Industry/Business, RFA, Scientific Discipline, TREATMENT/CONTROL, INTERNATIONAL COOPERATION, Technology for Sustainable Environment, pollution prevention, Sustainable Environment, Environmental Chemistry, Chemicals Management, Environmental Engineering, Technology, wood preservative, nanomaterials, biotechnology, environmentally benign coating, biocide coatings, nanotechnology, biocide leaching, biocidal nanocomposite coating, alternative materials, clean technologies, cleaner production, alternative building technology, coating processes, green chemistry

Progress and Final Reports:

Original Abstract

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.