Poritosh Roy

Effects of surfactant and electrolyte concentrations on bubble formation and stabilization.

As interest in the application of microbubbles grows, it is becoming increasingly important to understand the factors affecting their formation and properties in order to effectively generate microbubbles. This paper investigates the effect of surfactant concentration and electrolyte addition on the size distribution and stability of microbubbles. The anionic surfactant sodium dodecyl sulfate (SDS) was used as the surfactant. Minimum bubble diameter and maximum stability were achieved at surfactant concentrations above the CMC. The effect of the electrolyte addition was studied by adding sodium chloride (NaCl) at an SDS concentration below the critical micelle concentration (CMC). Addition of NaCl decreased bubble size and improved bubble preparation to a certain extent. The addition of salt at low concentrations did not affect the surface tension; however, the surface tension was reduced as salt concentration was increased and reached a constant value for NaCl concentrations above 0.25%. The presence of NaCl resulted in a significant decrease in zeta-potential, implying a reduction in the surface charge of SDS micelles. This result suggests that the presence of NaCl may improve the generation and stability of bubbles by enhancing the structures of the adsorption monolayer and interfacial film.

Life cycle of meats: an opportunity to abate the greenhouse gas emission from meat industry in Japan.

The food industry is one of the worlds largest industrial sectors, hence a large contributor of greenhouse gases (GHG) which cause global warming. This study evaluates the life cycle of various types of meat to determine if the GHG emission from the meat industry in Japan could be reduced if the population makes different dietary choices. It was confirmed that the GHG emission of beef was greater than that of pork or chicken. The GHG emission from meat in general also depends on the per capita caloric intake (if meat supplies the recommended animal protein or contributes to it at the present rate). In a healthy and balanced diet (9.2 MJ i.e., 2200 kcal in total, where either mixed meat or chicken or pork or beef contributes 2.2%), the GHG emission is estimated to be 0.28 or 0.17 or 0.15 or 0.77 kg CO₂ eq/person/day, respectively. A change in consumption patterns (from beef to chicken or pork) and the adoption of a healthy and balanced diet would help to abate about 2.5-54.0 million tons (CO₂ eq) produced by the meat industry each year in Japan.

Processing Conditions, Rice Properties, Health and Environment

Rice is the staple food for nearly two-thirds of the world’s population. Food components and environmental load of rice depends on the rice form that is resulted by different processing conditions. Brown rice (BR), germinated brown rice (GBR) and partially-milled rice (PMR) contains more health beneficial food components compared to the well milled rice (WMR). Although the arsenic concentration in cooked rice depends on the cooking methods, parboiled rice (PBR) seems to be relatively prone to arsenic contamination compared to that of untreated rice, if contaminated water is used for parboiling and cooking. A change in consumption patterns from PBR to untreated rice (non-parboiled), and WMR to PMR or BR may conserve about 43–54 million tons of rice and reduce the risk from arsenic contamination in the arsenic prone area. This study also reveals that a change in rice consumption patterns not only supply more food components but also reduces environmental loads. A switch in production and consumption patterns would improve food security where food grains are scarce, and provide more health beneficial food components, may prevent some diseases and ease the burden on the Earth. However, motivation and awareness of the environment and health, and even a nominal incentive may require for a method switching which may help in building a sustainable society.

Evaluation of the life cycle of bioethanol produced from rice straws.

This study evaluated the life cycle of bioethanol produced by enzymatic hydrolysis of rice straw. Net energy consumption, CO(2) emission and production costs were estimated to determine whether environmentally preferable and economically viable bioethanol can be produced from rice straws. Two varieties of rice straw (Koshihikari and Leafstar), three energy scenarios (F-E-RH: Fuel-Electricity-Residues used for Heat; F-E-RE: Fuel-Electricity-Residues used to generate Electricity; F-RE: Fuel-Residues used to generate Electricity) and three types of primary energy (heavy oil; LNG: liquefied natural gas; agri-residues) were considered. The net energy consumption, CO(2) emission and production costs were estimated to be 10.0-17.6MJ/L, -0.5 to 1.6kg/L and 84.9-144.3¥/L (1 US

Characterization of a soybean oil-based biosurfactant and evaluation of its ability to form microbubbles.

≈100¥), respectively, depending on the feedstock and scenarios of this study. A shift in energy scenarios or in the type of primary energy (heavy oil to LNG or agri-residues) not only reduces emissions and production costs of bioethanol from rice straw, but may also reduce the fluctuation in production cost over time and risk on investment, which would encourage more investment in this sector.

Hot air drying characteristics of sweet potato using moisture sorption isotherm analysis and its quality changes during drying.

This paper characterizes the physico-chemical properties of the soybean oil-based polymeric surfactant, Palozengs R-004 (hereafter referred to as R-004). The surface activity of R-004 is comparable to the reported activities of biosurfactants produced by microorganisms and higher than some of the conventional synthetic surfactants. The surface tension of Milli-Q water was reduced to a minimum value of roughly 30mN/m at a concentration of about 0.07wt.%. R-004 exhibited a unique aggregation behavior: small aggregates (pre-micelles) were formed at very low concentrations. Zeta-potential measurements showed that the micelles of R-004 are negatively charged due to the presence of carboxylic groups. The ability of R-004 to form and stabilize microbubbles was evaluated and was found to be greatly affected by filtration while remaining independent of R-004 concentration over the concentration range studied (0.05-0.5wt.%). These results suggest that a very low level of surfactant can be used to produce microbubbles without affecting their properties. Our results suggest the possibility of using soybean oil-based surfactants to food, pharmaceutical, and cosmetic applications.

Greenhouse gas emissions and production cost of ethanol produced from biosyngas fermentation process

Changes in the quality of sweet potato during hot air drying, such as L-ascorbic acid, sugar content, surface color and hardness, and drying characteristics, were investigated at temperatures of 30, 40, 50, and 60°C. Equilibrium moisture contents (EMC) of sweet potato samples in the desorption process were measured by a static method at the four aforementioned temperatures and six selected relative humidity levels. Using both the measured moisture content data in the drying test and the EMC values, hot air drying characteristics of sweet potato was estimated. Changes in L-ascorbic acid content of sweet potato during hot air drying was measured, wherein a first-order reaction rate equation was applied to model the change in decomposition of L-ascorbic acid content. In addition, surface color, sugar content, and surface hardness were also measured. The total color change (?E) of the samples was observed to decrease as drying temperature was increased. The effects of sample sugar concentration on surface hardening during hot air drying of sweet potato are discussed.

Review of syngas fermentation processes for bioethanol

Life cycle (LC) of ethanol has been evaluated to determine the environmental and economical viability of ethanol that was derived from biosyngas fermentation process (gasification-biosynthesis). Four scenarios [S1: untreated (raw), S2: treated (torrefied); S3: untreated-chemical looping gasification (CLG), S4: treated-CLG] were considered. The simulated biosyngas composition was used in this evaluation process. The GHG emissions and production cost varied from 1.19 to 1.32 kg-CO2 e/L and 0.78 to 0.90

Life cycle assessment of ethanol derived from sawdust.

/L, respectively, which were found to be dependent on the scenarios. The environmental and economical viability was found be improved when untreated feedstock was used instead of treated feedstock. Although the GHG emissions slightly reduced in the case of CLG process, production cost was nominally increased because of the cost incurred by the use of CaO. This study revealed that miscanthus is a promising feedstock for the ethanol industry, even if it is grown on marginal land, which can help abate GHG emissions.

Effects of cultivation, transportation and distribution methods on the life cycle inventory (LCI) of fresh tomato

Bioethanol is recognized as an important renewable and sustainable transportation fuel. Although synthesis gas (syngas: CO, H2, CO2) produced from lignocellulosic biomass (forest or agricultural biomass) is being used in the production of bioethanol by both chemical catalytic and biosynthetic processes, the latter are noted to have more advantages. In the biosynthesis process, such as the fermentation of syngas, bioethanol is produced along with acetate, butanol, butyrate, methane, peptone, and formaldehyde. Although progress has been made on research and development for the utilization of syngas on fermentation technology, the major barriers for the commercialization still include low yield, expensive biological catalyst, slow kinetics, low gas–liquid mass transfer, and challenges with catalytic separation and recycling. This paper presents a review on fermentation product impurities, microorganisms, chemical reactions, separation techniques, bioreactor types, fermentation conditions, gas–liquid mass transfer, current status of the technology and economics. It seems selection of the appropriate microorganism, nutrient medium, and appropriate hollow fiber membrane biofilm reactor might lead toward achieving an increased mass transfer efficiency for commercialization of the bioethanol.