The interaction second virial coefficients, B12, and PVTx behavior for the binary systems consisting of N2, CO2, CH4, C2H6, C3H8, and normal C4H10 are estimated by means of the Deiters equation of state (EoS). In this way a new combining rule based on the modified Lorentz–Berthelot combining rule is proposed for this EoS. The binary interaction parameters for these combining rules are calculated by fitting the expression for the interaction second virial coefficient derived from the Deiters EoS to the experimental cross virial coefficient data. The calculated B12 values from the optimized binary interaction parameters and Deiters EoS are in good agreement with experimental data. Also a van der Waals type mixing rule with the two binary interaction parameters kij and lij obtained from the experimental B12 values is presented for the Deiters equation of state, which is able to predict the volumetric properties of the above mixtures to a good degree of accuracy in the specified temperature and pressure range. Also it has been shown that the Deiters EoS has higher accuracy relative to the Peng–Robinson EoS for the prediction of the volumetric properties of the mixtures studied in this work.
An experimental study of the effect of gas sparger geometry and agitator location on gas distribution in agitated systems is presented. The results have shown that varying the impeller position modified the size of low void fraction zone. The optimum impeller position for achieving a small low voidage zone without changing the flow pattern has been identified. It was found that impeller positions below or above the optimal location have a negative effect on gas dispersion while the sparger geometry did not affect significantly the overall gas distribution. Low void fraction zone could be detected by a void sensor even if not visually observed.
NaCl crystals were precipitated on a liquid–liquid interface and control of the NaCl crystal shape could be realised. The interface between NaCl aqueous solution and 1-butanol, which show phase separation for small solubility of water and 1-butanol into each other, was used as a crystallization field. Asymmetric NaCl crystals could be created on the interface for changing of NaCl concentration due to mutual diffusion between two solvents. The particle size distribution could be controlled by changing the contact time between the NaCl solution and 1-butanol. The growth rate of NaCl crystals was varied with the concentration of the NaCl solution.
This study has explored a new source of carbonaceous materials, i.e., sunflower seed husk for the adsorption separation process. Activated carbons were produced from sunflower seed husk using phosphoric acid activation in nitrogen. The properties of activated carbons, i.e., bulk density, ash content, iodine number, surface area and surface functional groups were measured together with copper and chromium adsorption activities. The carbon adsorbed 0.75 mmol Cu2+/g carbon and 0.37 mmol Cr6+/g carbon. The Langmuir model best fitted the copper ion adsorption data, while the Freundlich model best fitted the chromium ion adsorption data. Copper and chromium uptake was directly correlated with the number of groups titrable with the base. The results indicated that the acid-activated sunflower seed husk-based carbons were effective metal ion adsorbents and could potentially replace typical coal-based activated carbons in the treatment of metal contaminated wastewater.
To gain a better understanding of the dynamic behavior of continuous emulsion polymerization, the authors developed a simple stochastic model which considers the competitive interaction between polymerization reaction and aggregation of latex particles. The numerical results were then compared with the experimental data from continuous emulsion polymerization of vinyl acetate carried out under various operating conditions. The numerical and experimental results showed satisfactory agreement. It was found that the dynamic behavior of particle size distribution is affected by latex particle aggregation and the feed flow rate.
A novel superstructure-based MINLP formulation is proposed for the synthesis of cooling water networks with intermediate mains. The proposed mathematical model considers the generic problem confronted in the design of a recirculating cooling-water system, including stretching the cooler network design and setting the operation constraints. Besides the original design items, this research probes into how the number of intermediate cooling-water mains influences the performance of a recirculating cooling-water system. We also study how the conditional direct connections between cooling units can decrease the consumption of the recirculating cooling-water with a little sacrifice of pipeline complexity. Typical representative examples are presented to demonstrate the viability of proposed superstructure-based MINLP formulation. Supported by the results of computer analysis, the network superstructure and its design scheme can effectively accomplish the goal of unraveling the design problem of the recirculating cooling-water system with intermediate cooling-water mains, and proffering the optimal structure in designing the recirculating cooling-water systems.
The combined use of an equilibrium model and artificial neural network (NN) regressions has been investigated for modelling biomass gasification. The benefits of this approach are to improve the accuracy of equilibrium calculations, and to prevent the NN model from learning mass and energy balances, thereby minimising experimental data requirements. A complete stoichiometry is formulated, and corresponding reaction temperature difference parameters computed under the constraint of the non-equilibrium distribution of gasification products determined by mass balance data reconciliation. The NN regressions relate temperature differences to fuel composition and gasifier operating conditions. The application of Bootstrap and Bayesian regularisation validation algorithms has been investigated to prevent the NN from overfitting the data, and for estimating prediction intervals (PI). Given the prior knowledge available from experimental data, PI become of particular interest for determining whether a regression is indeed required, or whether it is reasonable to consider a given reaction temperature difference independent of composition and operation variables. The results of a preliminary investigation, illustrated with atmospheric air gasification fluidised bed reactor data, indicate that for the reactions relating to the equilibrium of major gas phase species (the water gas shift reaction and ammonia formation from nitrogen and hydrogen) the temperature difference could be constant. Furthermore, the shift reaction might be at equilibrium. Char, light hydrocarbon, and tar formation reaction temperature differences appear to be more strongly correlated to changes in operating conditions.
We report the dispersibility of nano-TiO2 with fine ceramic media beads, zirconia, silica, alumina and titania of less than 1 mm in size. The pastes were water-based with polymeric dispersal by means of the rocking apparatus. Dispersibility of the pastes was evaluated in progress using a measurement of the pastes’ particle sizes. The results showed that smaller beads produced nano-TiO2 disperse effectively and independently of the bead material. Plasma melted 0.03 mm zirconia beads presenting advantages over sintered beads against the contamination of zirconium in dispersal. Observation of each film’s inner structure clarified that a highly mesoporous condition was obtainable from these good dispersive pastes.
An adsorption heat pump (AHP) is proposed to expand the available heat sources and to increase cooling power. The main objective of this research is to carry out the conceptual study of operation range in points of adsorption equilibria and experimental study of desorption and adsorption processes by silica gel–water AHP which is composed of a mechanical booster pump (MBP) and an adsorber of packed bed. This effect is confirmed experimentally. In these experimental ranges, the amount of pump power is effective to increase cooling power. Therefore, it is confirmed that the range of temperature, which is able to use as a heat source, is expanded and cooling power is increased directly by pump power.
Self-organized TiO2 nanotube-layers were formed by the electrochemical anodization of Ti in an HF electrolyte. The nanotube layers were then treated at different temperatures (300–600°C) in the air. Platinum was doped on the TiO2 nanotube layer by e-beam sputtering. The samples were characterized by EDX, BET, XPS, SEM, XRD and photoelectrochemistry. The results clearly showed the successful Pt-doping of the TiO2 nanotubes. The photocatalytic evolution of H2 due to the decomposition of water in the alkaline solution was investigated using the Pt–TiO2 nanotubes as a photocatalyst and iodide ions in the form of KI as a redox mediator. The results showed that the Pt–TiO2 nanotube photocatalyst generated H2 successfully.
A tannin gel was prepared from condensed tannin (wattle tannin), which is a ubiquitous and inexpensive natural material extracted from the leaves or barks of plants. The tannin gel has the ability to adsorb and reduce the metal ions with a redox potential higher than that of the tannin gel. The selective recovery of Au from a mixed solution of various precious metal ions (Au, Pd, Pt, and Rh) was performed using such features of the tannin gel. The predominant species of each precious metal ion are AuCl4–, PdCl42–, PtCl62–, and RhCl52– at pH 1.0 and pCl 1.0. The redox potential of the AuCl4–/Au couple is much higher than that of the tannin gel, while the other precious metals such as the PtCl62–/PtCl42– couple, PdCl42–/Pd couple, and RhCl52–/Rh couple have redox potentials lower than that of the tannin gel. Under the conditions of pH 1.0 and pCl 1.0, the entire amount of Au in the solution was adsorbed perfectly by the tannin gel, while the other precious metals were hardly adsorbed. The adsorbed Au was reduced to metallic Au on the tannin gel. Thus the selective adsorption and reduction of Au could be achieved by controlling the predominant ions of each precious metal ion in the solution.
The accumulation of calcium onto granular activated carbon (GAC) used for landfill leachate treatment and its effects on the adsorption of 2,4-DCP were studied. A GAC column was installed after the coagulation-sedimentation process of a treatment plant for landfill leachate from a municipal waste landfill site. Major inorganic material accumulated onto the GAC used for landfill leachate treatment was calcium. The accumulation of calcium onto GAC was leveled off in 8 weeks’ operation at about 7 mg g–1, which was much smaller than that reported in drinking water treatment irrespective of the higher concentrations of DOC and calcium in water. The main species of calcium accumulated onto the GAC used for leachate treatment was calcium associated with DOC. Different calcium species in GAC may give different effects on the adsorption capacity of GAC. The accumulation of calcium onto GAC did not decrease the adsorption capacity for 2,4-DCP.