Experimental investigations were carried out to adsorb toxic brilliant green dye from aqueous medium using kaolin as an adsorbent. Characterization of kaolin is done by measuring: (i) particle size ...distribution using particle size analyzer, (ii) BET surface area using BET surface analyzer, and (iii) structural analysis using X-ray diffractometer. The effects of initial dye concentration, contact time, kaolin dose, stirring speed, pH and temperature were studied for the adsorption of brilliant green in batch mode. Adsorption experiments indicate that the extent of adsorption is strongly dependent on pH of solution. Free energy of adsorption (Δ
G
0), enthalpy (Δ
H
0) and entropy (Δ
S
0) changes are calculated to know the nature of adsorption. The calculated values of Δ
G
0 at 299
K and 323
K indicate that the adsorption process is spontaneous. The estimated values of Δ
H
0 and Δ
S
0 both show the negative sign, which indicate that the adsorption process is exothermic and the dye molecules are organized on the kaolin surface in less randomly fashion than in solution. The adsorption kinetic has been described by first-order, pseudo-second-order and intra-particle-diffusion models. It was observed that the rate of dye adsorption follows pseudo-second-order model for the dye concentration range studied in the present case. Standard adsorption isotherms were used to fit the experimental equilibrium data. It was found that the adsorption of brilliant green on kaolin follows the Langmuir adsorption isotherm.
Contemporary research in ceramic composites for membrane applications targets the fabrication of stable low cost micro-filtration range membranes. This work reports the fabrication of stable low cost ...mesoporous membranes deploying subsequent formulations based on kaolin and other suitable low cost materials such as quartz, sodium carbonate, calcium carbonate, boric acid and sodium metasilicate. Incidentally, the processing temperature in this work is about 850–1000 °C instead of 1100 °C which is the usual sintering temperature for inorganic membrane fabrication. The membranes casted as circular disks (52.5 mm diameter and 4.5 mm thickness) were subjected for characterization studies using TGA, XRD, SEM analysis, to evaluate the effect of maximum sintering temperature on membrane structure, porosity and mechanical integrity. Pore size distribution, porosity, average pore size of the membrane along with permeation experiments with both water and air is carried out to study the membrane performance. The average pore size of the membrane is observed to increase from 550 nm to 810 nm when sintering temperature increases from 850 °C to 1000 °C. However, with the increase in temperature from 850 °C to 1000 °C, the membrane porosity is reduced (from 42% to 33%) and flexural strength is increased (from 3 to 8 MPa). The membrane corrosion resistance is found to be unaltered with processing temperature. Based on raw-material prices, the membrane cost is estimated to be $130/m
2. Henceforth, these low cost membranes with good membrane properties are suggested for cheaper application in chemical and biochemical processes using micro-filtration and ultra-filtration techniques.
Experimental investigations were carried out using commercially available kaolin to adsorb two different toxic cationic dyes namely crystal violet and brilliant green from aqueous medium. Kaolin was ...characterized by performing particle size distribution, BET surface area measurement and XRD analysis. The effects of initial dye concentration, contact time, adsorbent dose, stirring speed, pH, salt concentration and temperature were studied in batch mode. The extent of adsorption was strongly dependent on pH of solution. Free energy of adsorption (Δ
G
0), enthalpy (Δ
H
0) and entropy (Δ
S
0) changes were calculated. Adsorption kinetic was verified by pseudo-first-order, pseudo-second-order and intra-particle-diffusion models. The rate of adsorption of both crystal violet and brilliant green followed the pseudo-second-order model for the dye concentrations studied in the present case. The dye adsorption process was found to be external mass transfer controlled at earlier stage and intra-particle diffusion controlled at later stage. Calculated external mass transfer coefficient showed that crystal violet dye adsorbed faster than brilliant green on kaolin. Adsorption of crystal violet and brilliant green on kaolin followed the Langmuir adsorption isotherm.
This work addresses the performance and modeling of the separation of oil-in-water (o/w) emulsions using low cost ceramic membrane that was prepared from inorganic precursors such as kaolin, quartz, ...feldspar, sodium carbonate, boric acid and sodium metasilicate. Synthetic o/w emulsions constituting 125 and 250
mg/L oil concentrations were subjected to microfiltration (MF) using this membrane in batch mode of operation with varying trans-membrane pressure differentials (Δ
P) ranging from 68.95 to 275.8
kPa. The membrane exhibited 98.8% oil rejection efficiency and 5.36
×
10
−6
m
3/m
2
s permeate flux after 60
min of experimental run at 68.95
kPa trans-membrane pressure and 250
mg/L initial oil concentration. These experimental investigations confirmed the applicability of the prepared membrane in the treatment of o/w emulsions to yield permeate streams that can meet stricter environmental legislations (<10
mg/L). Subsequently, the experimental flux data has been subjected to modeling study using both conventional pore blocking models as well as back propagation-based multi-layer feed forward artificial neural network (ANN) model. Amongst several pore blocking models, the cake filtration model has been evaluated to be the best to represent the fouling phenomena. ANN has been found to perform better than the cake filtration model for the permeate flux prediction with marginally lower error values.
This work reports on microfiltration (MF) studies of mosambi juice using low cost ceramic membrane prepared from locally available inorganic precursors. Characterization of the prepared membrane was ...done by SEM analysis, porosity determination and pure water permeation experiments. The average pore diameter, total porosity and hydraulic resistance of the membrane were evaluated as 0.285
μm, 23.6% and 9.26
×
10
11
m
2/m
3, respectively. Dead-end MF experiments were performed for both centrifuged mosambi juice (CJ) and enzyme treated centrifuged mosambi juice (ETCJ). It was observed that after MF, important properties like TSS, pH, acidity and density of both CJ and ETCJ were almost unaffected. However, significant improvement in juice colour, clarity and AIS was observed. It was also observed that the clarified juice can be stored in refrigerated condition for more than 30 days without significant change in juice quality. Different membrane pore blocking models were used to analyze the observed permeate flux decline.
This work addresses the applicability of different membrane pore blocking models for the prediction of flux decline mechanisms during dead end microfiltration (MF) of stable oil-in-water (o/w) ...emulsions using relatively low-cost ceramic membranes. Circular disk type membranes (52.5 mm diameter and 4.5 mm thickness) were prepared by the paste method using locally available low-cost inorganic precursors such as kaolin, quartz, calcium carbonate, sodium carbonate, boric acid, and sodium metasilicate. Characterization of the prepared membrane was done by SEM analysis, porosity determination, and pure water permeation through the membrane. Hydraulic pore diameter, hydraulic permeability, and hydraulic resistance of the membrane was evaluated as 0.7 µm, 1.94 × 10
−6
m
3
/m
2
·s·kPa and 5.78 × 10
11
m
2
/m
3
, respectively. The prepared membrane was used for the treatment of synthetic stable o/w emulsions of 40 and 50 mg/L crude oil concentration in batch mode with varying trans-membrane pressure differentials ranging from 41.37 to 165.47 kPa. The membrane exhibited 96.97% oil rejection efficiency and 21.07 × 10
−6
m
3
/m
2
·s permeate flux after 30 min of experimental run at 165.47 kPa trans-membrane pressure for 50 mg/L oil concentration. Different pore blocking, models such as complete pore blocking, standard pore blocking, intermediate pore blocking and cake filtration were used to gain insights into the nature of membrane fouling during permeation. The observed trends for flux decline data convey that the decrease in permeate flux was initially due to intermediate pore blocking (during 1 to 10 minutes of experimental run) followed with cake filtration (during 10 to 30 minutes of experimental run). Based on retail prices of the inorganic precursors, the membrane cost was estimated to be 130 $/m
2
. Finally, preliminary process economic studies for a single stage membrane plant were performed for the application of the prepared membrane in industrial scale treatment of o/w emulsions. A process economics study inferred that the annualized cost of the membrane plant would be 0.098 $/m
3
feed for treating 100 m
3
/day feed with oil concentration of 50 mg/L.
In this paper, we develop a new class of models for a compact star with anisotropic stresses inside the matter distribution. By assuming a linear equation of state for the anisotropic matter ...composition of the star we solve the Einstein field equations. In our approach, for the interior solutions we use a particular form of the an satz for the metric function grr. The exterior solution is assumed as the Schwarzschild metric and is joined with the interior metric obtained across the boundary of the star. These matching of the metrices along with the condition of the vanishing radial pressure at the boundary lead us to determine the model parameters. The physical acceptability of the solutions has verified by making use of the current estimated data available from the pulsar 4U1608−52. Thereafter, assuming anisotropy due to tidal effects we calculate the Love numbers from our model and compare the results with the observed compact stars, viz. KS1731−260, 4U1608−52, 4U1724−207, 4U1820−30, SAXJ1748.9−2021 and EXO1745−268. The overall situation confirms physical viability of the proposed approach, which can shed new light on the interior of the compact relativistic objects.
•Investigation of a compact star with anisotropic stresses.•We assume a linear equation of state to solve the Einstein field equations.•Love numbers are calculated from the presented model.•We have compared the results with the observed compact stars.•Solutions provide a physical viability of the proposed approach.
In this work, experimental investigations were carried out for the identification of optimal membrane morphological parameters (pore size distribution, average pore size and porosity) during ...microfiltration (MF) of mosambi juice using low cost ceramic membranes. Four different low cost ceramic membranes with different pore diameters (
d
m) and porosities (
ɛ) were subjected to MF studies to evaluate the effect of
d
m and
ɛ on permeation characteristics (permeate flux and juice quality) of centrifuged mosambi juice (CJ) and enzyme treated centrifuged mosambi juice (ETCJ). Subsequently, a convenient factor namely effective permeable area factor (
ɛ
m
d
m
2) was evaluated to provide greater insights in the fouling phenomena. Various physio-chemical properties such as colour, clarity, pH, citric acid content, density, total soluble solid (TSS) and alcohol insoluble solids (AIS) were measured for both feed and permeate juice samples to evaluate the effect of
ɛ
m
d
m
2 on juice quality. Typical permeate fluxes were observed to vary from 5.78
×
10
−6 to 13.45
×
10
−6
m
3/m
2
s for CJ and 14.07
×
10
−6 to 60.64
×
10
−6
m
3/m
2
s for ETCJ at 82.7
kPa (Δ
P) for different membranes whose
ɛ
m
d
m
2 varied from 0.249 to 0.783
μm
2. Among different membrane pore blocking models, flux decline by cake filtration was found to be the best fitted model. The cake filtration model constant (
k
c) was found to vary with Δ
P and
ɛ
m
d
m
2 and was empirically correlated. Phenomenological models were proposed to illustrate the dependency of total hydraulic resistance of membrane on
ɛ
m
d
m
2, Δ
P and time (
t). Based on experimental as well as theoretical investigations, membranes with
ɛ
m
d
m
2 up to 0.443
μm
2 for CJ and 0.294
μm
2 for ETCJ and a Δ
P of 82.7
kPa were recommended for MF of mosambi juice.
Experimental investigations are carried out to adsorb toxic crystal violet dye from aqueous medium using kaolin as an adsorbent. Characterization of kaolin is done by measuring
The effects of initial ...dye concentration, contact time, kaolin dose, stirring speed, pH, and temperature are studied for the adsorption of crystal violet in batch mode. Adsorption experiments indicate that the extent of adsorption is strongly dependent on the pH of the solution. Free energy of adsorption (ΔG
o
), enthalpy (ΔH
o
), and entropy (ΔS
o
) changes are calculated to know the nature of adsorption. The calculated values of ΔG
o
are −4.11 and −4.48 kJ/mol at 295 K and 323 K, respectively, for 20 mg/L of dye concentration, which indicates that the adsorption process is spontaneous. The estimated values of ΔH
o
and ΔS
o
show the negative and positive sign, respectively, which indicate that the adsorption process is exothermic and the dye molecules are organized on the kaolin surface in more random fashion than in solution. The adsorption kinetic has been described by pseudo first order, pseudo second order and intra-particle diffusion models. It is observed that the rate of dye adsorption follows pseudo second order model for the dye concentration range studied in the present case. Standard adsorption isotherms are used to fit the experimental equilibrium data. It is found that the adsorption of crystal violet on kaolin follows the Langmuir adsorption isotherm.
Comprehensive results on the production of unidentified charged particles, π±, K±, K$_S^0$, K*(892)0, $p, \bar{p}, ϕ$(1020), Λ, Λ, Ξ-, Ξ+, Ω-, and $\bar{Ω}^+$ hadrons in proton-proton ...(pp) collisions at $ \sqrt{s}$=7 TeV at midrapidity (|y|<0.5) as a function of charged-particle multiplicity density are presented. In order to avoid autocorrelation biases, the actual transverse momentum (pT) spectra of the particles under study and the event activity are measured in different rapidity windows. In the highest multiplicity class, the charged-particle density reaches about 3.5 times the value measured in inelastic collisions. While the yield of protons normalized to pions remains approximately constant as a function of multiplicity, the corresponding ratios of strange hadrons to pions show a significant enhancement that increases with increasing strangeness content. Furthermore, all identified particle-to-pion ratios are shown to depend solely on charged-particle multiplicity density, regardless of system type and collision energy. The evolution of the spectral shapes with multiplicity and hadron mass shows patterns that are similar to those observed in p-Pb and Pb-Pb collisions at Large Hadron Collider energies. The obtained pT distributions and yields are compared to expectations from QCD-based pp event generators as well as to predictions from thermal and hydrodynamic models. These comparisons indicate that traces of a collective, equilibrated system are already present in high-multiplicity pp collisions.
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