The rapid expansion of supercritical solution (RESS) technology was used in this study to re‐crystalize and micronize three active pharmaceutical ingredients (APIs) of monobenzone, ethylparaben and kojic acid. All unprocessed APIs (denoted as the original APIs in the following manuscript) had large mean particle size over 200 𝜇m with wide particle size distribution. Supercritical carbon dioxide was used as the solvent to extract each API in a high pressure vessel. The nearly saturated supercritical solution was then expanded through a capillary spray nozzle to ambient pressure state. The APIs were re‐crystallized in a very short time period. The final API particles with submicron sizes were obtained with much less intensity of crystallinity. The optimal RESS process parameters and the improved result of the in vitro dissolution test for the API of ethylparaben are reported.

A hybrid fluidized‐bed bioreactor for water purification was proposed and analyzed. It is a novel type of bioreactor characterized by hitherto unknown stationary and dynamic features. Steady‐state characteristics of this hybrid bioreactor with external liquid circulation are presented. A quantitative analysis of steady‐state properties of the bioreactor was performed with the aid of original mathematical model developed for a double‐substrate aerobic microbiological process. A steady‐state analysis of aerobic processes characterized by different oxygen demand was performed. The effect of essential parameters was evaluated, including carbonaceous substrate concentration in the feed stream to the apparatus, aeration intensity, total residence time of a liquid in the bioreactor and height of the bed of fine carrier particles.

The separation of oil, water and sand has always been a difficult problem in the treatment of oily sludge in oil field and petroleum refinery. This article is devoted to the analysis of flow field and separation performance in a new three‐phase decanter centrifuge with vertical boards and annular liquid separation plate for oil‐water solids separation, using the CFD software Fluent with Euler‐Euler three‐phase flow model, which provides a basis for the improvement and optimization of the centrifuge. After calculation, the velocity and pressure field were analyzed. The increase of solids content of the feed will affect the separation efficiency regularly, and high or low treatment capacity will also have a certain impact on the separation efficiency.

This study deals with nanobubble generator using honeycomb structures producing a large amount of water including large nanobubble density in a short time. Here, the nanobubble generating performance is investigated for large and small apparatus having different honeycomb cell dimensions by applying a computational fluid dynamics (CFD) coupled with a population balance model (PBM). The CFD simulation shows significant pressure drop and shear stress occur in the bubbly flow in the honeycomb cell. The numerical model is based on the Eulerian multiphase model and the PBM is used to calculate the bubble size distribution. The obtained CFD‐PBM results are compared with the experimental results for large and small apparatus. The results show that bubble size distributions in the honeycomb structure under different inlet absolute pressure can be predicted by the PBM. It may be concluded that the maximum shear stress is the main controlling factor for the nanobubble generation.

The hydrodynamics and volumetric mass transfer coefficients play important role in the design and scale‐up of airlift reactors. In the present study, the effect of surface tension has been analysed on hydrodynamics and volumetric mass transfer coefficient in internal loop airlift reactors. It is observed that with decrease in surface tension of the fluid, the hydrodynamic parameters (gas phase holdup, flow regime transition point, interfacial area) increased whereas bubble diameter as well as liquid velocity decreased while the volumetric mass transfer coefficient increased. The empirical correlations have proposed for gas phase holdup and volumetric mass transfer coefficient in terms of dimensionless numbers and can be used in design of airlift reactors.

The reactive dividing wall column (RDWC) presents a highly integrated process that enables significant reductions in investment costs and energy consumption. However, the high degree of integration of this apparatus causes numerous interactions between kinetics, vapor‐liquid‐equilibrium and mass transfer. To ensure a reliable operation of the RDWC suitable control schemes need to be developed and experimentally validated. In this work a decentralized control scheme for the RDWC is presented and for the first time experimentally investigated on an RDWC pilot plant. A comparison of experimental and simulated data is carried out and shows good agreement.

Continuous flow separation and recovery of silver nanoparticles is demonstrated using an annular centrifugal extractor. Separation was achieved at the liquid‐liquid interface based on the balance between centrifugal force and the solubility of the capping agent. A mathematical model is presented to understand the mechanism in greater detail in batch. The same principles were extended for carrying out the separation of PVP coated silver nanoparticles in continuous flow using the annular centrifugal extractor using a heavy immiscible solvent to remove excess PVP and to allow development of a stable interface where nanoparticles get accumulated over a period of time while the aqueous and organic phases exit from the extractor. The material accumulated at the interface can be separated periodically without discontinuing the operation. The analysis of experimental data and also the observations from the model indicated that the approach would need multiple annular centrifugal extractors in series for complete recovery of small sized nanoparticles. The method is also suitable for separation of large particles or 1D/2D nanostructures or in the case of less viscous suspensions even using a single annular centrifugal extractor. The suitability of these stable silver nanoparticles was achieved by washing off excess PVP and the resulting increased surface activity was verified by carrying out a detailed antimicrobial activity study.

The organosulfur compounds deactivate the catalysts used during downstream processing of petroleum and also responsible of SOx during fuel combustion. In the current study, adsorption of dibenzothiophene (DBT) from model oil was investigated using composites of pure activated charcoal and pure bentonite clay. DBT adsorption was carried out in batch mode experiments at laboratory scale, where the developed composite materials shown synergistic effect in removal of DBT from model oil. The present work demonstrate the combined effect of prepared composite such as improved surface acidity of pure activated charcoal and mesoporous structure of pure bentonite clay. Experiments were conducted to study the thermodynamics, kinetics and optimization of various adsorption parameters such as contact time, adsorbent dosage, temperature and initial DBT concentration. Optimum conditions for maximum removal of DBT (97.22%) were found to be 0.75 g of adsorbent, 60 minutes contact time, 55°C temperature and 300 ppm of initial DBT concentration. Kinetic investigations shown that DBT adsorption follow pseudo second order kinetics, with rate constant of 0.00578 g/(mg. min). To study the thermodynamics of the adsorption, different isotherm adsorption models were applied, and it was found that Langmuir isotherm was best fitted to the adsorption data. Various thermodynamic parameters also evaluated, including Gibbs free energy, entropy, and enthalpy to conclude the study objectives.

Carboxyl graphene (CG) with two functions of hybridization and crosslinking was incorporated into poly(vinyl alcohol) (PVA) matrix to form PVA/CG mixed matrix membranes (MMMs). The membranes demonstrated excellent mechanical properties and thermal stability. The improved hydrophilicity and formed crosslinking structure led to moderate swelling. The membrane crystallinity decreased and the free volume was promoted with increasing CG loading amount. The pervaporation (PV) separation performance for ethanol dehydration indicated that both permeation flux andseparation factor were enhancedsimultaneously at the optimum CG loading. Subsequently, the permeation flux continued to increase while the separation factor declined at higher CG loadings.

Very good extraction selectivity of Cu2+ from water by employing bis(2‐ethylhexyl) phosphate acid (D2EHPA) as an extractant and kerosene as a solvent with a new micro‐channel equipment was demonstrated. The effects of different experimental parameter on extraction efficiency (E%), volumetric mass transfer coefficient () and entrainment were experimentally investigated. The results showed that extraction efficiency increased with the increase of temperature, concentration of the extractant, phase ratio(O/A) and pH. The total flow rate, phase ratio(O/A) and pH were found to have great effect on. The temperature and concentration of the extractant, however, showed little effect on the mass transfer.

Nano‐tin oxide grafted natural‐hydroxyapatite photocatalyst was fabricated using a greener approach involving sequential application of solar‐type and ultrasound‐wave energy (STUWE). The protocol ensued 76% higher surface area, 59% more surface acidity and 15% reduced band gap energy than conventionally prepared photocatalyst (CPPC). The efficacy of STUWE promoted photocatalyst (STUWEPC) was optimized for maximization of 2‐ethylhexyl acetate yield (97%) employing energy‐efficient solar (type)‐ultrasound synergistic batch reactor. Noticeably, a considerably lower (38.34%) activation energy (estimated by Langmuir‐Hinshelwood kinetics) and higher reusability characteristics (98±1% consistent acetic acid conversion after 8th cycle) of STUWEPC than CPPC, highlights the supremacy of STUWE protocol.

The aim of this work was to prepare water‐in‐oil‐in‐water (w/o/w) emulsions using commonly available raw materials and a two‐step emulsification process. Several combinations of milk proteins and hydrocolloids were tested as internal water phases. Emulsions prepared with milk or colostrum exhibited the highest encapsulation efficiencies. In particular, w/o/w emulsions with internal water phases composed of colostrum, without addition of hydrocolloids, were the most stable. However, the addition of xanthan gum proved to be synergistic in stabilising w/o/w whey emulsions.

Waste organic biomass is regarded as the most suitable renewable source for conversion to produce biofuels and biochemicals. Owing to its high‐energy potential and abundancy, lignocellulosic biomass can be utilized to produce alternative energy in the form of gaseous and liquid biofuels. Microbial conversion of waste biomass is found to be the most successful technology for the generation of biohydrogen through dark fermentation. Hydrogen is considered as the promising renewable green energy source for a sustainable future. Different biological hydrogen production technologies along with process parameters are described in this review paper although the emphasis is on dark fermentation. The production of biohydrogen from various substrates are summarized in this article along with the integrated mode of dark fermentation and photo‐fermentation. Hydrogen generation through biological water‐gas shift reaction is also highlighted.

The chemical looping steam methane reforming (CL‐SMR) process has two stages: the reduction of oxygen carrier with methane and oxidation of the reduced oxygen carrier by water splitting reaction. In the present research, the reduction stage of the CL‐SMR was investigated at temperature range of 700‐900 ºC to determine the kinetics of the reduction reaction for CeO2‐Fe2O3 mixed oxides. CeO2, Fe2O3 and CeO2‐Fe2O3 mixed oxides with different molar ratios were prepared by chemical precipitation method. From the characterization tests, the lowest BET surface area belonged to the samples with more Fe content. The highest area under reduction peaks during the H2‐TPR measurements was also related to the samples with highest Fe content. From SEM images, these two aforementioned samples had the largest particle size compared to other ones. Reduction of the oxygen carriers with lower Fe content was well represented by phase boundary controlled model. Also, the first order and diffusion controlled models were successfully applied to predict the experimental data for S6 (Fe/Ce = 9/1) and S7 (Fe2O3), respectively, that had the highest Fe content. The activation energy for S5 (Fe/Ce = 7/3) which showed the highest yield was 81 kJ/mol. Also, the activation energies were in the range of 60‐285 kJ/mol for other oxygen carriers.

Dry tray pressure drop (ΔPd) is a design parameter that supplies preliminary information about total pressure drop. This work aimed to assess correlations for ΔPd prediction for different types of trays without downcomer and to evaluate the effect of free area ratio (φ) and hole diameter (d) on ΔPd. Assessment was performed comparing results of several correlations with those from a computational fluid dynamics simulation experimentally validated. The study shows that the correlations of Červenka and KoláŘ, Bennett, Agrawal and Cook and Stichlmair and Mersmann predicted dry pressure drop satisfactorily. The Bennett, Agrawal and Cook correlation can be recommended for the prediction of ΔPd for a wide range of geometries and operation conditions. Also, φ has a higher influence on ΔPd than d.

The use of CO2 as a raw material is increasingly important as an option for climate protection and as an alternative raw material feedstock. Both electrochemical direct syntheses and thermochemical processes are associated with a high demand for electrical energy. A contribution to climate protection is only possible in the case of low‐carbon power generation, as can be achieved, for example, by wind power or solar energy. This article presents a methodology for identifying suitable locations for the CO2‐based production of olefins in Germany. Based on electricity and CO2 requirements, locations are identified that can provide sufficient CO2 and renewable energy for the conversion of CO2 to olefins. In addition, the use of existing infrastructures is taken into account. The analysis shows that the regional, technical renewable energy potential in Germany is sufficient to produce around approximately 800 kt of olefins from CO2‐based methanol per year in one plant. This plant capacity corresponds to the currently largest methanol‐to‐olefins plant in the world. On the other hand, the currently available CO2 point sources with high CO2 concentrations of around 100 % are not sufficient to meet the CO2 requirement of an 800 kt/a methanol‐to‐olefins plant. Therefore, much larger CO2 point sources such as coal‐fired power plants or steel mills with lower CO2 concentrations of less than 35 % are needed. If existing refineries are preferred due to existing infrastructure services, locations in the north of Cologne, in Lower Saxony and in Brandenburg are particularly suitable. The analysis also shows that a full substitution of fossil olefins by CO2‐based olefins is possible in Germany. The challenge is to provide sufficient renewable electricity of more than 244 TWh/a for the production of H2 with a low CO2 intensity.

This paper investigates the cleaning effect of a high‐pressure jet of water on a polymeric microfiltration membrane at different pressures, durations and angles. The angle of 70° at a pressure of 130 bar and a cleaning duration of 10 seconds were found to be promising parameters. Measurements of the throughput show that this cleaning method can restore about 80% of the initial throughput of the membrane. Analyses of the capillary flow porometer and the UV‐vis spectrophotometer imply that an impact of the membrane was caused after 1800 cleaning cycles at a pressure of 130 bar. Therefore, high‐pressure jet cleaning is a promising method for mechanical cleaning of track‐etched microfiltration membranes.

No abstract.