Progress 09/15/02 to 09/14/07
Outputs
OUTPUTS: Contamination of well water due to pesticides, metals, nitrates, and biological agents represents a serious environmental problem that affects the safety of drinking water in rural areas. Thus, cost-effective means are needed to provide rural residents with affordable ways to meet their water purification needs. Agricultural by-products such as pecan shells are underutilized, plentiful, and renewable feedstocks that can be used to produce activated carbons to meet such needs. This study was conducted to optimize the production of pecan shell-based activated carbons (PSACs) for drinking water purification applications, evaluate and model their adsorption behavior, and test PSACs prototype filters using simulated well water. The production of PSACs was optimized via physical (CO2 and Steam), chemical (KOH, NaHCO3 or H3PO4) or a combination of both (hybrid activation). Chemically activated PSACs were prepared by soaking nutshells in activating agents prior to pyrolysis at
400-700C while in physically activated PSACs shells were directly pyrolyzed at 700C before activation at 700C, 800 C or 900 C. Physicochemical, surface, and adsorption properties of PSACs were evaluated and compared to those of two commercial carbons. Batch and fixed bed column experiments were performed to model PSACs adsorption behaviors. PSACs yield averaged 20% and 34% for physically and chemically activated carbons, respectively. PSACs surface areas ranged from about 400 to 1,100 m2/g, with acid activated carbons exhibiting the highest surface area. The latter also had the highest surface charge, yield, and density. Base activation yielded moderately high surface area (700 m2/g), with surface charges suitable for adsorption of both anionic and cationic species. Overall, PSACs exhibited similar or better adsorption capacity for targeted contaminants than the commercial carbons. Adsorption modeling revealed that adsorption of targeted compounds by PSACs follows the Freundlich
adsorption model, with KOH activated carbons yielding the best model parameters. KOH activated carbons achieved the highest metal removal while CO2 activated carbon achieved the highest nitrate uptake despite its low surface area, highlighting the importance of the right balance between total surface area and surface charge. Testing of PSACs in prototype filter showed that they can successfully compete with existing coal-based carbons to provide reliable and potentially cost-effective means to purify drinking water. Overall, this study demonstrated that pecan shells can be used as precursors for low-cost activated carbons that are custom-designed for water purification applications. This is significant since the development of such low cost water filters from underutilized renewable agricultural waste has the potential to add value to the agricultural sector, alleviate environmental problems caused by the disposal of agricultural by-products, and provide consumers with inexpensive
means to purify their water. The latter could help reduce the incidence of water-borne illness and toxicities, especially in rural areas where residents rely on private water systems for their drinking water needs.
PARTICIPANTS: Faculty Investigators: Dr. Mohamed Ahmedna, African male, served as project PI; Dr. Ipek Goktepe, Caucasian female, served as project co-PI; Dr. Shamsuddin Ilias, Asian male, served as project co-PI; Dr. Kofi Adu-Nyako, African American male, served as project co-PI; Dr. Jimo Ibrahim, African American male, served as project co-PI. Graduate students:Mr. Saydou Niandou, an African American male, Ph.D. in Energy and Environment, and Ms. Mythili Nori an Asian female, MS. Degree in Chemical Engineering, both degrees based on project research.
TARGET AUDIENCES: Students in Agricultural and Food Sciences; Scientific community; Rural residents; Interested private sector
Impacts
This project had a direct positive impact on investigators, students, and the institution and potential benefits for agriculture and food systems. Two of the PIs were new investigators at the time of funding; therefore, this USDA award was critical in enabling their agricultural research career to take roots through hiring of students and research associates, purchase necessary equipment and supplies, participation in professional meetings, and publications. These young scientists were recognized for significant accomplishments in agricultural and food systems research. For instance, the PI (Mohamed Ahmedna) was the recipient of the 2005 USAID George Washington Carver Agricultural Excellence award and the 2007 NC A&T Outstanding Senior Researcher award. The second investigator (Dr. Ipek Goktepe) was also the recipient of the 2005 Gamma Sigma Delta award of Excellence in Research and the 2006 NC A&T Young Investigator award. In addition to PIs, the project provided three
students with unique experiential learning and research experiences in food and agricultural sciences while working toward their graduate degrees (master's and Ph.D.). It also provided participating students multiple professional growth opportunities through paid travel to attend national and local meetings where they expanded their horizon and network. One of the students supported by the project (Mr. Saydou Niandou, a Ph.D. student) won a $10,000 environmental stewardship award from North Carolina Beautiful for his work on project research. At the institutional level, the project enabled the Department of Family and Consumer Sciences to purchase several pieces of equipment (furnace, mills) and leverage project resources to acquire three expensive pieces of equipment (FTIR, autotitration system, and a surface area analyzer) from other funding sources. These instruments were critical to the success of the project and institutional capacity building. Overall, the PIs benefited from
leveraging the capacity building funds to secure over $2 million of funding for related research ideas. The cumulative effect of these outputs resulted in enhanced institutional capacity building, as intended by the USDA, and higher national visibility of the university through presentations by PIs and students at numerous professional meetings. In addition to the institutional capacity building impact (human and infrastructure), research findings from this project have the potential to positively impact the rural economy, the environment, and public health through production of value-added utilization of underutilized agricultural by-products, reduced burden of agricultural waste disposal, and enhanced drinking water quality, respectively. Efforts are under way to test the commercial viability of prototype filters developed out of this project so as to facilitate transfer to interested industry.
Publications
- Ahmedna, M., Nori, M, Yu, J., Ilias, S, and Goktepe, I. 2005. Pecan shell-based activated carbons for drinking purification: carbon production and properties. Paper #18F-25, The 2005 Annual Meeting of the Institute of Food Technologists, New Orleans, LA, July 15-19, 2005.
- Ph.D. Dissertation entitled "Low Cost Nutshell-based Activated Carbons for Drinking Water Purification: Process Optimization and Adsorption Modeling" by Saydou Niandou Mohamed Albachir, December 2007, Specialization Energy and Environment.
- MS. Thesis entitled "Nutshell Based Granular Activated Carbons and Their Use in Drinking Water Purification" by Mythili Nori, May 2005. Specialization: Chemical Engineering.
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Progress 01/01/06 to 12/31/06
Outputs
The processing of pecan yields considerable quantities of shells that have little or no economic value. Pecan shells are high in lignocellulose, and could be an excellent precursor for value-added activated carbons for use in various water purification applications. The objectives of this study were to 1) produce pecan shell-based activated carbons (PSACs) for use in drinking water purification via physicochemical activation methods, 2) evaluate physical, chemical, and surface properties of PSACs, and 3) determine the efficiency of PSACs in removing select organics and metal ions from well water. A total of 20 pecan shell-based carbons were produced using various activation methods. Chemically activated PSACs were prepared by soaking in 50% phosphoric acid or 10-25% of KOH/NaOH/NaHCO3, followed by pyrolysis at 400-700C in inert atmosphere. Physically activated PSACs were produced by pyrolysis at 700C under Nitrogen followed by activation with either steam or CO2 at
700-900C for 1-5 hrs. Physicochemical (yield, attrition, pH, bulk density, and ash), surface (surface area, micropore area, and surface charge) and adsorption (copper, zinc and nitrates uptakes at various levels) properties of the PSACs were compared to those of two commercial carbons specifically designed for water treatment. The best performing carbon within each activation type was selected based on statistical analysis of physicochemical and adsorption properties. Batch and column tests were conducted using the top six best carbons to determine their Freundlich isotherm parameters and derive breakthrough curves, respectively. The top six carbons were produced by phosphoric acid activation at 450C for 1 hr, steam and CO2 activation at 800C for 5 hrs along with potassium hydroxide and sodium bicarbonate activation at 800C for 3 hrs. PSAC yields ranged from 18 to 45%, with steam and phosphoric acid activation showing the lowest and highest yield, respectively. Acid activated carbons
had the highest surface area (>1000 m2/g) and surface charge (1.8 mEqH/g)) followed by base activated carbons with a surface area of 900 m2/g and charge of 0.6 mEqH/g. The highest copper and zinc uptakes were achieved by steam and base activated carbons and the lowest uptakes by the commercial and CO2 activated carbons. The reverse uptake patterns were observed for nitrite. Similar uptakes trends were also observed in breakthrough curves. Carbon uptake patterns were confirmed with Freundlich isotherm parameters with the most efficient and the least efficient carbons in adsorbing the water contaminants exhibiting the largest and smallest k-values, respectively. PSAC ability to remove water contaminants was largely dependent on their surface area, ratio of external surface area to total surface area, and total surface charge. Regardless of the activation method, the best PSACs had higher total surface area, better pore size distribution, and more surface charges than commercial samples.
Therefore, pecan shells have the potential to serve as inexpensive and widely available precursors of value-added activated carbons, with better efficiency in removing water contaminants than commercial reference carbons.
Impacts
About 42 million Americans receive their drinking water from small sources or private wells that are not regulated under the Safe Drinking Water Act. In many instances, wells are shallow and contaminated with pesticides and herbicides and other contaminants such as heavy metals, nitrites and volatile organics. Work performed demonstrated that pecan shell-based carbons capable of efficiently removing organic and inorganic contaminants from water can be custom produced using specific physicochemical methods. Such carbons can be used to develop low cost water filters. Commercial production of water filters from pecan shells and other renewable agricultural waste has the potential to alleviate environmental problems caused by their disposal, add value to the tree-nut industry, and provide consumers with inexpensive means to purify their water. The latter could help reduce the incidence of water-borne illness and toxicities. The multiple benefits of the approach used in
this project could enhance the profitability of the rural economy, and promote the health of rural residents in accordance with the 2006 Science and Education Impact Goals and Topics. These include goals 1 (enhance economic opportunities for agricultural producers) and goal 4 (improve the nation's nutrition and health). The research effort falls under these two goals, while addressing priority topics such as Environmental and natural resource issues (topic 2) and Value-added/new products/rural economy issues (topic 3).
Publications
- Nori M, Ahmedna M, Ilias S, Novak J,Yu J, and Niandou Saydou. 2007. Development and Evaluation of Pecan Shell-based Activated Carbons for Use in Water Purification. Bioresource Technology (In review).
- Niandou, S., Nori, M., Ahmedna, M., Yu, J., Ilias, S., and Goktepe, I. 2006. Production of pecan shell-based activated carbons and their potential use in drinking purification. The 2006 Annual Meeting of the Institute of Food Technologists, Orlando, FL, June 24-28, 2006.
- M. Ahmedna, J. Yu, S. Niandou, M. Nori,, S. Ilias, and I. Goktepe, 2006. Production of Pecan Shell-based Activated Carbons: Process Optimization for Efficient Water Purification. 2006 Annual Meeting of the American Society of Agricultural and Biological Engineers (ASABE), Portland Oregon, July 9-13.
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Progress 01/01/05 to 12/31/05
Outputs
Pecan shell-based activated carbons (PSACs) PSACs were developed using chemical activation (soaking shells in 50% phosphoric acid or 10-25% of KOH, NaOH or NaHCO3) followed by pyrolysis at 400-900 degrees C under N2 or physical activation consisting of pyrolysis under N2 then activation with either steam or CO2. Physicochemical (pH, bulk density, and ash), surface (surface area, micropore area, and surface charge) and adsorption (metals, nitrates and pesticides uptakes) properties of the PSACs were compared to two commercial carbons designed for water treatment. Adsorption isotherms were constructed for each carbon and used as basis for adsorption efficiency comparisons. Carbon yield was 20% and 34% for physically and chemically activated carbons, respectively. Acid activated carbons exhibited higher surface area, bulk density, and lower ash content compared physically activated carbons. The use of base activation led to the development of moderate to high surface
area with surface charges suitable for adsorption of anionic species while acid activation favored cationic adsorption. PSACs had total surface area in the range 400-1,100 m2/g, depending on the pyrolysis and activation methods. PSACs had better pore size distribution, and more available surface charges than commercial carbons. Adsorption data show that PSACs were significantly more effective in removing metals, pesticide/herbicide, and nitrite/nitrate than the commercial references as indicated by adsorption isotherms. This study showed that pecan shells can be used as a source of value-added activated carbons that can be custom designed for efficient removal of well water contaminants.
Impacts
About 42 million Americans receive their drinking water from small sources or private wells that are not regulated under the Safe Drinking Water Act. In many instances, wells are shallow and contaminated with pesticides and herbicides and other contaminants such as heavy metals, nitrites and volatile organics. Low-cost water filtration systems specifically designed for well water will help rural residents purify their drinking water and minimize their exposure to harmful water contaminants. The project could provide rural residents with affordable water purification systems and add value to the nut-tree industry through a novel use of nutshell by-products. This value-added use would also help alleviate the environmental burden of agricultural byproduct disposal. The multiple benefits of the approach used in this project could enhance the profitability of rural economies and promote the health of rural residents in accordance with the 2006 Science and Education Impact
Goals and Topics. The latter include goal 1. enhance economic opportunities for agricultural producers, and goal 4. improve the nation's nutrition and health. This work falls under these two goals while addressing specific priority topics such as environmental and natural resource issues under topic 2, and Value-added/new products/rural economy issues, addressed in topic 3.
Publications
- Seydou Niandou, Mythili Nori, M. Ahmedna, Jianmei Yu, S. Ilias, and I. Goktepe, 2006. Production of Pecan Shell-based Activated Carbons and Their Potential Use in Drinking Purification. 2006 Meeting of the Association of Research Directors (ARD), Atlanta, GA.
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Progress 01/01/04 to 12/30/04
Outputs
Chemically activated pecan shells were prepared by soaking in 50% phosphoric acid followed by pyrolysis at 400-500C under nitrogen. Physically activated pecan shell-based activated carbons (PSACs) were produced by pyrolysis at 700C under nitrogen followed by activation with either steam or CO2 activation at 800-900C. Physicochemical (pH, bulk density, and ash), and surface (total surface area, micropore surface area, micropore volume, and surface charge) and adsorption (metal and pesticides uptakes) properties of PSACs were determined and compared to two commercial references. The results indicated that PSACs yield was about 20 and 34% for physically activated and chemically activated carbons, respectively. Acid activated carbons exhibited higher surface area, bulk density, and lowest ash content compared to steam or CO2 activated carbons and the two commercial reference carbons. Regardless of the activation method, PSACs had higher total surface area than the
commercial references (900 m2/g vs. 700 m2/g), better pore size distribution, and more available surface charges. Adsorption data show that PSACs were significantly more effective in removing metal ions and pesticide/herbicide from well water than the commercial references. Thus pecan shells can be used as precursors of value added activated carbons that are custom designed for efficient removal of typical well water contaminants.
Impacts
About 42 million Americans receive their drinking water from small sources or private wells that are not regulated under the Safe Drinking Water Act. In many instances, wells are shallow and contaminated with pesticides and herbicides and other contaminants such as heavy metals, nitrites and volatile organics. Low-cost water filtration systems specifically designed for well water will help rural residents purify their drinking water and minimize their exposure to harmful water contaminants. The project will provide rural residents with affordable water purification systems and add value to the nut-tree industry through a novel use of nutshells, the industry's main by-products. This dual benefit will enhance the profitability of the rural economy and promote the health of rural residents.
Publications
- M. Ahmedna, Mythili Nori, Jianmei Yu, S. Ilias, and I. Goktepe, 2004. Pecan Shell-based Activated Carbons for Drinking Purification: Carbon production and Properties. Submitted for presentation at the 2005 Annual Meeting of the Institute of Food Technologists, New Orleans, LA, July 21-25.
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Progress 01/01/03 to 12/31/03
Outputs
The research team has purchased and installed necessary equipment and hired most needed personnel. The USDA collaborator and A&T team met twice last year to discuss work plans. Work is ongoing on the pyrolysis and activation of nutshell-based activated carbons using various pyrolysis temperature and activation methods. Pecan shells are the first feedstock used in this project because of their abundance in North Carolina. Nutshells were pyrolyzed at 700 degrees C for 1 hr followed by physical activations with 13%, 30% or 75% CO2 at 800 degrees C for 8 hours. Chemical activation consisted of soaking shells in 50% phospohoric acid and activated at 450 degrees C under a stream of nitrogen. Carbons are being evaluated for physical properties (density, surface area, pore size distribution), chemical properties (pH, surface oxides) and adsorption efficiency for select metals and organics. Data generated will be part of a master's thesis to bepresented at a national meeting
and published in refereed journals.
Impacts
About 42 million Americans receive their drinking water from small sources or private wells that are not regulated under the Safe Drinking Water Act. In many instances, wells are shallow and contaminated with pesticides and herbicides and other contaminants such as heavy metals, nitrites and volatile organics. Low-cost water filtration systems specifically designed for well water will help rural residents purify their drinking water and minimize their exposure to harmful water contaminants. The project will provide rural residents with affordable water purification systems and add value to the nut-tree industry through a novel use of nutshells, the industry's main by-products. This dual benefit will enhance the profitability of the rural economy and promote the health of rural residents.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
This project has just started and therefore, no research work is available for this progress report. The research team is putting in place the necessary structure (personnel and equipment) and finalizing the methodology to carry out the tasks outlined in the proposal. The objectives of the research are to (1) optimize production of nutshell-based GACs for removal of common well water contaminants, (2) evaluate the effectiveness of these GACs in well water purification compared to commercial adsorbents, (3) determine the technical characteristics and projected cost of nutshell-based filters for use in well water treatment, and (4) build and test a prototype nutshell-based well water filtration system equipped with an ozone-based disinfection module.
Impacts
About 42 million Americans receive their drinking water from small sources or private wells that are not regulated under the Safe Drinking Water Act. In many instances, wells are shallow and contaminated with pesticides and herbicides and other contaminants such as heavy metals, nitrites and volatile organics. Low-cost water filtration systems specifically designed for well water will help rural residents purify their drinking water and minimize their exposure to harmful water contaminants. The project will provide rural residents with affordable water purification systems and add value to the tree-nut industry through novel use of nutshells, the industry's main by-products. This dual benefit will enhance the profitability of rural economy and promote the health of rural residents.
Publications
- No publications reported this period
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