Chemical Engineering

This paper contains the results of a new experimental study of the temperature effect on density and ultrasonic velocity for peanut (Arachis hypogaea), canola (Brassica napus L., Brassica rapa L. and Brassica juncea) and rosa mosqueta (Rosa affinis rubiginosa L.) oils. The Halvorsen’s model (HM), and Collision Factor Theory (CFT) were selected for prediction of these properties, attending to ease of use and range of application. An accurate response was observed, despite of the use of molecular group contribution procedures for estimation of theoretical critical points and the complex nature of the studied fluids.

In this study coal fly ash (CFA) which is the waste product of coal fired power plant is used as an adsorbent for adsorption of phenol from aqueous solution in packed bed column. The effect of bed height (7.5, 13.5, 27.5 cm), effect of flow rate (0.375, 0.75 and 1.0 ml/min) and initial phenol concentration (70.0, 292.7, 651.2, 1039.9 mgL-1) on the adsorption were studied by assessing the breakthrough curve. Thomas and Yoon-Nelson models were used to evaluate the column performance. The result shows that with increase in flow rate, break point time decreases while the values of maximum adsorption capacity (q0) decreased and the Thomas constant (KTh) increased. As the bed height and initial concentration increases, break point time increases with bed height but decreases with initial concentration but q0 increased while KTh decreased. The maximum adsorption capacity was found to be 5.90 mg/g at 1.0 ml/min flow rate and 27.5 cm bed height with phenol concentration of 1039.9 mg/L. Key words: Coal fly ash, Phenol, packed bed column, adsorption, Thomas and Yoon Nelson model.

The failures of the bituminous pavements are not only due to increase in traffic but also due to extreme climatic conditions prevailing in the country. The addition of polymers to bitumen can improve the quality of binders and enhance the properties of binders used in the road construction. Bitumen ageing is one of the principal factors causing the deterioration of asphalt pavements due to the prolonged exposure to air and environmental conditions. Short-term ageing occurs when binder is mixed with aggregates in a mixing facility. Long-term ageing occurs after pavement construction and is generally due to environmental exposure and loading. The properties of bitumen mainly depend on the age of bitumen. Therefore there is a need to study the properties of modified bitumen before and after ageing. In this paper the effect of Aging on the physical properties of SBS (Styrene Butadiene Styrene) modified bitumen is discussed.

The hexavalent chromium present in waste water has adverse affect on aquatic life and humans. Various methods are available for the removal of hexavalent chromium includes chemical precipitation, ion exchange, reduction, electrochemical precipitation, solvent extraction, membrane separation, evaporation, foam separation and biosorption. Among these, biosorption is one of the low cost separation technique for the removal of chromium using agricultural waste as adsorbents which are cheap and readily available and also has the advantage of practical replacement to conventional processes. The kinetic models and adsorption isotherms for the efficient removal of hexavalent chromium are presented from various sources. The present review elaborate the findings of hexavalent chromium removal with the maximum metal uptake, adsorption parameters using agricultural wastes as adsorbents

Power generation efficiency of a DMFC depends on the concentration of methanol solution, hence analysis on the development of methanol concentration sensor is getting importance. Measurement of methanol concentration using various techniques namely MEMS, Capacitive type, Dielectric constant and piezoelectric crystal are critically analyzed in this paper. Based on the specific requirement, a particular type of methanol concentration sensor is utilized for the defined power output of DMFC.

The present study investigates the oxidative-conversion of propane-butane (C3–C4) fraction to methanol via a proposed vapor–gas system: C3–C4 + O2 + h?/HN?3 ? 2??3?? + C2H4 + C3H6. Experiments were performed by feeding propane-butane fraction, oxygen, and nitric-acid into a photo-chemical reactor under mild conditions at a temperature of 100oC, an atmospheric pressure (P = 1 atm.), and under the influence of electromagnetic radiation using visible-light excitation at a wavelength ? = 420 nm, and at reaction-times (tr) between 2 – 120 minutes. The major oxidation-products are methanol, ethylene, and propylene. From this approach, methanol with 90 % selectivity can be achieved at a single-pass C3–C4 conversion level of 10 %. Quantum-chemical calculations for the oxidation reaction of C3–C4 by hydroxyl radical (via HN?3 photo-dissociation) were performed using the density functional theory (DFT) method at the B3LYP/6-311++G(3df,3pd) level, and the calculation-results are broadly consistent with the experimental data. In a strict sense, the applied technique herein for the oxidation of C3–C4 to methanol, and the valuable semi-products (alkene), as well as to enhances the regeneration of nitric-acid, apparently finds physico-chemical justification.

Direct Methanol Fuel Cells (DMFC) offers one of the most promising alternatives to the replacement of fossil fuels. However effective the design of the fuel cell may be, it cannot perform effectively without proper modelling and simulation. The importance and the need for the modelling of a DMFC are discussed in detail. The modeling of the key components such as the gas diffusion layer, MEA, flow distribution, catalyst thickness which contributes to the performance of the fuel cell are discussed.

Heavy metal accumulation in waste water could affect aquatic life, human health and overall ecosystem adversely. Therefore, in recent years much emphasis has been given for the use of agricultural waste as low cost adsorbents for the removal of metallic contaminants from waste water. In this paper, the studies on removal of Cu (II) by adsorption on custard apple peel powder as adsorbent have been investigated in a batch type experiments. The agitation time, the adsorbent size, adsorbent dosage, initial copper concentration, and the effect of solution pH are studied. The Freundlich model for Cu (II) adsorption onto Custard apple peel powder is proved to be the best fit followed by Langmuir model and Tempkin model based on high regression coefficient R2 value. The adsorption kinetic behavior is best described by second order. The maximum percentage removal of metal efficiency is found to be 93.97 %. The results obtained in this study illustrate that custard apple peel powder is expected to be an effective and economically viable adsorbent for Cu (II) removal from industrial waste water.

Design of proportional integral and derivative (PID) controllers for unstable SOPTDZ (Second Order Plus Time Delay with a Zero) system with a negative/positive zero is difficult. If zero is positive, it shows an inverse response. A simple method is proposed to design proportional integral and derivative controllers for such systems. The proposed controller is applied to the various unstable transfer function models of exothermic CSTR, an isothermal CSTR carrying out an autocatalytic reaction and crystallizer. Simulation results on linear model equations of exothermic CSTR, an isothermal CSTR carrying out an autocatalytic reaction and crystallizer are given to show the effectiveness of the proposed PID controller. The performance of proposed controller in terms of integral square error (ISE), integral absolute error (IAE) and integral time weighted absolute error (ITAE) is compared with the literature reported data.

The present paper involves the application of chemical and photochemical homogeneous advanced oxidation processes on the decolourization of textile effluent and Methyl Orange (MO) Dye. The decolourization efficiency of various oxidants such as hydrogen peroxide (H₂O₂), fenton reagent i.e. hydrogen peroxide and hydrated ferrous sulphate (H₂O₂/Fe²⁺), sodium hypochlorite (NaClO), UV/H₂O₂/Fe²⁺, Solar/H₂O₂/Fe²⁺, UV/NaClO and Solar/NaClO has been investigated. The effect of process parameters viz., oxidant dose, pH, concentration of dye and source of light (UV/Solar) for decolourization and COD reduction of dye effluent and MO has been studied. The decolourization efficiency was estimated from residual concentration spectrophotometrically. The experimental results show that the maximum decolourisation (more than 95 %) and COD reduction (40 %) of effluent occurred using combined Solar/NaClO (20 mg/L) system at pH 6 within 20 minutes. The decolourization efficiency of MO dye with H₂O₂ or UV alone was found to be negligible but more than 95% efficiency could be achieved either with UV/H₂O₂/Fe²⁺ (450 mg/L /150 mg/L) at pH 2 or Solar/NaClO (120 mg/L) at pH 6 within 30 minutes.