Praveen Kolar

KI-impregnated oyster shell as a solid catalyst for soybean oil transesterification.

Research on inexpensive and green catalysts is needed for economical production of biodiesel. The goal of the research was to test KI-impregnated calcined oyster shell as a solid catalyst for transesterification of soybean oil. Specific objectives were to characterize KI-impregnated oyster shell, determine the effect of reaction variables and reaction kinetics. The catalyst was synthesized by impregnating KI on calcined oyster shells. X-ray diffraction analysis indicated the presence of portlandite and potassium iodide on the surface and a 31-fold increase in surface as a result of calcination and KI impregnation. Under the conditions tested, ideal reaction variables were 1 mmol g(-1) for catalyst loading, 50 °C for temperature, 10:1 for methanol/oil, and 4h for reaction time. The transesterification followed a first-order reaction (k=0.4385 h(-1)). The option of using oyster shell for the production of transesterification catalysts could have economic benefits to the aquaculture industry in the US.

Heterogeneous catalytic oxidation of lignin into value-added chemicals

Of late there is significant interest in establishing biorefineries for total utilization of lignocellulosic biomass components to produce energy, chemicals and value-added products. Lignin is an abundant and yet underutilized constituent of lignocellulosic biomass that accounts for up to 40% of the energy content. Among several approaches towards value addition of lignin, catalytic oxidation appears to be promising. Hence, the purpose of this report is to provide background information on catalytic oxidation and to update the reader about current research on heterogeneous catalytic oxidation of lignin into value-added products. Additionally, some thoughts are presented to stimulate discussion on lignin oxidation.

Hydrolysis of ozone pretreated energy grasses for optimal fermentable sugar production

Ozonated energy grass varieties were enzymatically hydrolyzed to establish process parameters for maximum fermentable sugar production. Conditions for ozonolysis were selected on the basis of maximum delignification and glucan retention after pretreatment. To study the effect of lignin degradation products generated during ozonolysis on cellulolytic enzymes, hydrolysis was carried out for washed and unwashed pretreated solids. Washing the solids significantly (p<0.05) enhanced glucan conversion from 34.3% to 100% while delivering glucose yields of 146.2-431.9 mg/g biomass. Highest fermentable sugars were produced when grasses were ozonated for maximum delignification and washed solids were hydrolyzed using 0.1g/g Cellic® CTec2. In a comparative study on alkaline pretreatment with 1% NaOH for 60 min, Saccharum arundinaceum exhibited the highest glucan conversion with maximum sugar production of 467.9 mg/g. Although ozonolysis is an effective and environmentally friendly technique for cellulosic sugar production, process optimization is needed to ascertain economic feasibility of the process.

Design and Operation of a Biofilter for Treatment of Swine House Pit Ventilation Exhaust.

A down-flow biofilter was designed to treat exhaust air from a swine barn pit ventilation fan in Raleigh, NC. Computational Fluid Dynamics was used to model airflow to ensure spatial uniformity of treatment. The biofilter medium consisted of ~70% compost and 30% woodchips by volume. The biofilter was evaluated during August 2010 through April 2011 under different summer, fall, and winter conditions. The medium depth was 0.3 m, empty bed residence time (EBRT) was 7.6 s, residence time was 2.7 s, and the biofilter had a unit airflow rate (U) of 0.04 m3/m2-s. A photoacoustic multi-gas field monitor (Innova) was used to measure concentrations of ammonia, carbon dioxide, methane, and nitrous oxide. The Innova was evaluated with regard to its response time for ammonia, nitrous oxide, and methane. Boric acid scrubbers were also used to measure time averaged ammonia concentrations. Air samples were collected and analyzed in a gas chromatograph (GC) for methane and VOCs. Operating conditions such as temperature, medium moisture content, and system pressure drop were measured during biofilter operation. Pressure drop across the fan averaged 125 Pa. The biofilter’s removal efficiencies (RE) for ammonia ranged from 89 to 92%. Greenhouse gases methane and nitrous oxide REs ranged from 13 to 50% and 14 to 17% respectively, while carbon dioxide REs ranged from -6 to 37%. Results show that the biofilter can be effective at removing gases such as ammonia, but also, methane and nitrous oxide. The cost of the system was

Low-temperature catalytic oxidation of aldehyde mixtures using wood fly ash: kinetics, mechanism, and effect of ozone.

1,225 per 0.50 m3/s.

Adsorption of Ammonia on Ozonated Activated Carbon

Poultry rendering emissions contain volatile organic compounds (VOCs) that are nuisance, odorous, and smog and particulate matter precursors. Present treatment options, such as wet scrubbers, do not eliminate a significant fraction of the VOCs emitted including, 2-methylbutanal (2-MB), 3-methylbutanal, and hexanal. This research investigated the low-temperature (25-160 degrees C) catalytic oxidation of 2-MB and hexanal vapors in a differential, plug flow reactor using wood fly ash (WFA) as a catalyst and oxygen and ozone as oxidants. The oxidation rates of 2-MB and hexanal ranged between 3.0 and 3.5 x 10(-9)mol g(-1)s(-1) at 25 degrees C and the activation energies were 2.2 and 1.9 kcal mol(-1), respectively. The catalytic activity of WFA was comparable to other commercially available metal and metal oxide catalysts. We theorize that WFA catalyzed a free radical reaction in which 2-butanone and CO(2) were formed as end products of 2-MB oxidation, while CO(2), pentanal, and butanal were formed as end products of hexanal oxidation. When tested as a binary mixture at 25 and 160 degrees C, no inhibition was observed. Additionally, when ozone was tested as an oxidant at 160 degrees C, 100% removal was achieved within a 2-s reaction time. These results may be used to design catalytic oxidation processes for VOC removal at poultry rendering facilities and potentially replace energy and water intensive air pollution treatment technologies currently in use.

Value-addition of methane via selective catalytic oxidation

In this theoretical research, we investigated ozonated granular activated carbon (OGAC) as an ammonia adsorbent in aqueous systems. Research objectives were to determine the (1) effectiveness of ozone loading on adsorption capacity of activated carbon in aqueous ammonia solutions, (2) kinetics and adsorption isotherms of ammonia adsorption, and (3) effect of volatile organic compounds on adsorption of ammonia from the aqueous phase. Batch experiments indicated that ozonation for 30 min enhanced the adsorption capacity of granular activated carbon from 0.47 ±0.065 mg g-1 to 1.02 ±0.099 mg g-1 due to increased surface oxygen species on activated carbon. These results suggested that activated carbon could be chemically modified to enhance the adsorption of ammonia from aqueous systems. Analysis of the rate data suggested that the adsorption of ammonia on OGAC followed an Elovich model with initial adsorption rate (a) and desorption constants (s) between 0.146 and 1.06 mg g-1 min-1 and 5.5 and 7.75 g mg-1, respectively (25°C to 45°C). The effect of temperature (25°C to 45°C) on adsorption was not found to be significant, suggesting that adsorption on OGAC was non-activated. However, presence of volatile organic compounds (VOCs) such as p-cresol and acetic acid inhibited adsorption of ammonia on OGAC. Future research is needed to synthesize activated carbon that can absorb ammonia and VOCs simultaneously.

Biochemical methane potential (BMP) of Scraped Swine Manure: assessment of anaerobic digestion technology for swine waste management

Selective oxidation of methane into fuels and chemicals has attracted significant attention from researchers worldwide. However, because of its high stability, methane conversion involves multistep reactions. Hence, several catalytic approaches including homogeneous, heterogeneous biological and photocatalytic methods have been explored to selectively oxidize methane into methanol, and other chemicals such as ethane, ethylene and formaldehyde. The purpose of this Review is to discuss the current technologies and catalysts associated with selective oxidation of methane, reaction variables that influence selectivity and conversion, and challenges and available opportunities with methane conversion technologies. In addition, a few ideas to enhance the selectivity and conversion of methane are also presented.

Technical Note: Synthesis of Solid Acid Catalyst from Tobacco Stalk for Esterification of Oleic Acid

Abstract. Concentrated swine farming operations produce sizeable amounts of manure, which is commonly treated using anaerobic lagoons that have been associated with a number of adverse environmental and health problems. The benefits of anaerobic digestion (AD) of manure – methane capture, renewable energy, and pathogen inactivation — have been well documented; however, an important barrier to adoption of this technology for many swine producers is the high water content of manure from water-wash systems that use lagoon treatment lagoons. The recent introduction of a separation system allows for the collection of manure without added water either as separate scraped solids and liquids or as whole slurry. Experimentally determining the reaction rate of methane production of manure solids will help define new opportunities for this technology and will illustrate the potential of utilizing AD for high manure solids. A biochemical methane potential (BMP) assay of feedstock collected with the scraper system was conducted at mesophilic temperature (35°C) to determine methane production potential. Unexpected results included continuous drop of the methane production readings, and negative volume readings for the control replicates, which indicate a negative pressure inside batch reactors. While the research team was unable to explain observed results, possible explanations include inadequate inoculum sourcing, high operating temperature, and incomplete factors consideration for final gas measures. Existing literature does not offer comparable results to the results obtained during the BMP assay. Future research should focus on understanding the various factors that must be considered when conducting a BMP assay, as no official protocol is available. .

Advanced oxidation of toluene using Ni-olivine catalysts: Part 1. Synthesis, characterization, and evaluation of Ni-olivine catalysts for toluene oxidation.

Abstract. The present research evaluated tobacco stalk as raw material for synthesis of a solid acid catalyst for esterification of oleic acid. The objectives were to synthesize and characterize the solid acid catalyst and determine the effect of impregnation and reaction times on esterification of oleic acid. The catalyst was synthesized by carbonizing tobacco stalk at 300°C followed by impregnation of sulfuric acid for up to 6 h. Analysis of the catalyst surface revealed presence of sulfur and significant decrease of acid value from 7.6 ± 0.01 to 2.42 ± 0.02 (P