Vikas Kumar Sangal

Optimization of structural and operational variables for the energy efficiency of a divided wall distillation column

Abstract In the present work, the optimization of different structural and process parameters of a divided wall column (DWC) for the energy efficiency has been presented. The optimal design and operation of divided wall distillation columns involve a number of variables and is a non-linear problem. Rigorous simulation of a DWC was carried out using Multifrac model of ASPEN Plus software. Box–Behnken design (BBD) under response surface methodology (RSM) was used for the optimization of the parameters and to evaluate the effects of these parameters and their interactions on the energy efficiency of a DWC. The process variables were found to have significant effect on the energy efficiency of a DWC as compared to the effect of structural variables, and the predictions from the BBD optimization agree well with the results of the rigorous simulation.

Electrocoagulation of Soluble Oil Wastewater: Parametric and Kinetic Study

Soluble oils (cutting oils) in aqueous solution are used extensively in the engineering and metal working industries, as coolants, metal forming fluids, and/or lubricants. Hysol-X is a general-purpose cutting oil used in 1–10% concentration in aqueous solution. This paper investigates demulsification of soluble-oil-water emulsion using electrocoagulation with aluminum electrodes. It examines the current efficiency and the pH variation of the system due to electrocoagulation and the effect of pH of the oil-water emulsion, current density, and temperature on the demulsification process. A simple first order kinetics fits the experimental data at a constant value of current density. The optimum pH and current density were found to be 6.50 and 138.8 A/m2, respectively. Apparent electrode current efficiency was found to be 115.5%. Temperature has significant effect on emulsion stability and solution pH. At a lower temperature of 20°C or a higher temperature of 60°C, the turbidity (or oil) removal is found to be very high. More than 99% oil separation is achieved in 3 h at 20°C. The residual aluminum concentration in the treated water at an initial pH 6.5 is found to be 0.001 mg/l, well below the statutory discharge standard value.

Modeling and evaluation of electro-oxidation of dye wastewater using artificial neural networks

Treatment of CBSOL LE red wool dye containing wastewater by an electro-oxidation (EO) method was investigated using Ti/RuO2 electrode. The performance of the EO system was evaluated in terms of % dye degradation (Y1) and % colour removal (Y2) along with important operating cost parameters such as energy consumed (Y3) at three EO process parameters: pH, current (i) and time (t). ANNs were applied for the modeling of the EO process, and optimization was performed by using multi response optimization by desirability function approach of Central composite Design (CCD) with stimulated data obtained from ANNs. Modeling for the treatment of CBSOL LE red wool dye wastewater by the EO process was done successfully by ANNs, and optimization by CCD vividly underscores interactions between variables and their effects for the degradation of CBSOL LE red wool dye by the EO process. At the optimum conditions, the actual % dye degradation (Y1), % color removal (Y2) and energy consumed (Y3) were 89.87%, 96.71%, 2.029 Wh respectively. The predictions agree well with the experimental results. It was found that both the mechanisms of EO treatment i.e. direct oxidation and indirect oxidation are responsible for the dye degradation/color removal. Color was found to be nearly completely removed, whereas 10.13% of dye is present in the treated wastewater.

Decolorization and degradation of Reactive Black 5 dye by photocatalysis: modeling, optimization and kinetic study

AbstractPhotocatalytic treatment of Reactive Black 5 dye wastewater was carried out using suspension of commercially available TiO2 catalyst under ultraviolet irradiation in a shallow pond reactor. An artificial neural network (ANN) model was developed to predict the behavior of the process. Six operational parameters (TiO2 dose, initial dye concentration, pH of the dye solution, area to volume ratio, UV light intensity, and time) were employed as input and decolorization and degradation efficiencies were employed as output of the network. The outcomes have been validated experimentally indicating that the ANN provided reasonable predictive performance. The parameteric optimization was done, using multiresponse optimization with desirability function approach, to simultaneously maximize the decolorization and degradation efficiency. Optimization by Box–Behnken design effectively copes with interaction between optimizing variables and its prediction agreed well with the results of ANN model and experimenta...

Divided wall distillation column: rationalization of degree of freedom analysis

The present work attempts to rationalize the degrees of freedom analysis of a divided wall distillation column for steady-state simulation using detailed mathematical model, which contains the MESHD equations (conventional MESH equation plus the pressure drop equation). In a divided wall distillation column, pressure difference plays an important role in deciding vapour and liquid flow rates across trays in the divided section. It is observed that for a given divided wall distillation column or Petlyuk column operating under steady state conditions with known feed and condenser pressure, the degrees of freedom is four. This is one higher than that for a conventional distillation column with three product streams (distillate, bottoms and the intermediate product). If this extra degrees of freedom is used to specify liquid split, then no extra degrees of freedom is left to specify vapour split ratio.

Synthesis, characterization and anticancer activities of metal ions Fe and Cu doped and co-doped TiO2

TiO2 nanoparticles have been doped and co-doped with two metal ions (Fe and Cu) via the wet impregnation method. The doped and co-doped TiO2 have been characterized by standard analytical techniques like XRD, Raman spectra, FTIR, UV-Vis DRS, FESEM, and TEM. Powder XRD technique reveals that the modified catalyst majorly contains an anatase phase with the existence of metal ions in the lattice of TiO2. Raman and UV-Vis absorption spectra of the doped and co-doped catalyst show a λmax shift towards the longer wavelength region with an increase in metal ion concentration from 1 to 2%. FTIR patterns show the stretching and vibration patterns of the hydroxyl radicals present in the nanoparticles. FESEM images reveal that the average particle size of the modified TiO2 lies between 18 and 24 nm due to the asymmetric shape of nano crystallite TiO2. TEM images suggest that the doping and co-doping of metal ions do not leave any change in the shape of the nanoparticles. Furthermore, anti-cancerous activities of TiO2 nanoparticles and Fe, Cu doped and co-doped particles have been studied, revealing the toxicity of Cu ions doped TiO2 on cervical cancer cell line.

Electrocatalytic oxidative treatment of real textile wastewater in continuous reactor: Degradation pathway and disposability study

Electrocatalytic treatment of real textile wastewater was investigated in continuous electrochemical reactor using dimensionally stable Ti/RuO2 anode. Effects of various parameters such as: elapsed time, current, pH, retention time on the COD removal, color removal and specific energy consumed were evaluated. Central Composite Design under RSM was used for experimental design, data analysis, optimization, interaction analysis between the various electrochemical parameters and steady state time analysis. GC-MS and UV spectrophotometric analysis of the untreated and treated wastewater were conducted to identify the oxidized and transformed/degraded compounds during the oxidation process, and a suitable degradation mechanism was proposed. Treated wastewater may contain toxic chlorinated compounds due to mediated oxidation by various hydrolyzed chlorine species. Therefore, disposability of treated wastewater was assessed by conducting toxicity bioassay test. The optimal set of operating parameters were found to be elapsed time = 124 min, current = 1.37 A, pH = 5.54 and retention time = 157.6 min to simultaneously achieve COD removal, color removal and specific energy consumed as 86.22%, 94.74% and 0.012 kW h, respectively. GC-MS analysis showed presence of chlorinated compounds in the treated wastewater. The toxicity bioassay test resulted acute toxicity with 100% mortality rate within one minute and one hour exposure with untreated and treated textile wastewater, respectively.

Radiotracer investigation and modeling of an activated sludge system in a pulp and paper industry

A radiotracer investigation was carried out in an activated sludge process (ASP) system of an effluent treatment plant in a pulp and paper industry. The system consists of an aeration tank and a secondary clarifier connected in series. The primary objective of the investigation was to measure mean hydraulic retention times (MHRTs) of wastewater and investigate the hydraulic performance of the ASP. Residence time distributions (RTD) of the wastewater were measured in an aeration tank and a secondary clarifier of the system using Iodine-131 as a radiotracer. The measured RTD data was treated and MHRTs were estimated. No bypassing was found to exist in the aeration tank and the secondary clarifier. However, the dead volume in the aeration tank and the secondary clarifier was found and estimated to be 2.34% and 4.6%, respectively. The treated curves were further simulated using suitable hydraulically representative mathematical models and detailed flow patterns in the aeration tank and the secondary clarifier were deciphered.

Optimization of photocatalytic process parameters for the degradation of acrylonitrile using Box Behnken Design

AbstractThe present study involves the photocatalytic degradation of aqueous solution of acrylonitrile (ACN) which was carried out in a batch reactor under UV light. The degradation efficiency was evaluated with ZnO as a photocatalyst and hydrogen peroxide as an oxidant for a period of 5 h. The variables examined in this study included ZnO dose (0.5–3.0 g/L), pH (2–12), and H2O2 concentration (2.5–10 m mol/L). The rate of degradation was studied in terms of changes in concentration of the pollutant using spectrophotometry. The optimal values of operational parameters leading to degradation of ACN were obtained using Box Behnken design (BBD) under response surface methodology (RSM). The optimum conditions were found to be ZnO dose of 1.48 g/L; pH 7.0 and hydrogen peroxide (H2O2) concentration of 4.22 m mol/L. Under optimum condition, the degradation efficiency of ACN was found to be 89.6%. Optimization of photocatalytic process parameters for the degradation of ACN by BBD under RSM effectively copes with i...

Catalyst-coated cement beads for the degradation and mineralization of fungicide carbendazim using laboratory and pilot-scale reactor: catalyst stability analysis

ABSTRACT The fixed-bed photocatalytic degradation of fungicide carbendazim using catalyst-coated spherical cement beads has been investigated. Thirty beads with optimum size 13 mm along with 0.3 gL−1 H2O2 with an initial concentration of carbendazim of 10 mgL−1 were the optimized conditions for better degradation. The reduction in COD and total organic carbon along with the generation of nitrite and nitrate ions under the optimized conditions confirms the complete mineralization of compound. The suggested degradation pathway for carbendazim has also been proposed as intermediates formed during photodegradation were analyzed through gas chromatography–mass spectrometry. The coated cement beads were found to be durable even after 30 cycles as confirmed by scanning electron microscopy and energy dispersive spectroscopy analysis. Scale-up trails have also been carried out in a solar-baffled fixed-bed reactor for the degradation of pollutant to seek the commercial viability of the technique. GRAPHICAL ABSTRACT