Progress 09/01/23 to 08/31/24

Outputs
Target Audience:From a commercial standpoint, our target audience are bio refineries and the engineering firms that work with the refineries. Based on our customer discovery, besides direct refining, the technology is applicable for enhancing the recovery of biofuels from various streams within the biofuel production process. For example, the dewatering distillates will lead to significant energy savings. According to ethanol Producer Magazine's latest data about ethanol production there are 202 ethanol plants in the USA producing 17,468 million gallons per year (Mgpy) of ethanol. These plants are our target audience Our technology can be used in a variety of applications in other biofuel separation which include bio butanol, biodiesel and synthetic biofuels. Jet fuel is a mixture of a large number of different hydrocarbons that are sometimes classified as kerosene or naphtha-type. Generation of aviation biofuel offers many challenges because these are larger molecular weight compounds (compared to ethanol) and are not easily amenable to thermal distillation. We see many emerging opportunities of our technology in the aviation biofuel industry and this industry is a target audience for us. Solvent recovery in waste streams and in solvent recycling are some other important applications of our technology. According to US EPA RCRA public records there are 1049 plants in the USA shipping approximately 10.1M tons/year of dilute solvent waste streams to 139 hazardous waste processing companies. This industry is also a target market and audience for NanoSepex. In general, besides the biofuel and solvent refining industry, we will also reach out to the scientific community at large via publications and presentation at conferences. Our target audience is quite wide and we hope to benefit them in multiple ways. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Summer intership was provided to a Master's Degree student in a STEM major. How have the results been disseminated to communities of interest? Based on discussions with customers and industry partners, it was found that successful field studies with a full scale CNEMMD system is essential for the acceptance of this novel technology by the market. As described above, we have completed construction of a pilot-scale CNEM-MD system with 2 gpm processing capacity. We will use it to demonstrate our technology to potential customers and serve as a key step towards commercialization. Several companies in biofuel production, solvent recycling and aviation biofuel have expressed intention to have us treating their sample feed solutions on the pilot scale system. During this period, we have had discussion with several potential clients for our technology and there appears to be interest from many parties. The prospect of presales appears to be quite good once we complete our pilot testing. We have been working collaboratively with Lawrence Berkley Laboratory and US Navy to use our CNEM-MD to recover isoprenol from low-concentration fermentation solution. Isoprenol is precursor which can be converted to a high-performance jet fuel additive DMCO. Another commercial potential of CNEM-MD technology is in solvent recycling. We have demonstrated the pilot scale CNEM-MD system to Tradebe USA and Veolia, major players in hazardous waste management and recycling. They both expressed great interest to our technology and agreed to run testing on our pilot-scale for recovery of isopropyl alcohol and ethylene glycol. Depending on the results of the pilot testing, they may further fund us to build a full-scale CNME-MD to run at their plant. What do you plan to do during the next reporting period to accomplish the goals?We will be focusing on1. Improve the production yield of the 4" spiral wound CNEM modules. 2.Complete pilot testing on the pilot scale system for enrichment of biofuels in their aqueous solutions and recovery of solvents from low concentration streams.3. Demonstration of the pilot scale CNEM-MD system to potential customers.?

Impacts
What was accomplished under these goals? R&D activities carried out during the reporting period (09/01/2023 - 08/31/2024) and significant results achieved under the specific objectives are described below. 1. Nanofiltration for butanol recovery from high concentration feed Butanol has a water solubility around 73 g/L. CNEM-MD can extract butanol from low-concentration feed and produce permeate with much higher butanol concentration. For example, we demonstrated that CNEM-MD operated at 70°C extracted butanol from feed with 4.17 wt% butanol and produced concentrate with 32.8 wt% butanol. It is desired that butanol in the concentrate can be further enriched. CNEM-MD will not work when the feed butanol concentration is much higher than its water solubility, since the membrane surface will be wetted by the butanol and water penetration will occur. We investigated feasibility of organic nanofiltration (OSN) using CNEM membranes for treatment of aqueous solution containing high butanol concentration. Experimental results showed that butanol was enriched from 30 wt% to 55.8 wt% by nanofiltration at room temperature with our CNEM modules. 2. Characterization of New Hydrophobic PTFE Membrane for CNEM The quality and performance of the base membrane is of key importance to the performance of the CNEM membranes. In the second year of Phase II, we continued our effort to identify alternative membrane suppliers. Hydrophobic PTFE samples of different pore sizes were acquired from a new supplier, characterized and used to make spiral wound modules. The surface quality and mechanical strength of the new membrane is superior to that used before. CNEM membrane fabricated on the new base membrane showed higher water contact angle, indicating higher hydrophobicity than the base membrane which is important in membrane distillation. In the case of ethanol-water mixture, CNEM membrane showed lower contact angle than pristine PTFE membrane, implying higher affinity of CNT layer with ethanol and thus enhanced ethanol transport via CNT pathways. This was also verified by higher ethanol flux achieved by MD using CNEM membrane as compared to MD using unmodified PTFE membrane. 3. Study of Microwave Heating for CNEM-MD Microwaves are commonly utilized as a source of heat in various manufacturing processes, including chemical synthesis and drying, as well as in household kitchens. Recently, microwave-induced membrane distillation (MIMD) has been developed for desalinating water. MIMD can also be used for solvent recovery from aqueous phases since water is microwave active and can be effectively heated using microwaves. Power consumption is an important consideration in MD. As compared to conventional MD, MIMD required less energy, which can be further improved by distributing the microwave radiation uniformly. The combination of direct energy saving and better solvent recovery performance makes MIMD approach quite attractive. We carried out experimental studies to compare solvent separation performance and energy consumption of CNEM-MD using either microwave heating and conventional heating. CNEM-MD with microwave heating showed higher solvent flux and the same solvent selectivity as compared to conventional heating. However, the heating energy consumption of MIMD is significantly lower than that of MD with conventional heating. 4. Development of Large Spiral Wound CNEM-MD Modules with Integrated Air Sparging In the reporting period, we continued to make modifications to the module assembly. End bushings were redesigned to accommodate commercially available central tubes. A guidance ring was designed to guide the sweep air flow toward the permeate channels and prevent the air from flowing through the gap between the membrane element and inner wall of the housing. These modifications were applied for fabrication of large spiral wound CNEM-MD module assemblies used on a 2 gpm pilot scale MD system for pilot testing. 5. System Development at Pilot Plant Scale During the reporting period, we have been working on further development and construction of a skid-mounted pilot-scale MD system. Construction of the pilot-scale MD system was completed. The system has four large spiral wound CNEM-MD module assemblies connected in parallel allowing up to 2 gpm feed flow. The feed flow was heated by an electrical circulation heater. Key process parameters such as feed inlet temperature and pump flow are automatically controlled by process controllers. A 20 channel Data Acquisition Station mounted on the control box can display real-time process parameter data and saves data on a compact flash drive (CF card) for further analysis. Operation of th epilpot scale system and functionality of all its components were validated through commissioning tests on ethylene glycol (EG) enrichment by dewatering from EG-water solutions. 5. Field Demonstration Efforts were made to secure other field demonstration locations. An agreement was reached allowing field demonstration of our 2 gpm pilot scale MD system at integrated research and demonstration facility dedicated to biomass production and processing of one hosting faciliuty. At this point, the hosting facility can only provide an outdoor space for hosting the pilot scale MD system designed for recovery of solvents such as ethanol. In consideration of the weather conditions at the location during the winter, field demonstration was postponed to a later time when the weather is warm enough. We are currently negotiating with another facility to explore the possibility of conducting solvent recovery tests on the pilot scale MD system hosted in an indoor facility during the winter season.

Publications

Progress 09/01/22 to 08/31/23

Outputs
Target Audience:From a commercial standpoint, our target audience are bio refineries and the engineering firms that work with the refineries. Based on our customer discovery, besides direct refining, the technology is applicable for enhancing the recovery of biofuels from various streams within the biofuel production process. For example, the dewatering distillates will lead to significant energy savings. According to ethanol Producer Magazine's latest data about ethanol production there are 202 ethanol plants in the USA producing 17,468 million gallons per year (Mgpy) of ethanol. These plants are our target audience Our technology can be used in a variety of applications in other biofuel separation which include bio butanol, biodiesel and synthetic biofuels.Jet fuelis a mixture of a large number of differenthydrocarbons thatare sometimes classified askeroseneornaphtha-type. Generation of aviation biofuel offers many challenges because these are larger molecular weight compounds (compared to ethanol) and are not easily amenable to thermal distillation. We see many emerging opportunities of our technology in the aviation biofuel industry and this industry is a target audience for us. Solvent recovery in waste streams and in solvent recycling are some other important applications of our technology. According to US EPA RCRA public records there are 1049 plants in the USA shipping approximately 10.1M tons/year of dilute solvent waste streams to 139 hazardous waste processing companies. This industry is also a target market and audience for NanoSepex. In general, besides the biofuel and solvent refining industry, we will also reach out to the scientific community at large via publications and presentation at conferences. Our target audience is quite wide and we hope to benefit them in multiple ways. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Based on discussions with customers and industry partners, it was found that successful field studies with a full scale CNEM-MD system is essential for the acceptance of this novel technology by the market. As described above, we have been actively developing a pilot-scale CNEM-MD system with 2 gpm processing capacity, which will be used to demonstrate our technology to potential customers and serve as a key step towards commercialization. Several companies in biofuel production, solvent recycling and aviation biofuel have expressed intention to have us treating their sample feed solutions on the pilot scale system. In addition to assisting us in design and construction of the pilot scale system, NCERC is also working with us to identify more potential customers in the biofuel production sectors.During this period, we have had discussion with several potential clients for our technology and there appears to be interest from many parties. The prospect of presales appears to be quite good once we complete our pilot testing. We have been working collaboratively with Lawrence Berkley Laboratory and US Navy to use our CNEM-MD to recover isoprenol from low-concentration fermentation solution. Isoprenol is precursor which can be converted to a high-performance jet fuel additive DMCO. Another commercial potential of CNEM-MD technology is in solvent recycling.We have demonstrated our technology and the lab-pilot system to TRADEBE USA, a major player in hazardous waste management and recycling. TRADEBE expressed great interest to our technology and agreed to run testing on our pilot-scale for recovery of isopropyl alcohol and ethylene glycol. Depending on the results of the pilot testing, TRADEBE may further fund us to build a full-scale CNME-MD to run at its plant. What do you plan to do during the next reporting period to accomplish the goals?We will be focusing on the follwoing tasks during the next reporting period: 1. Improve the prodution yield of the 4" spiral wound CNEM modules. 2. Complete construction and test operation of the pilot scale CNEM-MD system. 3. Complete pilot testing on the pilot scale system for enrichment of biofuels in their aqueous solutions and recovery of solvents from low concentration streams. 4. Demonstration of the pilot scale CNEM-MD system to potential customers

Impacts
What was accomplished under these goals? R&D activities were carried out during the reporting period (09/01/2022 - 08/31/2023) and significant results achieved under the specific objectives are described below. 1. Fabrication of Large Area Membranes for Ethanol Separation In our Phase I R&D, we developed the core technology for CNEM membrane fabrication by solution-based coating carried out at ambient conditions. Methodologies was successfully developed for the preparation of stable CNT dispersed in a binding polymer matrix. Polypropylene (PP) support was selected as the base membrane and coated with CNT dispersion to form a CNEM membrane. Our overall goal in this task is to produce large area CNEMs for separation of biofuel including bioethanol. During the reporting period, we further optimized parameters for CNT spray coating and have been able to produce large area CNEM membranes. These CNEM membranes were used to fabricate large spiral wound membrane modules with up to 4² diameter and 0.65 m2 active membrane surface area. We also experimentally studied the influence of number of coated CNT layers on the performance of CNEM membrane for biofuel separation. In brief, stable CNT dispersion with fixed CNT loading was applied onto surface of unmodified hydrophobic PTFE membranes for different times (once, twice and three times) to form CNEM membranes with single CNT layer, double CNT layers or triple CNT layers. Contact angle measurements, TGA analysis and porosity analysis were performed on unmodified PTFE membrane and CNEM membranes with single, double or triple CNT layers. Experimental results showed that CNME membranes, as compared to unmodified PTFE membrane, had higher hydrophobicity as indicated by the increased water contact angle. Increasing the number of CNT coating layers only raised water contact angle slightly. More importantly, in the case of aqueous butanol solution, the lower contact angles of CNEM membranes suggest that immobilized CNTs have stronger interaction with butanol compared to the control membrane, which implies that CNEM membranes can facilitate adsorption and transport of biofuel component in fermentation product. TGA analysis revealed that incorporation of CNTs on the membrane surface enhanced the stability of the membrane. During this reporting period we decided to test butanol to diversify our biofuel portfolio. The behavior of ethanol and butanol are somewhat similar as far as our technology is concerned. Influence of CNT coatings on biofuel (butanol) flux and selectivity was experimentally studied on a bench-scale sweep gas membrane distillation (SGMD) system in our laboratory. In general, the butanol flux increased with the increase in feed temperature for all membranes. All three CNEM membranes showed significantly higher butanol flux and selectivity than the unmodified PTFE membrane. Among CNEM membranes, the one with double CNT layers showed higher flux than those with single or triple CNT layers, although its butanol selectivity is lower compared to the triple layered CNT membrane. Selectivity of butanol is a tradeoff between water flux and butanol flux. In the case of biofuel separation, permeate separation index (PSI) can be used as a performance indicator from its aqueous mixture to achieve a balance between flux and separation factor. PSI can be expressed as PSI= α´J, where α is the separation factor and J is the flux. PSI has the same units as that of the flux since the separation factor is a dimensionless value. The double layered CNT membrane has the highest PSI than the single layered CNT and triple layered CNT membranes. Therefore, CNEM membrane with double CNT layers has been selected for fabrication of large spiral wound CNEM modules for biofuel recovery. 2. Development of Large Spiral Wound CNEM-MD Modules with Integrated Air Sparging In the Phase I project, we developed spiral wound CNEM-MD elements up to 3² in diameter. Commercially available RO membrane housings (plastic material) were modified to host these elements to form CNEM-MD modules. At the early stage of Phase II, we conducted further study to improve the design of the modules, such as optimization of feed and permeate spacer pattern and thickness. The optimized design has been applied to fabrication of larger spiral wound CNEM-MD elements with 4² in diameter. Effective membrane surface area of these larger spiral wound elements is doubled compared to 3² elements. We made modifications to commercially available 4² stainless steel membrane housings to host 4² CNEM-MD elements. Initially, we used the same central tubes (0.65² diameter) for 1.8² and 3² elements for fabrication of 4² CNEM-MD elements. we designed and custom-made two end bushings. Two end bushings were designed and custom-made in order to fit the central tube into the end caps of the stainless steel membrane housing. The 4² CNEM-MD modules will be used in a pilot-scale MD system being developed. Experimental studies were performed to find the optimized module orientation (vertical vs. horizontal) and liquid/air flow directions. Experimental results revealed that, in general, counter-current flows led to higher performance than co-current flows and vertical orientation was superior than horizontal orientation. Butanol is an important chemical with versatile application, such as use as solvent, as precursor for chemical synthesis, as fuel additive, and as a blending component to diesel fuel. Today it is also considered as an alternative biofuel. We conducted preliminary studies to investigate CNEM-MD as a potential candidate for in situ solvent removal during batch and continuous butanol fermentation. Experiments were conducted on the lab-pilot MD system equipped with two CNEM-MD modules connected in parallel. It is apparent that CNEM-MD can effectively extract butanol from low-concentration feed to produce concentrate with several times higher butanol concentration. This can be used to maintain the butanol concentration in fermentation broth to be below the inhibitory level. The results also demonstrated that CNEM-MD can be used for further enrichment of butanol. 3. System Development at Pilot Plant Scale During the reporting period, we have been working on the development of a skid-mounted pilot-scale MD system. With Phase II TABA funding, we signed an agreement with National Corn to Ethanol Research Center (NCERC) to assist us in the design of the system. By far, we have completed the design of a 2 gpm (gallons per minute) pilot-scale MD system, including layout of system components and identification of vendors of all system components. Although the system is currently designed for 2 gpm operation, it can be easily upgraded to have higher processing capacity by replacing some components, such as a larger feed tank, an ECH with higher power rating and a gear pump with higher pumping capacity. Also in the skid design, spaces are reserved for possible installation of more modules and flow controllers in the future. We are currently in negotiation with several contactors regarding construction of the skid-mounted pilot scale system. It is expected the system construction will be completed by the end of 2023. 4. Field Demonstration at Biofuel Production Plant At this point we are looking for fabricators/integrators that can help us to build the pilot unit while we are working in our laboratory to develop the membrane modules that will go into the pilot. Besides testing in our own facility, we are communicating with our industrial partners for securing other field demonstration locations.

Publications