Abstract: In this study, production possibilities of hydrogen and/or methane via SCWG from black grape residues have been investigated. For this aim, grape residues which remain as a byproduct of the wine making process have been used. Since utilization from grape residues is limited due to the high moisture content, supercritical water gasification is the most convenient method. The effect of the gasification temperature and type of catalyst on supercritical water gasification have been investigated. Gasification experiments were performed in a batch autoclave at four different temperatures 300, 400, 500 and 600°C. K2CO3 and Trona (NaHCO3.Na2CO3·2H2O) were used as catalyst. Real biomass types of black grape residues have been successfully gasified and the product gas (hydrogen, methane, carbon dioxide, carbon monoxide and a small amount of ethane and ethylene) were identified by using gas chromatography. A TOC analyzer was used to determine total organic carbon (TOC) content of aqueous phase. The amounts of carboxylic acids, aldehydes, ketones, furfurals and phenols present in the aqueous solutions were analyzed by high performance liquid chromatography. When the temperature increased from 300°C to 600°C, mol% of H2 in gas products increased. The presence of catalysts improves the hydrogen yield. Trona showed gasification activity to be similar to that of K2CO3. It may be concluded that the use of Trona instead of commercially produced catalysts, can be preferably used in the gasification of biomass in supercritical water.
Abstract: An artificial neural network (ANN) model is
presented for the prediction of kinematic viscosity of binary mixtures
of poly (ethylene glycol) (PEG) in water as a function of temperature,
number-average molecular weight and mass fraction. Kinematic
viscosities data of aqueous solutions for PEG (0.55419×10-6 –
9.875×10-6 m2/s) were obtained from the literature for a wide range
of temperatures (277.15 - 338.15 K), number-average molecular
weight (200 -10000), and mass fraction (0.0 – 1.0). A three layer
feed-forward artificial neural network was employed. This model
predicts the kinematic viscosity with a mean square error (MSE) of
0.281 and the coefficient of determination (R2) of 0.983. The results
show that the kinematic viscosity of binary mixture of PEG in water
could be successfully predicted using an artificial neural network
model.
Abstract: The effects of equilibrium time, solution pH, and
sorption temperature of cationic methylene blue (MB) adsorption on nanoporous metallosilicoaluminophosphate ZnAPSO-34 was studied
using a batch equilibration method. UV–VIS spectroscopy was used
to obtain the adsorption isotherms at 20° C. The optimum period for
adsorption was 300 min. However, MB removal increased from
81,82 % to 94,81 %. The equilibrium adsorption data was analyzed
by using Langmuir, Freundlich and Temkin isotherm models.
Langmuir isotherm was found to be the better-fitting model and the process followed pseudo second–order kinetics. The results showed
that ZnAPSO-34 could be employed as an effective material and could be an attractive alternative for the removal of dyes and colors
from aqueous solutions.
Abstract: The adsorption of simulated aqueous solution containing textile remazol reactive dye, namely Red 3BS by palm shell activated carbon (PSAC) as adsorbent was carried out using Response Surface Methodology (RSM). A Box-Behnken design in three most important operating variables; initial dye concentration, dosage of adsorbent and speed of impeller was employed for experimental design and optimization of results. The significance of independent variables and their interactions were tested by means of the analysis of variance (ANOVA) with 95% confidence limits. Model indicated that with the increasing of dosage and speed give the result of removal up to 90% with the capacity uptake more than 7 mg/g. High regression coefficient between the variables and the response (R-Sq = 93.9%) showed of good evaluation of experimental data by polynomial regression model.
Abstract: Adsorption of Toluidine blue dye from aqueous solutions onto Neem Leaf Powder (NLP) has been investigated. The surface characterization of this natural material was examined by Particle size analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy and X-Ray Diffraction (XRD). The effects of process parameters such as initial concentration, pH, temperature and contact duration on the adsorption capacities have been evaluated, in which pH has been found to be most effective parameter among all. The data were analyzed using the Langmuir and Freundlich for explaining the equilibrium characteristics of adsorption. And kinetic models like pseudo first- order, second-order model and Elovich equation were utilized to describe the kinetic data. The experimental data were well fitted with Langmuir adsorption isotherm model and pseudo second order kinetic model. The thermodynamic parameters, such as Free energy of adsorption (AG"), enthalpy change (AH') and entropy change (AS°) were also determined and evaluated.
Abstract: Many non-conventional adsorbent have been studied
as economic alternative to commercial activated carbon and mostly
agricultural waste have been introduced such as rubber leaf powder
and hazelnut shell. Microwave Incinerated Rice Husk Ash
(MIRHA), produced from the rice husk is one of the low-cost
materials that were used as adsorbent of heavy metal. The aim of
this research was to study the feasibility of using MIRHA500 and
MIRHA800 as adsorbent for the removal of Cu(II) metal ions from
aqueous solutions by the batch studies. The adsorption of Cu(II) into
MIRHA500 and MIRH800 favors Fruendlich isotherm and imply
pseudo – kinetic second order which applied chemisorptions
Abstract: The purpose of this research is to establish the experimental conditions for removal of Cibacron Brilliant Yellow 3G-P dye (CBY) from aqueous solutions by sorption onto coffee husks as a low-cost sorbent. The effects of various experimental parameters (e.g. initial CBY dye concentration, sorbent mass, pH, temperature) were examined and the optimal experimental conditions were determined. The results indicated that the removal of the dye was pH dependent and at initial pH of 2, the dye was removed effectively. The CBY dye sorption data were fitted to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich equilibrium models. The maximum sorption capacity of CBY dye ions onto coffee husks increased from 24.04 to 35.04 mg g-1 when the temperature was increased from 293 to 313 K. The calculated sorption thermodynamic parameters including ΔG°, ΔH°, and ΔS° indicated that the CBY dye sorption onto coffee husks is a spontaneous, endothermic and mainly physical in nature.
Abstract: Salinity level may affect early development of
biofuel feedstock crops. The biofuel feedstock crops canola
(Brassica napus L.), sorghum [Sorghum bicolor (L.) Moench], and
sunflower (Helianthus annuus L.); and the potential feedstock crop
sweet corn (Zea mays L.) were planted in media in pots and treated
with aqueous solutions of 0, 0.1, 0.5 and 1.0 M NaCl once at: 1)
planting; 2) 7-10 days after planting or 3) first true leaf expansion.
An additional treatment (4) comprised of one-half strength of the 0.1,
0.5 and 1.0 M (concentrations 0.05, 0.25, 0.5 M at each application)
was applied at first true leaf expansion and four days later. Survival
of most crops decreased below 90% above 0.5 M; survival of canola
decreased above 0.1 M. Application timing had little effect on crop
survival. For canola root fresh and dry weights improved when
application was at plant emergence; for sorghum top and root fresh
weights improved when the split application was used. When
application was at planting root dry weight was improved over most
other applications. Sunflower top fresh weight was among the
highest when saline solutions were split and top dry weight was
among the highest when application was at plant emergence. Sweet
corn root fresh weight was improved when the split application was
used or application was at planting. Sweet corn root dry weight was
highest when application was at planting or plant emergence. Even at
high salinity rates survival rates greater than what might be expected
occurred. Plants that survived appear to be able to adjust to saline
during the early stages of development.
Abstract: In the present work, we have developed a symmetric electrochemical capacitor based on the nanostructured iron oxide (Fe3O4)-activated carbon (AC) nanocomposite materials. The physical properties of the nanocomposites were characterized by Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. The electrochemical performances of the composite electrode in 1.0 M Na2SO3 and 1.0 M Na2SO4 aqueous solutions were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The composite electrode with 4 wt% of iron oxide nanomaterials exhibits the highest capacitance of 86 F/g. The experimental results clearly indicate that the incorporation of iron oxide nanomaterials at low concentration to the composite can improve the capacitive performance, mainly attributed to the contribution of the pseudocapacitance charge storage mechanism and the enhancement on the effective surface area of the electrode. Nevertheless, there is an optimum threshold on the amount of iron oxide that needs to be incorporated into the composite system. When this optimum threshold is exceeded, the capacitive performance of the electrode starts to deteriorate, as a result of the undesired particle aggregation, which is clearly indicated in the SEM analysis. The electrochemical performance of the composite electrode is found to be superior when Na2SO3 is used as the electrolyte, if compared to the Na2SO4 solution. It is believed that Fe3O4 nanoparticles can provide favourable surface adsorption sites for sulphite (SO3 2-) anions which act as catalysts for subsequent redox and intercalation reactions.
Abstract: Potassium monopersulfate has been decomposed in aqueous solution in the presence of Co(II). The process has been simulated by means of a mechanism based on elementary reactions. Rate constants have been taken from literature reports or, alternatively, assimilated to analogous reactions occurring in Fenton's chemistry. Several operating conditions have been successfully applied.
Abstract: Composite of Celatom-ZeoliteY (Cel-ZY) was used to
remove cobalt ion from an aqueous solution using batch mode.
ZeoliteY has successfully superimposed on Celatom FW-14 surface
using hydrothermal treatment .The product was synthesized as a
novel of hierarchical porous material. It was observed from the
results that Cel-ZY has higher ability to remove cobalt ions than the
pure ZeoliteY powder (PZY) synthesized under the same conditions.
Several parameters were studied in this project to investigate the
effect of removal cobalt ion such as pH and initial cobalt
concentration. It was clearly observed that the uptake of cobalt ions
was affected with increase these parameters. The results proved that
the product can be used effectively to remove Co2+ ions from
wastewater as an environmentally friendly alternative.
Abstract: In this study, the sorption of Malachite green (MG) on Hydrilla verticillata biomass, a submerged aquatic plant, was investigated in a batch system. The effects of operating parameters such as temperature, adsorbent dosage, contact time, adsorbent size, and agitation speed on the sorption of Malachite green were analyzed using response surface methodology (RSM). The proposed quadratic model for central composite design (CCD) fitted very well to the experimental data that it could be used to navigate the design space according to ANOVA results. The optimum sorption conditions were determined as temperature - 43.5oC, adsorbent dosage - 0.26g, contact time - 200min, adsorbent size - 0.205mm (65mesh), and agitation speed - 230rpm. The Langmuir and Freundlich isotherm models were applied to the equilibrium data. The maximum monolayer coverage capacity of Hydrilla verticillata biomass for MG was found to be 91.97 mg/g at an initial pH 8.0 indicating that the optimum sorption initial pH. The external and intra particle diffusion models were also applied to sorption data of Hydrilla verticillata biomass with MG, and it was found that both the external diffusion as well as intra particle diffusion contributes to the actual sorption process. The pseudo-second order kinetic model described the MG sorption process with a good fitting.
Abstract: The paper reports the preparation and photocatalytic
activity of ZnO/SnO2 and SnO2 nanoparticles. These nanoparticles
were synthesized by hydrothermal method. The products were
characterized by X-ray diffraction (XRD) and scanning electron
microscopy (SEM). Their grain sizes are about 50-100 nm. The
photocatalytic activities of these materials were investigated for
congo red removal from aqueous solution under UV light irradiation.
It was shown that the use of ZnO/SnO2 as photocatalyst have better
photocatalytic activity for degradation of congo red than SnO2 or
TiO2 (anatase, particle size: 30nm) alone.
Abstract: Potassium monopersulfate has been decomposed in
aqueous solution in the presence of Co(II). The effect of the main
operating variables has been assessed. Minimum variations in pH
exert a considerable influence on the process kinetics. Thus, when no
pH adjustment is considered, the actual effect of variables like initial
monopersulfate and/or catalyst concentration may be hindered. As
expected, temperature enhances the monopersulfate decomposition
rate by following the Arrhenius law. The activation energy in the
proximity of 85 kJ/mol has been obtained. Amongst the different
solids tested in the monopersulfate decomposition, only the
perovskite LaTi0.15Cu0.85O3 has shown a significant catalytic activity.
Abstract: In this study, a low temperature sensor highly selective to CO in presence of methane is fabricated by using 4 nm SnO2 quantum dots (QDs) prepared by sonication assisted precipitation. SnCl4 aqueous solution was precipitated by ammonia under sonication, which continued for 2 h. A part of the sample was then dried and calcined at 400°C for 1.5 h and characterized by XRD and BET. The average particle size and the specific surface area of the SnO2 QDs as well as their sensing properties were compared with the SnO2 nano-particles which were prepared by conventional sol-gel method. The BET surface area of sonochemically as-prepared product and the one calcined at 400°C after 1.5 hr are 257 m2/gr and 212 m2/gr respectively while the specific surface area for SnO2 nanoparticles prepared by conventional sol-gel method is about 80m2/gr. XRD spectra revealed pure crystalline phase of SnO2 is formed for both as-prepared and calcined samples of SnO2 QDs. However, for the sample prepared by sol-gel method and calcined at 400°C SnO crystals are detected along with those of SnO2. Quantum dots of SnO2 show exceedingly high sensitivity to CO with different concentrations of 100, 300 and 1000 ppm in whole range of temperature (25- 350°C). At 50°C a sensitivity of 27 was obtained for 1000 ppm CO, which increases to a maximum of 147 when the temperature rises to 225°C and then drops off while the maximum sensitivity for the SnO2 sample prepared by the sol-gel method was obtained at 300°C with the amount of 47.2. At the same time no sensitivity to methane is observed in whole range of temperatures for SnO2 QDs. The response and recovery times of the sensor sharply decreases with temperature, while the high selectivity to CO does not deteriorate.
Abstract: The present work was conducted for Arsenic (III)
removal, which one of the most poisonous groundwater pollutants, by
synthetic nano size zerovalent iron (nZVI). Batch experiments were
performed to investigate the influence of As (III), nZVI
concentration, pH of solution and contact time on the efficiency of As
(III) removal. nZVI was synthesized by reduction of ferric chloride
by sodium borohydrid. SEM and XRD were used to determine
particle size and characterization of produced nanoparticles. Up to
99.9% removal efficiency for arsenic (III) was obtained by nZVI
dosage of 1 g/L at time equal to 10 min. and pH=7. It could be
concluded that the removal efficiency were enhanced with increasing
of ZVI dosage and reaction time, but decreased with increasing of
arsenic concentration and pH for nano sized ZVI. nZVI presented an
outstanding ability to remove As (III) due to not only a high surface
area and low particle size but also to high inherent activity.
Abstract: An interesting method to produce calcium carbonate is based in a gas-liquid reaction between carbon dioxide and aqueous solutions of calcium hydroxide. The design parameters for gas-liquid phase are flow regime, individual mass transfer, gas-liquid specific interfacial area. Most studies on gas-liquid phase were devoted to the experimental determination of some of these parameters, and more specifically, of the mass transfer coefficient, kLa which depends fundamentally on the superficial gas velocity and on the physical properties of absorption phase. The principle investigation was directed to study the effect of the vibration on the mass transfer coefficient kLa in gas-liquid phase during absorption of CO2 in the in aqueous solution of calcium hydroxide. The vibration with a higher frequency increase the mass transfer coefficient kLa, but vibration with lower frequency didn-t improve it, the mass transfer coefficient kLa increase with increase the superficial gas velocity.
Abstract: This study deals with evaluation of influence of salinity (NaCl) onto equilibrium of Cu and Ni removal from aqueous solutions by natural sorbent – zeolite. Equilibrium data were obtained by batch experiments. The salinity of the aqueous solution was influenced by dissolving NaCl in distilled water. It was studied in the range of NaCl concentrations from 1 g.l-1 to 100g.l-1. For Cu sorption there is a significant influence of salinity. The maximum capacity of zeolite for Cu was decreasing with growing concentration of NaCl. For Ni sorption there is not so significant influence of salinity as for Cu. The maximum capacity of zeolite for Ni was slightly decreasing with growing concentration of NaCl.
Abstract: The equilibrium, thermodynamics and kinetics of the
biosorption of Cd (II) and Pb(II) by a Spore Forming Bacillus (MGL
75) were investigated at different experimental conditions. The
Langmuir and Freundlich, and Dubinin-Radushkevich (D-R)
equilibrium adsorption models were applied to describe the
biosorption of the metal ions by MGL 75 biomass. The Langmuir
model fitted the equilibrium data better than the other models.
Maximum adsorption capacities q max for lead (II) and cadmium (II)
were found equal to 158.73mg/g and 91.74 mg/g by Langmuir model.
The values of the mean free energy determined with the D-R equation
showed that adsorption process is a physiosorption process. The
thermodynamic parameters Gibbs free energy (ΔG°), enthalpy (ΔH°),
and entropy (ΔS°) changes were also calculated, and the values
indicated that the biosorption process was exothermic and
spontaneous. Experiment data were also used to study biosorption
kinetics using pseudo-first-order and pseudo-second-order kinetic
models. Kinetic parameters, rate constants, equilibrium sorption
capacities and related correlation coefficients were calculated and
discussed. The results showed that the biosorption processes of both
metal ions followed well pseudo-second-order kinetics.
Abstract: Characteristics and sonocatalytic activity of zeolite
Y catalysts loaded with TiO2 using impregnation and ion exchange
methods for the degradation of amaranth dye were investigated.
The Ion-exchange method was used to encapsulate the TiO2 into
the internal pores of the zeolite while the incorporation of TiO2
mostly on the external surface of zeolite was carried out using the
impregnation method. Different characterization techniques were
used to elucidate the physicochemical properties of the produced
catalysts. The framework of zeolite Y remained virtually
unchanged after the encapsulation of TiO2 while the crystallinity of
zeolite decreased significantly after the incorporation of 15 wt% of
TiO2. The sonocatalytic activity was enhanced by TiO2
incorporation with maximum degradation efficiencies of 50% and
68% for the encapsulated titanium and titanium loaded onto the
zeolite, respectively after 120min of reaction. Catalysts
characteristics and sonocatalytic behaviors were significantly
affected by the preparation method and the location of TiO2
introduced with zeolite structure. Behaviors in the sonocatalytic
process were successfully correlated with the characteristics of the
catalysts used.