•Faster decolorization of AB-14 dye by AO and EC and follow pseudo-first order kinetic.•Faster and similar decolorization by EC and AO due to the generation of strong oxidant OH in the bulk.•Current ...density (j), Initial dye conc. (Co), NaCl conc. (CN), and pH affect the oxidation efficiency.•Synergy between coagulation and oxidation by OH and active chlorine species.
In this study, a laboratory scale for the treatment of a recalcitrant and toxic synthetic wastewater containing diazo dye, acid brown 14 (AB-14) has been comparatively performed by two electro-catalytic treatment processes, namely anodic oxidation (AO) and electrocoagulation (EC) using a new batch electrochemical cell. Additionally, the influence of several operating parameters such as; current density (j), initial dye concentration (Co), NaCl concentration (CN), and pH on the color removal efficiency and chemical oxygen demand (COD) are evaluated. The powerful capability of the AO and EC of AB-14 which related to the mechanistic reaction pathway is shown. The poor degradation is ascribed to higher Co and pH, while the enhancement of j and CN is responsible for better degradation of AB-14 dye. The results indicate that the EC is more effective than AO under the same operational condition. A kinetic model is developed for evaluation of the pseudo-first-order-rate constant (kapp) as a function of various operational parameters. The results emphasize the high efficiency of AO and EC and the clean processes which are hopeful alternative for the treatment of the large volume wastewater of the textile industry.
This study explores the possibility of using electrocoagulation to remove phenol from oil refinery waste effluent using a cell with horizontally oriented aluminum cathode and a horizontal aluminum ...screen anode. The removal of phenol was investigated in terms of various parameters namely: pH, operating time, current density, initial phenol concentration and addition of NaCl. Removal of phenol during electrocoagulation was due to combined effect of sweep coagulation and adsorption. The results showed that, at high current density and solution pH 7, remarkable removal of 97% of phenol after 2
h can be achieved. The rate of electrocoagulation was observed to increase as the phenol concentration decreases; the maximum removal rate was attained at 30
mg
L
−1 phenol concentration. For a given current density using an array of closely packed Al screens as anode was found to be more effective than single screen anode, the percentage phenol removal was found to increase with increasing the number of screens per array. After 2
h of electrocoagulation, 94.5% of initial phenol concentration was removed from the petroleum refinery wastewater. Energy consumption and aluminum Electrode consumption were calculated per gram of phenol removed. The present study shows that, electrocoagulation of phenol using aluminum electrodes is a promising process.
The effective removal of heavy metals from aqueous wastes is among the most important issues for many industrialized countries. Removal of lead (II) and copper (II) from aqueous solutions were ...studied using pomegranate peel (raw), activated carbon prepared from pomegranate peel (AC
1) and activated carbon prepared from chemically treated pomegranate peel (AC
2 and AC
3). Batch adsorption experiments were performed as a function of pH, contact time, solute concentration and adsorbent dose. The optimum pH required for maximum adsorption were found to be 5.6 and 5.8, for lead and copper respectively. The experimental equilibrium adsorption data are tested for the Langmuir, Freundlich and Temkin equations. Results indicate the following order to fit the isotherms: Langmuir > Temkin > Freundlich in case of lead ions and Freundlich > Temkin > Langmuir in case of copper ions. Adsorption kinetics data were modeled using the pseudo-first and pseudo-second order, Elvoich equations and intraparticle diffusion models. The results indicate that the second-order model best describes adsorption kinetic data.
The present work represents a comparative study for removing acid green dye 50 by anodic oxidation and electrocoagulation using a new batch self gas stirred electrochemical cell. The effect of ...operating parameters such as current density, initial dye concentration, NaCl concentration and pH on the efficiency of colour removal has been examined. The chemical oxygen demand (COD) reduction under suitable operating conditions was also calculated and found to be reduced by 68% and 87% in case of electrochemical oxidation and electrocoagulation methods, respectively. The results indicate that electrocoagulation is more economic than anodic oxidation, energy consumption ranged from 2.8 to 12.8
kWh/kg dye removed in case of electrocoagulation while in case of anodic oxidation it ranged from 3.31 to 16.97
kWh/kg dye removed. Although the mechanisms of electrocoagulation and anodic oxidation are different, results show that the first-order rate equation provides the best correlation for the decolourization rate of acid green 50 by the two methods.
Abstract Photocatalytic degradation of several harmful organic compounds has been presented as a potential approach to detoxify water in recent decades. Trypan Blue (TB) is an acidic azo dye used to ...distinguish live cells from dead ones and it's classified as a carcinogenic dye. In this study, silver phosphate (Ag 3 PO 4 ) nanoparticles and novel Ag 3 PO 4 /graphene/SiO 2 nanocomposite have been successfully prepared via simple precipitation method. Afterward, their physical properties, chemical composition, and morphology have been characterized using SEM, EDS, TEM, SAED, BET, XRD, FTIR and UV–VIS spectroscopy. The specific surface area of Ag 3 PO 4 and Ag 3 PO 4 /G/SiO 2 nanocomposite were reported to be 1.53 and 84.97 m 2 /g, respectively. The band gap energy of Ag 3 PO 4 and Ag 3 PO 4 /G/SiO 2 nanocomposite was measured to be 2.4 and 2.307 eV, respectively. Photocatalytic degradation of Trypan blue (TB) was studied at different parameters such as pH, catalyst dosage, initial concentration, and contact time. The results showed that, at initial dye concentration of 20 ppm, pH = 2, and using 0.03 g of Ag 3 PO 4 /G/SiO 2 as a photocatalyst, the degradation percent of TB dye in the aqueous solution was 98.7% within 10 min of light exposure. Several adsorption isotherms such as Langmuir, Freundlich, and Temkin adsorption isotherms have been tested in addition to the photocatalytic degradation kinetics. Both catalysts were found to follow the Langmuir isotherm model and pseudo-second-order kinetic model. Finally, the possible photocatalytic performance mechanism of Ag 3 PO 4 /G/SiO 2 was proposed.
Recovery of copper from synthetic waste solution using cementation technique in a new agitated vessel employing multirotating aluminum cylinders impeller was investigated. Parameters studied are ...cylinder diameter, rotation speed, initial copper ion concentrations, and effect of surfactants. Solution analysis and scanning electron microscopy were employed to investigate the kinetic and mechanism of the process. The rate of recovery was found to be at its maximum value at the operating conditions of 350 rpm rotation speed, 5000 ppm initial CuSO
4
concentration, and 1.2 cm cylinder diameter. All data were correlated by the dimensionless equation:
Sh
=
1.16
Sc
0.33
Re
0.63
d
c
L
0.54
,
with an average deviation of ±8.5 pct and a standard deviation of 5.88 pct. Presence of nonylphenol ethoxylate surfactant in the solution decreased the rate of recovery by an amount ranging from 2.94 to 38.57 pct depending on the operating conditions. The present geometry gave higher rates of recovery compared to both the single rotating cylinder and rotating disc reactor.
Electrochemical treatment of organic pollutants is a promising treatment technique for substances which are resistant to biodegradation. In this study an electrochemical treatment based on the ...principle of anodic oxidation was used to treat paper mill effluent from Rakta's Pulp and Paper Company where rice straw is used to produce paper pulp. Experiments were carried out in a cylindrical agitated vessel lined with lead sheet as anode while a concentric cylindrical stainless steel sheet screen was placed as a cathode. The effect of current density, pH, NaCl concentration, impeller rotational speed and temperature on the rate of color and COD removal was studied. The results showed that the use of electrochemical technique reduces the COD from an average value of 5500 to 160. The percentage color removal ranged from 53% to 100% depending on the operating conditions. Energy consumption calculation shows that energy consumption ranges from 4 to 29
kWh/m
3 of effluent depending on the operating conditions. The experimental results proved that the electrochemical oxidation is a powerful tool for treating paper mill effluents where rice straw is used as a raw material.
Rates of mass transfer in a spiral coil were measured by a technique involving the diffusion-controlled dissolution of copper in acidified dichromate. The variables studied were solution velocity, ...spiral tube pitch, and physical properties of the solution. The data were correlated by the equation
For a given set of conditions, the mass transfer coefficient predicted from the above equation was found to be much higher than that of the straight tube. Comparison of the ratio between the mass transfer coefficient and pressure drop for spiral tubes and straight tubes has revealed that
for spiral tubes is much higher than that of a straight tube under the present range of conditions. The possibility of using the above equation in predicting the rate of diffusion-controlled corrosion and the corrosion allowance needed to design a spiral tube heat exchanger was noted. Other possible applications in heterogeneous reactor design and membrane processes are reported.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
► The reactor used in the study was a rotating cylinder packed with cation exchange resin. ► The experimental data were analyzed using different isotherms. ► The equilibrium data fit well in the ...Langmuir isotherm. ► The experimental data were analyzed using four sorption kinetic models. ► Results show that the Elovich equation provides the best correlation for the biosorption process.
The present study is concerned with the mass transfer and kinetics study of zinc ions removal from aqueous solution using a cation exchange resin packed in a rotating cylindrical basket reactor. The effect of various experimental parameters on the rate of zinc ion removal, such as initial zinc ion concentration, packed bed rotation speed and temperature has been investigated. In addition to find a suitable equilibrium isotherm and kinetic model for the zinc ion removal in a batch reactor. The experimental isotherm data were analyzed using the Langmuir, Freundlich and D–R equations. The equilibrium data fit well in the Langmuir isotherm. The experimental data were analyzed using four sorption kinetic models, pseudo-first and second-order equations, the Elovich and the intraparticle diffusion model equation, to determine the best fit equation for the biosorption of zinc ions onto purolite C-100 MH resin. Results show that the Elovich equation provides the best correlation for the biosorption process.
This paper deals with the electrocoagulation of real wastewater produced from a car wash station using a new cell design featuring a horizontal spiral anode placed above a horizontal disc cathode. ...The study dealt with the chemical oxygen demand (COD) reduction and turbidity removal using electrodes in a batch mode. Various operating parameters such as current density, initial pH, NaCl concentration, temperature, and electrode material were examined to optimize the performance of the process. Also, characterization of sludge formed during electrocoagulation was carried out. The results indicated that the COD reduction and turbidity removal increase with increasing the current density and NaCl concentration; pH from 7 to 8 was found to be optimum for treating the wastewater. Temperature was found to have an insignificant effect on the process. Aluminum was superior to iron as a sacrificial electrode material in treating car wash wastewater. Energy consumption based on COD reduction ranged from 2.32 to 15.1 kWh/kg COD removed depending on the operating conditions. Finally, the sludge produced during electrocoagulation using aluminum electrodes was characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analysis.
