Climate and biodiversity impacts of low-density polyethylene production from CO2 and electricity in comparison to bio-based polyethylene.

Plastics are essential materials for modern societies, but their production contributes to significant environmental issues. Power-to-X processes could produce plastics from captured CO2 and hydrogen with renewable electricity, but these technologies may also face challenges from environmental perspective. This paper focuses on environmental sustainability assessment of CO2-based low-density polyethylene (LDPE) compared to bio-based LDPE. Life cycle assessment has been applied to study climate impacts and land use related biodiversity impacts of different plastic production scenarios. According to the climate impact results, the carbon footprint of the produced plastic can be negative if the energy used is from wind, solar, or bioenergy and the carbon captured within the plastic is considered. In terms of biodiversity, land-use related biodiversity impacts seem to be lower from CO2-based polyethylene compared to sugarcane-based polyethylene. Forest biomass use for heat production in CO2-based polyethylene poses a risk to significantly increase biodiversity impacts. Taken together, these results suggest that CO2-based LDPE produced with renewable electricity could reduce biodiversity impacts over 96 % while carbon footprint seems to be 6.5 % higher when compared to sugarcane-based polyethylene.

Scaling up continuous ultrasound-assisted extractor for plant extracts by using spinach leaves as a test material.

The ultrasound-assisted extraction (UAE) process of chlorophylls (a, b) and carotenoids in aqueous ethanol solutions from spinach leaves was upscaled from a batch laboratory reactor to a continuous modular flow-cell of pilot scale. The extraction in the laboratory scale was organized in a loop reactor, where pulp was circulated between a stirred vessel and the ultrasound reactor. The pilot scale extraction was made in a novel continuous tubular flow-cell reactor. The analysis of the experimental data proved that the ultrasound application provided a better extraction yield. In the laboratory scale, the application of ultrasound (24 kHz and 2500 W/L) showed the 2.6-fold higher maximum extraction yield compared to non-sonicated conventional solvent extraction. In the pilot scale, the effect was less significant (1.9-fold), due to smaller ultrasound power density (25 kHz and 1500 W/L). The scale-up of the UAE was based on equal extraction yield at both scales. The scale-up revealed that 2.5-fold higher volume-specific ultrasound power is required in the pilot scale to reach the yield obtained in the laboratory scale reactor.

Monitoring and Visualization of Crystallization Processes Using Electrical Resistance Tomography: CaCO3 and Sucrose Crystallization Case Studies.

In the current research work, electrical resistance tomography (ERT) was employed for monitoring and visualization of crystallization processes. A first-of-its-kind MATLAB-based interactive GUI application "ERT-Vis" is presented. Two case studies involving varied crystallization methods were undertaken. The experiments were designed and performed involving calcium carbonate reactive (precipitative) crystallization for the high conductivity solution-solute media, and the cooling crystallization of sucrose representing the lower conductivity solution-solute combination. The software successfully provided key insights regarding the process in both crystallization systems. It could detect and separate the solid concentration distributions in the low as well as high conductivity solutions using the visual analytics tools provided. The performance and utility of the software were studied using a software evaluation case study involving domain experts. Participant feedback indicated that ERT-Vis software helps by reconstructing images instantaneously, interactively visualizing, and evaluating the output of the crystallization process monitoring data.

Real-Time Fault Detection and Diagnosis of CaCO3 Reactive Crystallization Process by Electrical Resistance Tomography Measurements.

In the present research work, an electrical resistance tomography (ERT) system is utilized as a means for real-time fault detection and diagnosis (FDD) during a reactive crystallization process. The calcium carbonate crystallization is part of the carbon capture and utilization scheme where process monitoring and malfunction diagnostics strategies are presented. The graphical logic representation of the fault tree analysis methodology is used to develop the system failure states. The measurement consistency due to the use of a single electrode from a set of ERT electrodes for malfunction identification is experimentally and quantitatively investigated based on the sensor sensitivity and standard deviation criteria. Electrical current measurements are employed to develop a LabVIEW-based process automation program by using the process-specific knowledge and historical process data. Averaged electrical current is correlated to the mechanical failure of the stirrer through standard deviation evaluation, and slopes of the measured data are used to monitor the pump and concentrations status. The performance of the implemented methodology for detecting the induced faults and abnormalities is tested at different operating conditions, and a basic signal-based alarming technique is developed.

An Ultrasound Tomography Method for Monitoring CO2 Capture Process Involving Stirring and CaCO3 Precipitation.

In this work, an ultrasound computed tomography (USCT) system was employed to investigate the fast-kinetic reactive crystallization process of calcium carbonate. USCT measurements and reconstruction provided key insights into the bulk particle distribution inside the stirred tank reactor and could be used to estimate the settling rate and settling time of the particles. To establish the utility of the USCT system for dynamical crystallization processes, first, the experimental imaging tasks were carried out with the stirred solid beads, as well as the feeding and stirring of the CaCO3 crystals. The feeding region, the mixing process, and the particles settling time could be detected from USCT data. Reactive crystallization experiments for CO2 capture were then conducted. Moreover, there was further potential for quantitative characterization of the suspension density in this process. USCT-based reconstructions were investigated for several experimental scenarios and operating conditions. This study demonstrates a real-time monitoring and fault detection application of USCT for reactive crystallization processes. As a robust noninvasive and nonintrusive tool, real-time signal analysis and reconstruction can be beneficial in the development of monitoring and control systems with real-world applications for crystallization processes. A diverse range of experimental studies shown here demonstrate the versatility of the USCT system in process application, hoping to unlock the commercial and industrial utility of the USCT devices.

Gas phase methanol synthesis with Raman spectroscopy for gas composition monitoring.

Applicability of Raman spectroscopy for time-resolved gas composition monitoring during direct methanol synthesis via carbon dioxide hydrogenation was investigated. A series of methanol synthesis experiments with varied reactor conditions was conducted and the reactor outlet stream was analyzed with in-line gas Raman spectroscopy. Concentrations of H2, CO2 and CO were determined directly from the acquired spectral data. For evaluation of methanol and water content a data reconciliation algorithm was developed. The algorithm involves estimation of the occurring chemical reactions' extents by iterative minimization of the difference between concentration values acquired from the experimental data and concentration values computed based on the mass conservation principle. The obtained experimental concentrations were compared and validated against the results of the reactor mathematical modeling, which is based upon a well-established kinetic interpretation of the process. The findings indicate good repeatability and accuracy of the developed gas analysis system, which together with the advantageous temporal resolution of the method, make Raman spectroscopy a promising technique for fast response monitoring of the process.

Low concentrated carbonaceous suspensions assisted with carboxymethyl cellulose as electrode for electrochemical flow capacitor.

The search for efficient energy storage devices has recently led to the introduction of a fluid electrode material employing electrochemical flow capacitors (EFC). Unlike the classical solid electrode film containing capacitors, where the electrode material is fixed to the current collectors and capacitance is therefore limited with an active surface area of porous electrode, the flow electrodes offer new design opportunities which enable fully continuous charging/discharging processes as well as easily scalable systems. Here we describe the successful incorporation of the carboxymethyl cellulose sodium salt (CMC-Na) assisted carbonaceous suspension electrode in aqueous media for the electrochemical flow capacitor concept and demonstrate the electrochemical charge storage in flowable electrodes using a cation conductive membrane as separator in a double-pipe flow-electrode module. Experimental results were combined with computer simulations (FEM) to specify limiting processes EFC charging. The flow-electrode slurry is based on 0.1 M Na2SO4, 3 wt% CMC-Na and activated carbon powder suspended in water. During continuous operation of the system, the capacitance of the flow electrode reached to 0.3 F/L providing the energy and current densities of 7 mWh/kg and 56 mW/L, respectively. Additionally, we report a 70% round trip efficiency calculated during charging and discharging of the cell between 0 V and +0.75 V, while applying the current density of 1.6 mA/kg. The double-pipe flow-electrode module is easily expandable for transportation of large volumes of electrode material.

Numerical Simulation of Biomass Growth in OKTOP®9000 Reactor at Industrial Scale.

Computational fluid dynamics is a powerful method for scale-up of reactors although it is still challenging to fully embrace hydrodynamics and biological complexities. In this article, an aerobic fermentation of Pichia pastoris cells is modeled in a batch OKTOP®9000 reactor. The 800 m3 industrial scale reactor is equipped with a radial impeller, designed by Outotec Oy for gas dispersion in the draft tube reactor. Measured N p of the impeller is used in hydrodynamics validation. The resolved energy dissipation rate is compensated, and its influence on mass transfer is analyzed and discussed. Gas-liquid drag force is modified to simulate effects of liquid turbulence and bubble swarms. Resolved steady state multiphase hydrodynamics is used to simulate the fermentation process. Temporal evolution of species concentrations is compared to experimental data measured in a small copy of the reactor at lab scale (14 L). The effect of oxygenation on the P. pastoris cells cultivation is considered.

Erratum: Demesa, A.G.; et al. Valorization of Lignin by Partial Wet Oxidation Using Sustainable Heteropoly Acid Catalysts. Molecules 2017, 22, 1625.

The authors would like to make the following correction to their published paper [1]. [...].

Natural cellulose ionogels for soft artificial muscles.

Rapid development of soft micromanipulation techniques for human friendly electronics has raised the demand for the devices to be able to carry out mechanical work on a micro- and macroscale. The natural cellulose-based ionogels (CEL-iGEL) hold a great potential for soft artificial muscle application, due to its flexibility, low driving voltage and biocompatibility. The CEL-iGEL composites undergo reversible bending already at ±500mV step-voltage values. A fast response to the voltage applied and high ionic conductivity of membranous actuator is achieved by a complete dissolution of cellulose in 1-ethyl-3-methylimidazolium acetate [EMIm][OAc]. The CEL-iGEL supported cellulose actuator films were cast out of cellulose-[EMIm][OAc] solution via phase inversion in H2O. The facile preparation method ensured uniform morphology along the layers and stand for the high ionic-liquid loading in a porous cellulose scaffold. During the electromechanical characterization, the CEL-iGEL actuators showed exponential dependence to the voltage applied with the max strain difference values reaching up to 0.6% at 2 V. Electrochemical analysis confirmed the good stability of CEL-iGEL actuators and determined the safe working voltage value to be below 2.5V. To predict and estimate the deformation for various step input voltages, a mathematical model was proposed.

Valorization of Lignin by Partial Wet Oxidation Using Sustainable Heteropoly Acid Catalysts.

The production of carboxylic acids by partial wet oxidation of alkali lignin at elevated temperatures and pressures was studied experimentally. Two different heteropoly acids, phosphotungstic acid (H3PW12O40) and phosphomolybdic acid (H3PMo12O40), were used to catalyze the oxidation of lignin under hydrothermal conditions. Factors influencing the total yield of carboxylic acids formed during the partial oxidation of lignin were investigated. Formic, acetic and succinic acids were the major products identified. Of the two catalysts used, phosphomolybdic acid gave the most promising results, with carboxylic acid yields and lignin conversions of up to 45% and 95%, respectively.