Performing Department
(N/A)
Non Technical Summary
Fresh fruit, vegetables, and flowers are transported and stored in refrigerated containers. As the produce ripens, ethylene gas is produced, which further ripens the product and can lead to premature spoilage. Most fruits and vegetables emit ethylene gas which promotes ripening. Certain species, such as apples and bananas, produce more ethylene than others. Elevated ethylene levels can significantly reduce storage time; concentrations as high as only 1 ppm can destroy an entire container of produce in one day. The current ethylene removal industry uses single-use potassium permanganate adsorbent blankets or sachets, or a removal device that has a limited lifetime (38 months). Other devices that are on the market or currently being developed include biofilters, ozone generators, and photocatalytic and electrocatalytic devices. Disadvantages of these devices include very strict storage requirements, the potential of contamination by the ethylene-destroying bacteria, the need to employ complex systems to produce ozone, and high manufacturing costs of the photocatalytic device and nanoporous gold electrocatalysts. The goal of this Phase II program is to optimize the adsorbent, complete the design and fabricate a bench top, multi-bed unit. The research will be focused on long-term testing (months instead of days), extended testing under high humidity conditions, testing at concentrations below 1 ppm, testing mold spore kill efficacy of the adsorbent, and evaluation in atmospheres with fluctuating concentrations of ethylene. Engineers at Eltron will be called upon to finalize the design and subsequently build the multi-fixed bed system, which is optimized towards our primary adsorbent and the optimal conditions found during the research. Major benefits of the new system include the ability to regenerate the adsorbent (long lifetimes without having to replace the active species), use of relatively inexpensive materials (no platinum, ruthenium, or gold), and a simple device design, making it inexpensive to manufacture and simple to use. The low maintenance design of the device will allow for increased storage time and reduce spoilage, resulting in reduced costs to all parties along the supply chain - grower, transporter, distributor, and consumer. A renewable ethylene adsorption system would be able to reduce ethylene concentrations within refrigerated dock-side storage containers, refrigerated train cars and grocery store storage refrigerators at minimal long-term cost, and would eliminate the cost and hassle of frequently changing disposable adsorbent beds. By the end of the Phase II program, a prototype low-cost device for the removal of low concentrations of ethylene will have been fabricated, evaluated in a lab setting and in a real-world setting by Ethylene Control Inc., who has already expressed interest in this technology. During Phase II, partnerships for the commercialization of the device will be initiated in order to bring the product to market as soon as possible.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
During Phase I, Eltron developed regenerable adsorbents for ethylene removal and finished preliminary designs of a prototype ethylene removal device. Data collected during the Phase I showed that Eltron's primary adsorbent was capable of removing 100% of the ethylene in a 5 ppm ethylene/air stream for over 24 hours in dry conditions and for 2.5 hours in humid (60% relative humidity) conditions. The adsorbent was shown to be regenerable in both dry and humid conditions through multiple cycles with no substantial loss in activity. The specific objectives for Phase II are as follows: 1) Construct multiple bench-scale reactors, one for short-term/kinetic testing and one for long-term cyclical testing, 2) Scale-up synthesis of downselected adsorbent from Phase I; characterize and test to ensure large scale synthesis does not compromise activity of adsorbent, 3) Perform more in-depth examination of various pelletization and binding techniques and their affect on adsorbent activity in both short- and long-term tests, 4) Test mold spore kill efficacy of regenerable adsorbent, 5) Determine effects of long-term (months) exposure of primary adsorbent to humidified ethylene/air streams, 6) Determine optimal adsorption/regeneration cycle times for adsorbent, 7) Determine the effect gradual ethylene concentration changes have on adsorbent activity over long-term cyclical runs, 8) Use kinetic and long-term data to complete final design of multi-fixed bed, scaled-up reactor system, 9) Fabricate multi-fixed bed reactor system, 10) Run initial tests on scaled-up reactor system to verify effectiveness, and 11) Deliver scaled-up reactor system to Ethylene Control, Inc. or other company involved in refrigeration/transportation of perishables. Major benefits of the new system include the ability to regenerate the adsorbent (long lifetimes without having to replace the active species), use of relatively inexpensive materials (no platinum, ruthenium, or gold), and a simple device design, making it inexpensive to manufacture and simple to use. The low maintenance design of the device will allow for increased storage time and reduce spoilage, resulting in reduced costs to all parties along the supply chain - grower, transporter, distributor, and consumer. A renewable ethylene adsorption system would be able to reduce ethylene concentrations within refrigerated dock-side storage containers, refrigerated train cars and grocery store storage refrigerators at minimal long-term cost, and would eliminate the cost and hassle of frequently changing disposable adsorbent beds. By the end of the Phase II program, a prototype low-cost device for the removal of low concentrations of ethylene will have been fabricated, evaluated in a lab setting and in a real-world setting by Ethylene Control Inc., who has already expressed interest in this technology. During Phase II, partnerships for the commercialization of the device will be initiated in order to bring the product to market as soon as possible.
Project Methods
The approach for this Phase II program will be focused on long-term testing (months instead of days), extended testing under high humidity conditions, testing at concentrations below 1 ppm, testing mold spore kill efficacy of the adsorbent, and testing in atmospheres with fluctuating concentrations of ethylene. Engineers at Eltron will be called upon to finalize the design and subsequently build the multi-fixed bed system, which has been optimized towards our primary adsorbent and the optimal conditions found during the research. During the Phase II program, partnerships for the commercialization of the device will be initiated with the goal of bringing the product to market within five years. Regenerable adsorbents will continue to be prepared using standard methods such as co-precipitation, ion-exchange, and/or impregnation. Physical characterization will be performed on the adsorbents using established analytical techniques including but not limited to: SEM/EDX; XRD; and surface area and pore size analysis. The adsorbents will be evaluated for ethylene removal and regeneration using a pair of custom made fixed bed reactors fitted with humidity sensors and which are capable of operating between -10 oC and 120 oC. One reactor will be used for long-term testing while the other for short term and regeneration cycle optimization studies. All adsorbent testing, including regeneration cycle optimization tests, will be run utilizing low concentrations of ethylene in humidified air during adsorption half-cycles and room temperature or heated air during desorption half-cycles. Gas chromatography will be used to determine removal rates. The long-term reactor will be fitted with an auto-sampling system so inlet and outlet streams can be sampled and evaluated 24 hours a day, seven days a week. All adsorbents will be sent to laboratories specializing in mold spore kill efficacy studies to determine the effectiveness of Eltron's primary sorbent in eliminating this other risk to fresh produce. The effectiveness of the sorbents to handle changes in ethylene concentration over time will also be examined utilizing a pre-reactor cylinder filled with a specified amount of ethylene which is then gradually released and fed to the bed using a constant air flow. Attrition resistance studies will also be performed on optimized adsorbents synthesized with various binders. Kinetic studies will be performed on down selected adsorbent(s) and a prototype, multi-fixed bed reactor system will be designed and built based on this data, tested initially at Eltron and then scaled-up for testing in a real-world environment at a company involved in refrigeration/transportation of perishables.