Heterogeneous Slurry Research Articles

Comonomer-controlled synthesis of long-chain branched (LCB)-polyethylene

In this contribution, we disclose the ability of α,ω-diene comonomers, namely 1,7-octadiene and 1–10-undecadiene, as long-chain branching (LCB)/cross-linking promoters in the ethylene polymerization catalyzed by bis(indenyl) and bis(cyclopentadienyl) catalyst systems, namely rac-{EBTHI}ZrCl2 (Zr-1) and (nBuCp)2ZrCl2 (Zr-2). Both under homogeneous and heterogeneous (slurry) conditions, Zr-1-based systems efficiently produced LCB/cross-linked polymers even with very small amounts of diene, as demonstrated by melt rheology measurements. On the other hand, higher co-monomer concentrations were required for the homogeneous Zr-2/MAO system, while only linear PEs were isolated in the presence of its silica-supported version supp-Zr-2 operated under heterogeneous conditions, regardless of the amount of diene employed. Rheological and NMR spectroscopy studies proved that consumption of the diene and formation of LCB/cross-linked structures take place during the early stages of the polymerization. The experimental observations were rationalized by DFT computations.

Role of Low Molecular Weight Polymers on the Dynamics of Silicon Anodes During Casting.

This work probes the slurry architecture of a high silicon content electrode slurry with and without low molecular weight polymeric dispersants as a function of shear rate to mimic electrode casting conditions for poly(acrylic acid) (PAA) and lithium neutralized poly(acrylic acid) (LiPAA) based electrodes. Rheology coupled ultra-small angle neutron scattering (rheo-USANS) was used to examine the aggregation and agglomeration behavior of each slurry as well as the overall shape of the aggregates. The addition of dispersant has opposing effects on slurries made with PAA or LiPAA binder. With a dispersant, there are fewer aggregates and agglomerates in the PAA based silicon slurries, while LiPAA based silicon slurries become orders of magnitude more aggregated and agglomerated at all shear rates. The reorganization of the PAA and LiPAA binder in the presence of dispersant leads to a more homogeneous slurry and a more heterogeneous slurry, respectively. This reorganization ripples through to the cast electrode architecture and is reflected in the electrochemical cycling of these electrodes.

Photocatalytic Decolorization Simulated Textile Dyebath Effluent under Solar Light and Reuse it for Industrial Propose

In this work, the photocatalytic is related to simulated wastewater as well as recycling for industrial uses. Photocatalytic degradation of simulated wastewater content (Eosin Yellowish, Eriochrom Black T, Methyl Violet, EDTA, FeSO4.7H2O, NaCl, and NaOH) was utilized as a treatment approach in batch reactors within solar light in a heterogeneous slurry with the use of many concentrations regarding the commercial powder ZnO as photocatalysts semiconductors. We have tested many operation conditions like (catalyst concentration, pH, initial dye concentration and final water treated properties). The water quality related to treated wastewater is based on the nature of waste added during usage, the industrial water supply quality, and the treatment degree which is received via wastewater. After that, the quality data of wastewater is evaluated and indicated at waste-water treatment plant majorly for the disposal of the treated effluents or discharge requirements with regard to gross pollution parameter.

Biogas production as energy source and strategy for managing waste and climate change

The study presents technical and economic approaches of upscaled laboratory experiment using yard waste (YW) and heterogeneous slurry (HS) to produce heat and power, as a means of bridging the gap between energy production and climate change management strategies. A combination of YW:HS in ratio 2:3 with slurry obtained from a functional digester serving as inoculum was fed into the digester. These were mixed in the ratios of substrates/inoculum/water of 3.5:0.173:6.28 and theoretically upscaled for field-scale biodigesters. The modeled result shows that about 2.5 m3 gas is produced per 5-m3-sized digester over a 30-day hydraulic retention time and estimated project life of 20 years. A business model was adopted for cost recovery of the proposed waste-to-energy system and life cycle cost analysis for the production costs of the seven 5-m3 digesters. Avoided emissions of CO2 from other equivalent energy sources are 4.36 kg, 10.16 kg, 10.37 kg, and 81.32 kg, respectively, for LPG, kerosene, diesel and fuel wood/charcoal. The project is sustainable in for profit, people and planet.

Barrellite and Pillarrite: A Description and a Mode of Formation of a Novel Post-Sedimentary Twin Structures from As-Subbiyah, North of Kuwait Bay, Kuwait

I report on the occurrence of a pair of novel and related post-sedimentary structures that form in the Neogene cross-bedded red sandstones in the As-Subbiyah area, north of Kuwait Bay, Kuwait. I named them barrellite and pillarrite. Barrellite forms as vertical tubes of concentric sheaths of siltstone with partially hollow interior or intervening homogeneous and structure-less sandstone. It stands as barrels above the background sandstone. Pillarrite forms as discrete, vertical and solitary spines of homogeneous sandstone and siltstone, or inside barrellite masses from which successive siltstone sheaths were stripped. The structures range in diameter from one-centimeter poke marks to one-meter-wide barrels and hunks, and their vertical length exceeds two meters. Barrellite, pillarrite and their complex intergrowths develop near thin quartz veins and chaotic zones, and form with them complex geometrical relationships. The dual structures are genetically related and fall within the general class of tubular structures in sedimentary rocks. I consider them as a special type of sand injectites. The mode of formation of these structures is enigmatic. They develop in a geological setting that displays evidence of a widespread and vigorous oil field brine. I suggest a tentative scenario for their formation, involving flushing of the brine through hydraulic fracturing of the sedimentary succession above the Ebharah Oil Field reservoir in the As-Subbiyah area. The brine plucks mineral and rock fragments and mixes with them along its paths, producing a heterogeneous slurry. Ultimately, the slurry solidifies as barrellite and pillarrite, chaotic zones and quartz veins. The vertical nature of the structures, circular and internal concentric arrangements, as well as the homogenous lithology inside their masses mimic characteristics of flow and deposits in vertical and horizontal pipelines.

A CORRELATION FOR PRESSURE DROP PREDICTION FOR SOLID-LIQUID SLURRY FLOWS THROUGH HORIZONTAL PIPELINES

This paper has shown a correlation of pressure drop for pseudohomogeneous or mildly heterogeneous solid-liquid slurry flows through horizontal pipelines derived using a curve-fitting technique applied on exhaustive simulation data. These data are attained using a properly validated Eulerian model for multiphase flows whose applicability is confirmed for the selected range of slurry flows. The spread of geometric and working input parameters of solid-liquid slurry flows targeted during the present research work has been quite inclusive and widespread. This increases the applicability realm of the derived correlation.

Industrial Waste water Treatment and Reuses for Agricultural Purpose

In the present study, the treatment of industrial wastewater and reuses for agriculture purpose. The photocatalytic degradation of dyes like bismarck brown Y dye has been used as technique for treatment in a batch reactor under solar light in heterogeneous slurry utilizing various concentrations of ZnO as photocatalysts semiconductors. Parameters has been studied (catalyst type, catalyst concentration, pH of dye solution and dye concentration at the beginning). The results show that the best dose of ZnO is 0.80 g/l, and the optimum pH is 10. The percentage removal of chemical oxygen demand (COD) of the dye solutions was higher than that of the degradation of dye for the same conditions of catalyst. Treated wastewater reuse in agriculture is a common practice in the Mediterranean countries and there is a considerable interest in the long-term effects of treated wastewater on crops intended for human consumption. This paper studies the fundamentals of agricultural irrigation using treated wastewater and the status of industrial wastewater reuse in Iraq with studies related to the effects on soils and plants.

Effect of Operating Parameters on Degradation of Eriochrome black T Dye

Of the effect, the process parameters on photocatalytic degradation Eriochrome black T( EBT) dye has been degraded in a batch reactor under UV light in heterogeneous slurry utilizing various concentrations of two semiconductors commercial catalysts (Titanium dioxide and Zinc Oxide). The parameter has been studied (catalyst type, catalyst concentration, pH of dye solution and initial dye concentration). The results showed that the best dose of TiO2 and ZnO are 1.5 and 1 g/l respectively and the optimum pH (6 and 11) using TiO2 and ZnO respectively. Moreover, the comparative assessment of the photocatalytic efficiency was made for different photocatalytic powder. It was noticed that the best photocatalytic efficiency as ZnO > TiO2 . The investigational results were also assessed in expressions of chemical oxygen demand (COD) and color reductions to study treatment efficiency. Maximum COD removed was observed to be around 95%. The decolorization and the oxidation efficiencies could achieve 95% and 88% for ZnO and TiO2 respectively at the optimum conditions for both catalysts (30 ppm Eriochrome black T dye solution).

Numerical Investigation of Ice Slurry Flow in a Horizontal Pipe

In the last decade, phase changing material slurry (PCMS) gained much attention as a cooling medium due to its high energy storage capacity and transportability. However the flow of PCM slurry is a complex phenomenon as it affected by various parameters, i.e. fluid properties, velocity, particle size and concentration etc.. In the present work ice is used as a PCM and numerical investigation of heterogeneous slurry flow has been carried out using Eulerian KTGF model in a horizontal pipe. Firstly the present model is validated with existing experiment results available in the literature, and then model is applied to the present problem. Results show that, flow is almost homogeneous for ethanol based ice slurry with particle diameter of 0.1 mm at the velocity of 1 m/s. It is also found that ice particle distribution is more uniform at higher velocity, concentration of ice and ethanol in slurry. Results also show that ice concentration increases on the top of the pipe, and the effect of particle wall collision is more significant at higher particle diameter.

Mathematical and experimental investigation on pressure drop of heterogeneous ice slurry flow in horizontal pipes

Ice slurry as an advanced secondary refrigerant has attracted much attention due to the growing concern about energy shortage and environment protection. To promote the practical applications of ice slurry, an extensive knowledge of the pressure drop of ice slurry flow in pipes is beneficial. The available research mainly focuses on the pressure drop of ice slurry flow without considering the non-uniform distribution of ice particles within. Furthermore, the impact of the carrier fluid and ice particles on the pressure drop of ice slurry is not well documented. This investigation combined numerical, analytical and experimental methods to analyze the distributions of concentration, velocity and pressure drop in heterogeneous ice slurry flow. An analytical pressure drop model was developed based on multiphase flow dynamics to quantify the pressure drop of each phase of ice slurry flow. Experiments for laminar and turbulent ice slurry flow in horizontal pipes were used to evaluate the proposed model. The analysis revealed good agreement between the proposed model and experimental data. Moreover, the proposed analytical model is computationally efficient, which can be applied to estimate the pressure drop of ice slurry flow for most practical applications.

Distribution of Medium-to-Coarse Glass Beads in Slurry Pipe Flow: Evaluation of Measured Concentration Profiles

Concentration distribution of two fractions of glass-bead (ballotini) particles (medium size 0.44 and 0.53 mm, respectively) in flows of heterogeneous slurry was measured in a laboratory pipe of the internal diameter of 100 mm using a radiometric device. Particles in such flows are supported by both interparticle contacts and turbulent eddies and the solids load must be considered as combined load composed of both contact and suspended load. Flows tend to be partially stratified and if high concentrated (mean volumetric concentration of solids higher than approximately 20%) they exhibit a sliding bed. It appears that two most common methods to calculate concentration profiles in settling-slurry flows are not able to handle the sliding bed adequately. A comparison of the test results with the Gillies-Shook model for combined-load flows shows that the modeling approach requires further refinements. An application of the more recent Kaushal-Tomita model based on the turbulent-diffusion concept is inappropriate in high-concentrated slurries composed of medium-to-coarse grains. A simple one-dimensional model is proposed that takes conditions for an existence of a sliding bed into account and predicts a simplified concentration profile in stratified flows composed of a sliding bed and a transport layer above the bed.

Heterogeneous ice slurry flow and concentration distribution in horizontal pipes

Ice slurry is an energy-intensive solid–liquid mixture fluid which may play an important role in various cooling purposes. Knowing detailed flow information is important from the system design point of view. However, the heterogeneous ice slurry flow makes it difficult to be quantified due to the complex two phase flow characteristic. The present study applies a Mixture computational fluid dynamics (CFD) model based on different rheological behavior to characterize the heterogeneous ice slurry flow. The Mixture CFD model was firstly validated by three different experiments. Then the validated Mixture CFD model was applied to solve the ice slurry isothermal flow by considering the rheological behavior piecewise. Finally, the numerical solutions have displayed the coupled flow information, such as slurry velocity, ice particle concentration and pressure drop distribution. The results show that, the ice slurry flow distribution will appear varying degree of asymmetry under different operating conditions. The rheological behavior will be affected by the asymmetric flow distributions. When mean flow velocity is high, Thomas equation can be appropriate for describing ice slurry viscosity. While with the decreasing of mean flow velocity, the ice slurry behaves Bingham rheology. As compared with experimental pressure drop results, the relative errors of numerical computation are almost within ±15%. The Mixture CFD model is validated to be an effective model for describing heterogeneous ice slurry flow and could supply plentiful flow information.

Heterogeneous Fenton using ceria based catalysts: effects of the calcination temperature in the process efficiency

The need of more efficient solid catalysts for the heterogeneous slurry Fenton process led many investigators to research new compounds activities. Ceria based iron catalysts have proved their good performance enhancing the removal of organic compounds, reducing toxicity and improving biodegradability in the depuration of phenolic wastewaters. This work evaluates the calcination temperature (300°C, 600°C and 1000°C) during the preparation of the catalysts—co-precipitation of the precursors salts, while the same previously optimized conditions were adopted (pH 3.0, 1.0gL−1 of Fe–Ce–O 70/30 as the catalyst, [H2O2]=244mM and 120min of room temperature reaction) to treat a simulated wastewater comprising 0.1gL−1 of each of the six common phenolic acids found in Olive Mills wastewaters. The three obtained solids were characterized regarding superficial area, average pore diameter, FT-IR and XRD. Catalysts calcinated at 300°C, 600°C and 1000°C presented superficial areas of 188, 86 and 2m2/g, respectively, and their average pore diameter are 66, 87 and 151Å, correspondingly. As showed in the XRD, the increase of the calcination temperature promotes the crystallinity of the obtained solid—higher amount of prominent peaks, meaning that the catalysts have different states of valence for iron (Fe2+ or Fe3+) and ceria (Ce2+ to Ce4+), what would explain their singular behaviours during the reaction. As expected, the solids with higher superficial areas had better performances in every aspect: more COD, TOC and phenolic acids removal, pointing the lowest calcination temperature as leading to a more efficient solid to enhance hydrogen peroxidation, involving, however, more metal leaching. The higher the calcination temperature is, the more oxidized the solid will become because the calcination occurs without atmospheric control and so the oxygen contained in the air will interfere on the valence of iron ions at the solid's surface. This means that a solid calcinated at a higher temperature will have increased Fe3+ content and, as one can find in the literature, Fe2+ is more effective than Fe3+ at hydrogen peroxidation, explaining the better efficiency of the catalyst calcinated at the lowest temperature. Toxicological and biodegradability studies were still performed and showed enhancement in all cases.

A Simplified Method for the Measurement of Insoluble Solids in Pretreated Biomass Slurries

The biochemical conversion of cellulosic biomass to liquid transportation fuels includes the breakdown of biomass into its soluble, fermentable components. Pretreatment, the initial step in the conversion process, results in heterogeneous slurry comprised of both soluble and insoluble biomass components. For the purpose of tracking the progress of the conversion process, it is important to be able to accurately measure the fraction of insoluble biomass solids in the slurry. The current standard method involves separating the solids from the free liquor and then repeatedly washing the solids to remove the soluble fraction, a laborious and tedious process susceptible to operator variations. In this paper, we propose an alternative method for calculating the fraction of insoluble solids which does not require a washing step. The proposed method involves measuring the dry matter content of the whole slurry as well as the dry matter content in the isolated liquor fraction. We compared the two methods using three different pretreated biomass slurry samples and two oven-drying techniques for determining dry matter content, an important measurement for both methods. We also evaluated a large set of fraction insoluble solids data collected from previously analyzed pretreated samples. The proposed new method provided statistically equivalent results to the standard washing method when an infrared balance was used for determining dry matter content in the controlled measurement experiment. Similarly, in the large historical data set, there was no statistical difference shown between the wash and no-wash methods. The new method is offered as an alternative method for determining the fraction of insoluble solids.

Photoreactor Modeling: Applications to Advanced Oxidation Processes

A general methodology for photoreactor analysis and design based on the fundamentals of chemical reaction engineering and radiative transfer in participating media is presented. Three applications in the field of advanced oxidation processes are considered to illustrate the proposed approach: (i) a photocatalytic reactor for air purification, (ii) a homogeneous photo-Fenton solar reactor, and (iii) a heterogeneous photocatalytic slurry reactor. In the first case, the procedure is exemplified with the modeling of a multiannular photocatalytic reactor for perchloroethylene removal from contaminated air streams. A rigorous physical and mathematical model of the multiannular concentric photoreactor was developed and experimentally verified. The second approach is illustrated with the degradation of a model pollutant by the Fenton and photo-Fenton reactions in a nonconcentrating, flat-plate solar reactor. Formic acid was chosen as the model substrate. The effect of the reaction temperature on the pollutant degradation rate is analyzed. In the case of the slurry photoreactor, the intrinsic kinetics of the photocatalytic decomposition of a toxic organic compound in aqueous solution, using suspended titanium dioxide catalytic particles and ultraviolet polychromatic radiation, is studied. The kinetic parameters are evaluated for different catalyst loadings, irradiation levels and pollutant initial concentrations. By means of these illustrative examples, the need of a systematic and rigorous approach to the analysis and design of photoreactors is emphasized.

Synthesis and characterization of methyl xylan

The synthesis of methyl xylan using methyl chloride and methyl iodide as etherifying agent under varying reaction conditions was studied. The reaction of xylan with an excess of methyl chloride under pressure in the presence of 40% aqueous NaOH led to a methyl xylan with a degree of substitution (DS) of 0.94. The conversion of xylan with methyl iodide yielded DS values of about 0.5 independent of the molar ratio of methyl iodide to anhydroxylose unit homogeneously in 25% aqueous NaOH or after addition of acetone leading to a heterogeneous slurry. The DS and the distribution of the substituents were determined by means of one and two-dimensional NMR spectroscopy.

Synthesis of Polymandelide: A Degradable Polylactide Derivative with Polystyrene-like Properties

Polymandelide, an aryl analogue of polylactide, was synthesized by the ring-opening polymerization of mandelide, the cyclic dimer of mandelic acid. The poor solubility of rac-mandelide limited the synthesis of polymandelide via solution polymerization, but polymerization of mandelide at 70 °C as a heterogeneous slurry in acetonitrile yielded first-order kinetic plots and polydispersities 150 °C exhibit properties that mimic those of polystyrene. Polymandelide is a glassy amorphous polymer with a Tg of 100 °C, with rheological properties comparable to polystyrene, and thermal gravimetric analyses under nitrogen show that the polymer is stable to ∼300 °C. Racemization during polymerization precluded formation of a crystalline polymer. Degradation of polymandelide in pH 7.4 buffer at 55 °C is consistent with a bulk erosion model and, due to its high Tg, proceeds at ∼1/100 the rate of polylactide under similar conditions.

Photocatalytic treatment of wastewater from cottonseed processing: Effect of operating conditions, aerobic biodegradability and ecotoxicity

The heterogeneous and homogeneous UV-A photocatalytic treatment of an acidic waste stream originating from cottonseed processing was investigated. Several TiO 2 samples were screened in heterogeneous slurry experiments and a commercially available TiO 2 anatase (Millennium PC 500) was found to be considerably more active than the rest. The effect of key operating conditions such as effluent dilution (COD from 800 to 8000 mg/L), Millennium TiO 2 loading (from 100 to 1500 mg/L), solution pH (from 2.6 to 10) and the water matrix (presence of effluent solids and dissolved oxygen) on treatment efficiency was also studied. In general, degradation decreased with increasing effluent concentration, increasing solution pH from acidic to neutral and alkaline conditions and in the absence of oxygen serving as electron acceptor. Experiments with 500 mg/L TiO 2 for 240 min led to nearly complete mineralization at 800 mg/L initial COD but higher catalyst loadings suppressed degradation. Homogeneous experiments with 100 mg/L Fe 2+ or Fe 3+ were also performed leading to about 50% COD reduction; this increased to about 65% when H 2O 2 was added, i.e. simulating a Fenton reaction. The original, un-treated effluent was very toxic to marine bacteria Vibrio fischeri and very slowly biodegradable aerobically as assessed by shake-flask tests. Nonetheless, a 10-fold dilution (i.e. 800 mg/L COD) eliminated completely ecotoxicity and improved substantially biodegradation rates. On the other hand, photocatalytically pre-treated samples were less biodegradable than the un-treated one. Deep photocatalytic oxidation resulted in decreased ecotoxicity to V. fischeri, while moderate photocatalytic oxidation increased toxicity probably due to the formation of toxic intermediates.

Plasma-Replacement Technology of ETC-Ignition of Powder Charges in High-Velocity Launchers

The proposed plasma-replacement technology of ignition is aimed at the solution of the applied problems of high-velocity launching. Its characteristic features are the application of an additional charge consisting of a heterogeneous slurry propellant generating high-temperature two-phase combustion products and its multisite ETC-ignition achieved directly from a low-voltage energy storage. The efficiency of the proposed ignition technique is illustrated by the experimental results on the model 35-mm ETC-launcher with low-voltage energy storage

Homogeneous hydroxyethylation of cellulose in NaOH/urea aqueous solution

The 6 wt.% NaOH/4 wt.% urea aqueous solution was proved to be an aqueous non-derivatizing solvent for cellulose by 13C NMR. O-(2-hydroxyethyl)cellulose (HEC) was prepared by a totally homogeneous hydroxyethylation of cellulose using this new solvent for the first time, and the distribution of substituents within anhydroglucose units (AGU) was examined by 13C NMR. It was found that the relative reactivity of the hydroxyl groups within AGU and the new hydroxyl group was in the order C-x > C-6 > C-2 > C-3, an analogous functionalization pattern as HEC obtained by the heterogeneous slurry process. The ethylene oxide efficiency in this homogeneous etherification reaction was 20 – 30%.