Landfill leachate contains a variety of compounds, many of which are chemically and biologically recalcitrant. The aim of this study was to convert a batch/semicontinuous reactor into a continuous ...tubular reactor for catalytic ozonation of landfill leachate with Fe2+ and develop a kinetic model for the degradation of organic carbon in leachate. The reaction volume was kept constant throughout the experiments by controlling the inflow of air, ozone, and catalyst solution and the outflow of foam. The kinetic model revealed TOC scission rate constants ranging from 3.5 × 106 to 4.45 × 107 L mol–1 s–1 and showed good predictive capacity (R 2 = 0.9999). The use of a continuous reactor for catalytic ozonation and the kinetic model developed for the degradation of organic carbon in landfill leachate are innovations that can provide important technical information to support process scale up. For instance, the developed model was able to predict the amount of reagent and the operating conditions that are necessary to achieve a specific level of TOC removal, which is essential information to design a full-scale system for treating landfill leachate.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
In this article, we have reported the electrochemical reduction of CO2 in a continuous semi-micro reactor for the synthesis of formic acid (HCOOH). The reactor was fabricated with ...polydimethylsiloxane by following the microwire molding technique. Tin (Sn) nanocatalyst-deposited graphite rod was used as the cathode for the electrochemical reduction of CO2 to HCOOH. We performed the reactions in an alkaline environment at different pH values and different applied voltages for 1200 s to obtain an optimum condition for HCOOH production. The maximum Faradaic efficiency (FE) values of 84.25 and 57.69% were obtained at 2.5 and 3 V, respectively, after 300 s at an initial pH value of 9.5. It was found that the continuous reactor showed higher FE values than the batch reactor. It was also noted that the HCOOH concentration in the batch reactor was continuously decreasing with time, whereas it was almost constant in the continuous semi-micro reactor.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
This work presents the effect of autoclave, microwave and ultrasonication pretreatment on anaerobic digestion of food waste co-digested with poultry manure. Four batch reactors with 2 L volume each ...were used for the study. The reactors were operated with a hydraulic retention time of 30 days and stirred twice a day. The daily biogas production, cumulative biogas production, methane and carbon dioxide composition were measured. The pretreatment of the substrates with autoclave, microwave and ultrasonication caused an increase in cumulative biogas production of approximately 4.67, 6.43 and 10.12% respectively. The degradation efficiency also showed positive result for substrates with pretreatment. The highest cumulative biogas yield was obtained with ultrasonication technique (9926 ml), followed by autoclave, microwave and untreated substrates. The results obtained from the experiments were evaluated to determine the kinetic constants of the process. Modified Gompertz model and Logistic model were used to determine the kinetic parameters of the reaction. The results obtained with the modified Gompertz model was more suitable than the result obtained with the Logistic model for describing the process kinetics.
Display omitted
•Effects of different pretreatment on anaerobic digestion of food waste co-digested with poultry manure were studied.•All the three pretreatment techniques have significant effects on biogas production.•Ultrasonication showed the best results in terms of biogas production and degradation efficiency.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Display omitted
•Identification of NH3-LCFA synergetic effect in batch and continuous reactors.•A new mechanism was proposed to explain the NH3-LCFA synergetic effect.•Excess LCFA levels due to ...β-oxidation inhibition by NH3 trigger the synergism.•Adaptation of the microbiome to the synergism is possible in continuous reactor.•Different NH3-LCFA levels cause the synergism in batch and continuous reactors.
Ammonia and long chain fatty acids (LCFA) are two major inhibitors of the anaerobic digestion (AD) process. The individual inhibitory effect of each of these two inhibitors is well established; however, the combined co-inhibition effect has not been thoroughly assessed yet. In the current study, the ammonia-LCFA synergetic co-inhibition effect was investigated in both batch and continuous experiments. In the batch experiments, a clear ammonia-LCFA synergetic co-inhibitory effect was identified when the LCFA concentrations were higher than 0.05 g oleate L−1 and ammonia levels between 4.0 and 7.0 NH4+-N L−1. This synergetic effect for LCFA and ammonia levels above 1.1 g oleate L−1 and 4.5 NH4+-N L−1, respectively, was validated in continuous reactors experiments. Nevertheless, adaptation of the AD microbiome to this synergetic co-inhibition could occur after a period of continuous operation. A potential mechanism to explain the synergetic co-inhibition lies on the initial inhibition of methanogens caused by ammonia resulting in increased VFA and hydrogen concentrations, which in turn renders β-oxidation of LCFA thermodynamically unfavourable and thereby brings about further excess accumulation of LCFA and consequently higher unspecific toxicity of all AD steps. This is a vicious cycle, which makes the combined inhibition of the two toxicants more severe, compared to the sum of their individual inhibition effects at the same operational conditions.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A scalable flow reactor is demonstrated for enantioselective and regioselective rhodium carbene reactions (cyclopropanation and C−H functionalization) by developing cascade reaction methods employing ...a microfluidic flow reactor system containing immobilized dirhodium catalysts in conjunction with the flow synthesis of diazo compounds. This allows the utilization of the energetic diazo compounds in a safe manner and the recycling of the dirhodium catalysts multiple times. This approach is amenable to application in a bulk‐scale synthesis employing asymmetric C−H functionalization by stacking multiple fibers in one reactor module. The products from this sequential flow–flow reactor are compared with a conventional batch reactor or flow–batch reactor in terms of yield, regioselectivity, and enantioselectivity.
Even flow: A scalable flow reactor for enantioselective and regioselective rhodium carbene reactions has been achieved. Cascade reaction methods were employed in a microfluidic flow reactor system containing immobilized dirhodium catalysts in conjunction with the flow synthesis of diazo compounds.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•Heterogeneous catalysis in continuous flow microreactors has been reviewed.•Microreactor technology can aid process intensification.•Various catalyst immobilization procedures are ...discussed.•Meso-reactors with multi-phase flow show growing potential as synthesis tools.
Over the past two decades, microreactor technology has evolved to become a crucial component in the development of process intensification. Microreactors have helped to minimize reagent consumption and energy waste due to their small dimensions, which in most cases do not exceed 1mm in at least one dimension. The small volume of microreactors enables safe handling of even hazardous or highly exothermic reactions while facilitating fast and easy parameter screening. As a consequence of the small size, the ratio of surface area to volume is much higher than in conventional reactors. This in turn affects other properties such as the flow regime, and mass and heat transfer. Because high pressure and temperature can be handled much easier at a very small scale, microreactors unlock new process windows. If a catalyst is deposited inside the microreactor in the form of a thin coating or a monolith, these devices may have great prospects in heterogeneous catalysis spanning from petrochemical to pharmaceutical applications. In this tutorial review, different methodologies to immobilize heterogeneous catalysts in microreactor structures have been collected, and applications for process development, data generation, and synthesis in continuous flow have been critically assessed.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Synthetic natural gas (SNG) production via methanation is numerically investigated.•Methanation is sensitive to the reaction temperature.•Hot spot in the reactor causes decreases in CO conversion ...and CH4 yield.•Best CO conversion can be obtained from isothermal reactor.•Enhanced H2/CO ratio is required for SNG production using syngases as feedstock.
The synthetic natural gas (SNG) production via methanation reaction was investigated in this study. A fixed-bed tubular reactor was used as the physical model and axisymmetric non-isothermal governing equations for the gas flow, energy transfer and species transport were solved numerically. The operating conditions (inlet pressure, inlet temperature, feed rate, and heat transfer) and the reactant gas composition effects on the reaction were studied. CO conversion, CH4 yield, H2 efficiency and CO2 yield were used to characterize the reaction performance. It was found that CO methanation is sensitive to the reaction temperature. Based on the operating conditions used in this study, CO conversion from 0% at reactant inlet temperature (Tin) of 300°C abruptly increases to 100% at Tin=380°C. As Tin is greater than 380°C, a hot spot exists in the reactor, leading to decreases in CO conversion and CH4 yield. It was also found that under the same operating condition, 60% decrease in CO conversion could result from an adiabatic reactor compared with the isothermal reactor. CO conversion and CH4 yield can be enhanced by increasing the reaction pressure and H2/CO ratio, and decreasing the space velocity. With the addition of product species (CH4, CO2, and H2O) as the reactants, a decrease in CO conversion was found except for the addition of H2O. It was found that the CH4 yield was decreased by product species addition.
Low CO conversion and CH4 yield were obtained when coal- or biomass-derived syngas was used as the feedstock for methanation reaction due to low H2/CO ratio. To enhance SNG production via syngas methanation, it is suggested that the water-gas shift reaction be employed to increase the H2/CO ratio before carrying out methanation reaction.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Continuous-flow chemistry is emerging as an enabling technology for the synthesis of precise polymers. Recent advances in this rapidly growing field have hastened a need for a fundamental ...understanding of how fluid dynamics in tubular reactors influence polymerizations. Herein, we report a comprehensive study of how laminar flow influences polymer structure and composition. Tracer experiments coupled with in-line UV–Vis spectroscopy demonstrate how viscosity, tubing diameter, and reaction time affect the residence time distribution (RTD) of fluid in reactor geometries relevant for continuous-flow polymerizations. We found that the breadth of the RTD has strong, statistical correlations with reaction conversion, polymer molar mass, and dispersity for polymerizations conducted in continuous flow. These correlations were demonstrated to be general to a variety of different reaction conditions, monomers, and polymerization mechanisms. Additionally, these findings inspired the design of a droplet flow reactor that minimizes the RTD in continuous-flow polymerizations and enables the continuous production of well-defined polymers at a rate of 1.4 kg/day.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
OMTP solar photoreactor scheme (design using Sketchup®).
Display omitted
•A Novel Prototype Offset Multi Tubular Photoreactor (OMTP) was developed.•The OMTP is a simple modification of the compound ...parabolic collector (CPC).•The reactor volume of the OMTP is up to 80% higher than the CPC for the same footprint.•OMPT achieve significantly higher degradation efficiency of organic contaminant that CPC reactor.•The OMTP should outperform the CPC in environmental and renewable energy applications.
The design and operation of a new solar photoreactor prototype named Offset Multi Tubular Photoreactor (OMTP) is presented. The OMTP advances over the compound parabolic collector (CPC) photoreactor, which is one of the most efficient design for large-scale solar detoxification of water and wastewater. The OMTP design is based on a simple modification of the common CPC and included a supplementary set of tubes in the space occupied by the axes of intersection of the CPC reflective involutes. This new reactor configuration increased the irradiated reactor volume by 79% and the fluid residence time by up to 1.8-fold in comparison to the CPC, for the same solar irradiated area (footprint). The model parameters used for comparing and scaling the OMPT and CPC were β (reactor volume/total volume), α (area of absorption/total volume), αg (physical area/total volume), degradation efficiency ηα per unit area, and the operating volume. The total solar energy absorbed in the reactors (1.74 m2 footprint) was 15.17 W for the CPC and 21.86 W for the OMTP, which represents an overall gain of 44% for the latter. The performance of the OMTP and CPC were compared at the same value of solar exposure, β of 0.3 with optimal photocatalyst loading of 0.25 g/L titanium dioxide (TiO2 P25). The degradation efficiencies of methylene blue, dichloroacetic acid, 4-chlorophenol (120 ppm initial concentration) in the OMTP were up to 81%, 125%, 118% and 242% higher, respectively, in comparison to the CPC after 8000 J/m2 of accumulated solar energy. The OMTP should outperform the CPC in environmental and renewable energy applications of solar heterogeneous photocatalysis.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Microfluidic device demonstrated potential to replace common analytical instrument.•Microreactor is regarded as a critical functional unit for microfluidic system.•Recent biomedical progress of ...microreactor in the past five years was reviewed.
Lab-on-a-chip has evolved into a powerful analytical tool that combines multiple disciplines for biomedical research. The microfluidic reactor in lab-on-a-chip is regarded as a critical functional device and has a direct impact on the performance of the entire lab-on-a-chip system. The rich and flexible design allows the microfluidic reactor to be used for reactions in a micromixing channel or inside the common microchannel/chamber at a microscale. Moreover, a variety of microfluidic reactors could be utilized in the field of biomedical analysis with a high reaction rate and less reagent consumption. This paper reviewed the delicate design principle of microfluidic reactors (mixing and ordinary reactors). The biomedical applications of mixing reactor (reaction kinetics research and preparation of nanoparticle drug carriers) and the mature applications of other types of microreactor (on-chip polymerase chain reaction, enzyme-linked immunosorbent assay, and nucleic acid hybridization) were introduced in detail. Commonly utilized detection technologies (laser-induced fluorescence, light absorption measurement, and electrochemical) and low-cost on-chip detection strategies were summarized in detail. This review may shed light on the design and application of microfluidic reactor in the biomedical area.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
PDF
