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Methyl decanoate is used as a surrogate fuel. The surrogate fuels are structurally similar to actual biodiesel. We synthesized methyl decanoate in a small batch reactor by esterification reaction u...

The conversion of sucrose to a highly concentrated commercial syrup by immobilized invertase by combining the processes of adsorption and cross-linking using Duolite A-568 as the carrier was studied. Central Composite Design (CCD) was used to assess the effect of glutaraldehyde concentration and cross-linking reaction time on immobilized enzyme activity throughout the hydrolysis of sucrose in a batch reactor. Cross-linking optimization allowed us to find the optimum conditions for activity with a glutaraldehyde concentration of 0.6 g · L−1 and a cross-linking time of 6 h. The temperature and pH that maximized the activity of the immobilized biocatalyst in the cross-linking process were 50°C and 4.0, respectively. Cross-linking allows the biocatalyst to be active at higher temperatures and lower pH. High-sucrose conversions to invert sugar using a continuous fixed-bed reactor were obtained. The immobilized biocatalyst also demonstrated greater thermal stability at low temperatures.

The aim of this paper is to present an alternative to conventional biodiesel production by taking advantage of the flow patterns formed in micro-reactors. Biodiesel production was carried out 15 times faster in a tubular micro-reactor (TMR) than a well-mixed batch reactor (BR), achieving conversions up to ∼99% with 4 min of residence time. The experimental results were analyzed using dimensionless numbers and computational fluid dynamics (CFD) simulations. The CFD results showed that under the conditions used in the present study, the slug flow pattern can be expected, and this could explain the high conversion (>90%) reached in the TMR without using high methanol-oil molar ratios. The internal movement (auto-mixing) in the slug enhanced the mass transfer. Moreover, CFD simulations showed that at low conversion (

In this work, a mechanistic model was developed on the basis of population balance equations for butadiene emulsion polymerization and validated with experimental data in a batch reactor. A combination of finite difference and weighted essentially nonconciliatory (WENO) schemes was used as a precise technique for the discretization of the population balance equations. The obtained values during the evolution of conversion and the average particle diameter values were in good agreement with the measured results for different surfactant concentrations. However, the simulated particle-size distributions (PSDs) were much narrower than the experimental PSDs. Therefore, to match the experimental PSDs, a stochastic term was included in the zero–one model. The effect of surfactant concentration, which is an important factor with a direct impact on the dispersion coefficient, was also investigated and confirmed with experimental results.

Using zeolites as catalysts of coal pyrolysis for production of valuable chemical compounds such as aromatics is being widely investigated and has shown promising results. In this study, pure faujasite-type Y zeolite crystals were successfully synthesized by a direct hydrothermal method with sodium silicate solution and colloidal silica as the silicon sources, without any seeding gel. A novel approach was adopted to directly synthesize zeolites impregnated with nickel oxide. Moreover, a batch reactor was designed to increase the silica/alumina ratio (SAR) of the zeolites by dealumination process without causing significant damage to the zeolite structure. The various analysis methods were employed to characterize the parent and modified zeolites, and the fabricated zeolites were applied in coal pyrolysis experiments. The results are presented in order to show the catalytic performance of the faujasite-type Y zeolites for application in coal pyrolysis process.

In this research, the decolorization of Acid Blue 25 (AB25) was investigated at experimental conditions, using process in a stirred batch reactor. It was discovered that the removal efficiency of AB25 is sensitive to the operational parameters such as initial concentration of , temperature and initial pH of the solutions. Natural initial pH and room temperature were found to be the optimum conditions for the process. Optimum oxidant concentration required for the removal of AB25 was reduced in high temperatures. In this study, the maximum color removal efficiency of AB25 was found to be more than 95% at 60°C in optimum conditions for 3 mM peroxydisulfate concentration. The electrical energy per order (E EO) values was also calculated for decolorization of AB25 solution. The results showed that E EO can be reduced by applying a desired peroxydisulfate concentration. The value of process quantum yield was calculated in this experiment. The kinetics of the process were investigated and rate constant, activat...

Oil palm frond (OPF) fiber, a lignocellulosic waste from the palm oil industry, contains high cellulose and hemicellulose content, thus it is a potential feedstock for simple sugars production. This paper describes the two-stage hydrolysis process focusing on the use of low-temperature dilute acid hydrolysis to convert the hemicellulose in OPF fiber to simple sugars (xylose, arabinose, and glucose). The objective of the present study was to evaluate the effect of operating conditions of dilute sulfuric acid hydrolysis undertaken in a 1 L self-built batch reactor on xylose production from OPF fiber. The reaction conditions were temperatures (100–140°C), acid concentrations (2–6%), and reaction times (30–240 min). The mass ratio of solid/liquid was kept at 1:30. Analysis of the three main sugars glucose, xylose, and arabinose were determined using high-pressure liquid chromatography. The optimum reaction temperature, reaction time, and acid concentration were found to be 120°C, 120 min, and 2% acid, respect...

The aim of the present work is to demonstrate the technical feasibility of treating high-strength distillery wastewater in an electrochemical flow reactor and to predict the result using an artificial neural network (ANN) model. The experiments were conducted using oxide coated on expanded titanium (Ti/Ru0.3Ti0.7O2) as anode and stainless steel as cathode in a batch reactor with electrolytic recirculation. Pollutant degradation was measured as chemical oxygen demand (COD) for various operating parameters such as effluent flow rate, current density, and supporting electrolyte concentration. Experiments were conducted for various flow rates, supporting electrolyte concentrations, and current density. An ANN was used for modeling the experimental results. The model was developed using a feed-forward back-propagation network with different layers and neurons. It can be concluded that the network configuration of 3-3-3-1 simulation gives the best result in predicting the experimental results with a high correl...

Galacturonic acid is a monosaccharide obtained by pectin hydrolysis and a suitable substrate to produce bioethanol by fermentation. This article focuses on quantification of citrus pectin hydrolysis to galacturonic acid and provides new, reliable kinetic parameters for the Michaelis-Menten equation when the well-known commercial Pectinex Ultra SP-L is employed as enzyme. They are: r max = 1.10 g/(L min), K m = 10.42 g/L, and K IGA = 10.05 g/L, as obtained with a great accuracy by a nonlinear regression method and confirmed by the three classical linearization procedures (Lineweaver-Burk, Langmuir, and Eadie-Hofstee). The quantification of product inhibition has been achieved, with its inclusion in the rate equation. A batch reactor model yields perfect agreement between predictions and experiments, even under conditions different from those on which the parameters had been determined by regression.

In this study, an initiator (Fe2+) and a scavenger (CO3 2−) were used at different concentrations in a batch reactor to investigate the reaction mechanism of ozonation of a model azo dye, namely Acid Red-151 (AR-151). Also, the effect of a nonionic surfactant known as a major pollutant in many industrial wastewaters, namely polyethylene glycol (PEG), was observed on the degradation rate of AR-151. The experimental parameters and their ranges were: pH (2.5–10), initiator (0.8–50 mg/L of Fe2+), surfactant (10–200 mg/L of PEG), and scavenger (10–500 mg/L of CO3 2−); the initial concentration of the azo dye was kept constant at 20 mg/L in all the experiments. Results showed that decomposition of ozone was enhanced with increasing pH and increasing initiator (Fe2+) concentration at a scavenger concentration of 100 mg/L, when there is no dye in the medium. A scavenger concentration of 100 mg/L CO3 2− was not sufficient to terminate the chain reactions of ozone decomposition. It was concluded that the dominant m...

Catalytic activities of synthesized solid base catalysts (alumina loaded with solution of different potassium compounds such as KI, KF, K2CO3, and KNO3 with the loading amount of 35 wt.%) were tested for the transesterification reaction of canola oil with methanol and ethanol in a batch reactor in a temperature range of 25–60°C and different feed ratios of methanol/oil between 6:1 and 18:1. Synthesized KF/Al2O3 solid base catalyst showed the highest activity in the transesterification of canola oil with methanol and gave much stabler methyl ester content during the reaction with the highest yield of 99.6% at the end of the eight-hour reaction time at 60°C, with a methanol/oil ratio of 15:1 and a catalyst amount of 3 wt.%. Formation of K2O phase and the formation of the surface Al-O-K groups by salt-support interactions were observed during the synthesis of the catalysts. Methanol was found to be much more reactive than ethanol in the transesterification reaction.

In the present study, glucose and galactose inhibition effects for β-galactosidase hydrolyzing lactose recovered from whey were investigated. The experiments were carried out in 250 mL of 25 mM phosphate buffer solution containing 1, 1.5, 2, 4, and 6% (w/v) lactose recovered from whey by using a commercial β-galactosidase produced from Kluyveromyces marxianus lactis at a constant temperature of 37°C, pH 6.5, and enzyme concentration of 1 mL/L, in a batch reactor system. The amounts of glucose and galactose added to the reaction solution were 6.25, 12.5, and 25 g/L. A second-order kinetic expression effectively simulated the data of residual lactose concentration with respect to processing time for each experimental condition examined. The Lineweaver-Burk plots showed that the inhibition effects of glucose and galactose were uncompetitive. The inhibition constants (Ki) obtained for glucose and galactose (10.32 g/L and 13.03 g/L, respectively) showed that the glucose was the most effective inhibitor for β-g...

In the present work, the effects of impeller speed and viscosity on the enzymatic hydrolysis of whey lactose and enzyme inactivation were studied. The experiments were carried out in 250 mL of 25 mM phosphate buffer solution containing 50 g/L whey lactose by using a commercial β-galactosidase produced from Kluyveromyces marxianus in a batch reactor system. The degree of lactose hydrolysis (%) and residual enzyme activity (%) was investigated versus impeller speeds from 100 to 600 rpm and viscosities from 1.005 to 13.43 cp for 30 minutes of processing time. The mathematical models depending on these process parameters were derived using the experimental data of residual lactose concentration and residual β-galactosidase activity. The predicted models have been confirmed with the experimental results.

In the present study, the photocatalytic degradation of 2,4,6-trichlorophenol (2,4,6-TCP) was carried out in a batch reactor under UV light in aqueous solution for 5 h using titania P-25 (surface area 50 m2/g) as a photocatalyst and sodium hypochlorite as an oxidant. Variables studied include catalyst dose (0.25–1.25 g/L), pH (2–6), and concentration of the oxidant (3.06 × 10−6M–15.3 × 10−6M). The rate of degradation was studied in terms of changes in concentration of the pollutant and reduction in chemical oxygen demand. The optimal values of operational parameters leading to 2,4,6-TCP abatement were obtained by using response surface methodology. The percent degradation and COD reduction of 2,4,6-TCP was found to increase with increases in the catalyst dose up to the dose of 1.1 g/L, pH in the range of 4–4.5, and oxidant concentration of 9.95 × 10−6M.

A study of high-temperature, concentrated-acid hydrolysis kinetics was undertaken for pretreated pine utilizing a corotating twin-screw extruder reactor. Five different acid concentrations were prepared ranging from 5 to 30 wt.% acid. These solutions were subjected to high-temperature acid hydrolysis at 110°, 120°, and 130°C using a custom-fabricated zirconium batch reactor. A number of nonlinear and linear regression analyses were undertaken so that the concentration of less resistant cellulose, resistant cellulose, glucose, and decomposition products could be obtained as a function of time, temperature, and acid concentration. Application of the kinetic rate constants obtained from the static batch reactor hydrolysis studies demonstrates that more than 50% of the theoretical glucose available in the pine sawdust can be obtained in roughly 25 minutes and 41% of the theoretical glucose available can be achieved in as little as 3 minutes. Further analysis highlights the importance of the pretreatment techn...

Liquid-phase esterification reaction of 1-propanol with pentanoic acid to give propyl pentanoate over Amberlyst 15 has been studied. The reaction carried out in a batch reactor was found to be independent of mass transfer effects in the temperature range of 323.15–363.15 K. The reaction is highly temperature sensitive. Increase in 1-propanol concentration has an enhancing effect on the conversion, whereas water acts as an inhibitor. As alcohol–acid mixtures behave nonideally, kinetic analysis has been performed using UNIFAC liquid-phase activities of pentanoic acid, 1-propanol, propyl ester, and water. Observed kinetics is best represented by Eley–Rideal mechanism. Surface reaction was observed to be a rate-limiting step.

During reaction crystallization of europium oxalate in a semi-batch reactor, a monotonical increase in the mean particle size and corresponding reduction in the total particle population were observed due to particle agglomeration occurring simultaneously with particle nucleation and growth. However, since particle agglomeration was achieved via particle aggregation and molecular growth, the mean particle size and total particle population in the product suspension were significantly influenced by the crystallization conditions of the feed concentration, agitation speed, and feeding time. A higher feed concentration and feeding time resulted in a larger mean particle size and smaller total particle population due to the higher supersaturation and longer holding time in the reactor. Meanwhile, agitation was found to exhibit a rather complicated influence on particle agglomeration because particle collision and a turbulent fluid shear were both promoted at the same time. In the semi-batch reactor, ...

The performance of generalized predictive control (GPC) was examined and compared with conventional control applied to the temperature of as free radical solution polymerization of styrene in a jacketed batch reactor. Optimal conditions were obtained at different initiator concentrations by applying Lagrange's multiplier to the relevant polymerization reactor. The use of the polynomial ARIMAX model related with reactor temperature and heat input was emphasized. Model parameters were determined using the Kalman algorithm. A pseudo random binary sequence (PRBS) signal was employed in order to operate the system. The GPC control method was based on the ARIMAX model. The performance criteria of GPC in evaluating the temperature control results were the required monomer conversion and molecular weight.

This work demonstrates important factor influencing the reusability of the phase transfer catalyst in the third liquid phase in addition to the role of the possible loss of catalyst due to the dissolution of the catalyst into the aqueous and organic phases. When the catalyst might react with the byproducts, in addition to reacting with the organic substrate and aqueous nucleophile, it would lose its catalytic activity. The substitution reaction between the organic substrate and an aqueous nucleophile (sodium phenolate) with tetra-n-butylammonium bromide as a phase-transfer catalyst was employed as a model reaction and was performed in a batch reactor. Three organic substrates, including allyl bromide, n-butyl bromide, and ethyl 2-bromoisobutyrate, were tested. Each of the third liquid phases formed in these tri-liquid-phase catalytic systems was utilized three times to observe the change in the activity of the catalyst. The catalyst in the third liquid phase can be reused without any loss of its catalytic...

In this study, the treatment of highly polluted synthetic phenolic wastewater in a tubular continuous electrochemical reactor was modeled and solved by the finite difference method. The reaction conditions were previously optimized with batch reactor experiments, and the synthetic wastewater containing 443 mg/L and 3063 mg/L initial phenol concentrations was treated in the runs at 25°C with 120 g/L electrolyte concentration. For the model solution, the column was divided into 10 nodes in z-direction and 9 nodes in r-direction with the intervals j z=3.5 cm, j r=0.5 cm, and j t=10 s and 1.2 min for 443 mg/L and 3063 mg/L phenol feed concentrations, respectively. The results of the model solution correlated with the experimental data fairly well, which could be useful in the design and scale up of tubular continuous electrochemical reactors for phenol removal.

Reactions of carbonaceous materials (activated carbon, graphite, and lignin) with carbon dioxide were carried out at 973 K using alkali metal carbonates (m.p. 891∼1164 K) and eutectic mixtures of these compounds (m.p. 669∼787 K) as catalysts. The reaction occurred when the carbonate catalysts were physically mixed with carbonaceous materials and the melting points of the catalysts were lower than the reaction temperature. However, the reaction did not proceed with physically mixed catalysts when the melting points of the catalysts were higher than the reaction temperature. Repeated use of the molten catalyst was also studied to investigate the possibility of continuous gasification of carbonaceous materials. After the activated carbon (or lignin) was consumed in a batch reactor, the same amount was added in the reactor containing the catalyst and the reaction started again. It was found that the eutectic molten catalyst could be reused without any loss of its catalytic activity by repeating this operation.

The application of Non-Linear Generalized Predictive Control (NLGPC) to the free radical solution polymerization of styrene in a jacketed batch reactor has been realized. The dynamic behavior of polymerization reactor is modelled and simulated for control purposes. The optimal temperature policies for minimum time, desired conversion and molecular chain length were obtained at different initiator concentrations by applying the optimal control theory which is based on the Hamiltonian principle. The polynomial Nonlinear auto Regressive Integrated Moving Average with external input (NARIMAX) model is used to relate the reactor temperature with heat input for nonlinear control algorithm. The linear (ARIMAX) and nonlinear (NARIMAX) models are utilized in the GPC algorithm for comparison. A Pseudo Random Binary Sequence (PRBS) signal was employed to operate the system. The model parameters are evaluated by using Levenberg Marquart Method. The NLGPC, Linear Generalized Predictive Control (LGPC) and standard PID ...

Based on on-line pH measurement, a comparative study between batch and semibalch reactors performance has been carried out in a glass-jacketed reactor of 51 provided with the measuring, data acquiring and controlling system. The reaction system chosen was an acid-base reaction, the concentrations of the species in the reactor were obtained simply by measuring the pH of reaction solution. Based on the conductivity profiles of the solution at different temperatures, the kinetic equation of this acid-base reaction was established. The thermal behaviors of batch reactor were investigated by heating and cooling water in the reactor. The dynamic behavior of batch reaction could be described by a set of differential equations resulting from the mass and energy balance of the reaction mixture, the energy balance of the jacket wall and the circulating fluid inside the jacket. This model has been validated with experimental results, and could be applied to the complex control situations.

The effects of turbulent mixing on barium sulfate precipitation in an imperfectly mixed double jet semi batch reactor were investigated experimentally and theoretically. When two feed solutions in separate streams were fed into the semi batch reactor, the precipitation was significantly altered by the impeller speed and the feeding time. Generally, in the range of low impeller speed (below 400 rpm), the suspension was segregated vertically in the reactor and the average particle size increased with increasing impeller speed. However, in the range of high impeller speed (above 400 rpm) the suspension was homogeneously dispersed in the reactor, but the trend of the turbulent mixing effect on the precipitation was opposite to that in range of the low impeller speed. The precipitation in the semi batch reactor was controlled by particle mass transfer and micromixing of the feed streams, both of which were promoted by increasing the impeller speed. At low impeller speed the influence of the mass trans...

The reaction kinetics between COS and aqueous solutions of some heterocyclic amines have been studied at 303 K. The reaction of COS with l,4-Diazabicyclo[2.2.2]oclane (DAB) and 1,2-Dimethylimidazole (DMI) has been investigated in an intensely stirred batch reactor; the reaction between COS and aqueous solutions of l,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) has been studied by means of the stirred cell technique. The reaction of COS with aqueous DMI and DAB was found to be extremely slow and the observed reaction order in the amine concentration was about 0·8. The overall reaction rate for the reaction of COS with aqueous DBU solutions was rather high, whereas the observed reaction order in the DBU concentration was found to be about 1·7.

The performances of semi-batch and batch reactors are compared using a variety of conditions. Differential equations for mass and thermal balances are presented for the general semi-batch process and integrated solutions for particular cases are obtained for the final temperature rise in the adiabatic case. Reduced variables and dimensionless parametric groups were employed to produce differential equations of more general applicability than hitherto. For adiabatic reactions, numerical solutions of the appropriate differential equations should be self-consistent with integrated, thermodynamic results. To illustrate the further considerations required in the application of the general schema, an exothermic parallel-consecutive reaction occuring in the liquid phase was considered: A+B→C, A+C→D and comparison is made to the related batch process with equivalent stoichiometric amounts. The reaction scheme was studied under isothermal and nonisothermal conditions; in the latter case, both adiabatically and with heat transfer. This example is of practical significance and poses an interesting problem in selectivity involving a non-trival energy balance. Numerical computation predicts that the performance of a semi-batch reactor matches a batch reactor when a solution of A is added to a solution of B using either an isothermal or an adiabatic operation; but with heat transfer facility, a purer intermediate product C may be obtained from a semi-batch reactor. When a solution of B is added to one of A, or when an initially empty tank is being filled with reaction mixture, the reaction path deviates from the batch reactor case and further reaction of C is favoured. Usually, semi-batch operation time exceeds that for batch processing and is a self-limiting criterion of performance. These disparate elements of performance are combined in a figure-of-merit to facilitate comparison of the overall productive outcome

Recently two powerful control algorithms, namely, dynamic matrix control (DMC) and extended self-tuning regulator (ESTR), have been advocated for the design of robust industrial controllers. The present paper demonstrates the application of DMC and ESTR algorithms to a bulk methyl methacrylate batch polymerization reactor operating under strong diffusional limitations of termination and propagation reactions. A realistic mathematical model is employed to simulate the strong nonlinear, time-varying dynamics of the polymerization process. The general control objective is to maintain the monomer conversion and number-average molecular weight along some desired state trajectories despite the presence of process disturbances in the total initiator concentration. It is shown that both controllers can satisfactorily control the monomer conversion and number-average molecular weight by manipulating the polymerization temperature. The similarities and the main operating features of the two controllers are...

A general Liapunov function for a homogeneous CSTR is formally developed from available Liapunov functions which guarantee the global asymptotic stability of steady states associated with the separate mechanisms (flow mixing and chemical reaction) which compete in a CSTR. The Liapunov functions for the asymptotic systems (mixing tank and batch reactor) are combined via a one parameter correlation form to provide a one parameter family of Liapunov functions for the general CSTR. The single parameter allows for convenient optimization of regions of asymptotic stability surrounding CSTR steady states.

Langmuir-Hinshelwood-Hougen-Watson rate expressions are developed for the hydroprocessing of quinoline, naphthalene and dibenzothiophene based on batch reactor data at 350°C and at 500 psig. Based on competitive adsorption, the kinetics are extended to binary mixtures of quinoline/naphtha-lene and quinoline/dibenzothiophene. In doing so, the differences in hydrogenation and hydro-genolysis sites are taken into consideration. In all cases, the agreement between the predicted and experimental results are good

Using a stochastic approach, a fresh analysis has been provided to resolve the possible causes of the existing conflicts in the reactivity ratio estimation in copolymerization systems. The analysis provides some new clues regarding the inadequacy of a transient system (batch reactor) and suggests the use of a steady state operation (CSTR) as a more reliable method.

A globally stable adaptive predictive control system (APCS) is evaluated by application to a simulated PVC batch reactor. The reactor is run under APCS control with the objective of either temperature setpoint tracking or constant reaction rate. The batch nature of this system makes it possible to learn about the physical problem from successive runs. This knowledge is incorporated into the control strategy to improve the performance of the reactor. The problem of excessive manipulation of the control variable has been recognized and resolved by using control weighting. Performance of the adaptive technique is compared with previous results using self-tuning and PID control of the same reactor. APCS provides good, robust control despite the nonlinear dynamics of the system.

The chlorination of paracresol is used in an experimental study of selectivity in gas-liquid contactors. Experiments in a batch reactor show the influence on selectivity of the dimensionless numbers presented in Part I and involving competition between mass transfer and chemical reaction together with the hydrodynamics. The extension of open reactor model presented in Part 1 to the batch reactor permits a comparison between theory and experiments and shows a good agreement

A bench-scale batch reactor was used to study the polymerization of butadiene with nickel(II) stearate Et2AlCl catalyst. In particular, the effects of moisture on polymerization were investigated. The initiation reaction is sensitive to temperature. At 0°C an induction period was observed, but at room temperature initiation can be assumed instantaneous. Water enhances catalytic reactivity, however at water concentrations greater than 10 mmol/L, termination reactions become significant. Maximum conversion is obtained in the 6 to 15 mmol/L range of water. The determining step for the molecular weight of polymer is the chain transfer to monomer. At low H2O concentration the molecular weight increases with water concentration, however it becomes independent of water concentration at high moisture content. With the help of statistical analysis of the experimental data, a two-active-species model was developed to describe the kinetics of the system and to explain certain polymerization characteristics.

In wet limestone flue gas desulfurization (FGD), elevated fly ash loadings can initiate the formation of liquid phase aluminum/fluoride (A1F n ) complexes which inhibit limestone dissolution, causing depressed slurry pH and reduced SO2 removal. This phenomenon was examined in a bench-scale pilot FGD scrubber system, and in batch reactor experiments, under conditions similar to those in full-scale utility FGD systems. It was shown that leachability of aluminum from fly ash is a critical factor, and depends on pH, fluoride concentration, and solid material properties. Reductions in limestone dissolution rate of more than an order of magnitude were measured at soluble aluminum concentrations as low as l0ppm. The implications for full-scale FGD systems reinforce the importance of maintaining efficient particulate removal upstream of the FGD scrubber.

The effect of imperfect mixing in a single batch reactor was studied using a two-tank system model with internal recycle and unequal volumes. The double-valued relationship between the reactant in each tank of the model for the A → B biochemical/chemical reversible and irreversible reactions was used to analyze mixing patterns in poorly mixed stirred-tank reactors.

The flotation behavior of fine coal particles was investigated using batch reactor. Important factors affecting solid recovery such as coal type, pH, and surfactant types were studied. Effect of inorganic salts such as NaNO3, Ca(NO3)2 and AJ(NO3)3 on surfactant performance was also studied. Elec-trokinetic and solid recovery measurements yielded consistent results delineating the mechanism of solid removal.