Alireza Nouri; Ramin Yavari; Mohammad Ali Aroon; Taher Yousefi
Abstract
In the present research work, the mixed matrix membranes (MMMs) containing various amount of polyethersulfone (PES) and functionalized multi-walled carbon nanotubes (fMWCNTs) were fabricated and used to investigate the removal of cobalt ions from wastewater by nanofiltration process. Pristine MWCNTs ...
Read More
In the present research work, the mixed matrix membranes (MMMs) containing various amount of polyethersulfone (PES) and functionalized multi-walled carbon nanotubes (fMWCNTs) were fabricated and used to investigate the removal of cobalt ions from wastewater by nanofiltration process. Pristine MWCNTs and fMWCNTs were characterized by Fourier transformed infrared spectroscopy and thermogravimetric analysis. FESEM analysis revealed that the mixed matrix membranes have less surface defects and better membrane performance compared with neat polymeric in the removal of cobalt ions. Permeation test results showed that the MMM containing 22 wt. % PES and 0.6 wt. % fMWCNTs (with outer diameter of 10-20 nm) has the optimum performance from the permeability and cobalt removal point of view. In continuation, the effect of pressure, feed flow rate, cobalt concentration, permeation test time and feed solution pH on the removal of cobalt by selected the MMM was investigated. The obtained results indicated that only pressure has considerable effect on permeation flux. However, all parameters showed different influence on rejection percent of cobalt ions.
Kamal Alizadeh; Esmail Khaledyan; Yagoub Mansourpanah
Abstract
In this study, a selective, fast and novel magnetic mesoporous silica sorbent Fe3O4@MCM-41-NH2, was synthesized, functionalized and has been used for the removal of Pb+2 ions from aqueous solution. The characteristics of the Fe3O4@MCM-41-NH2 sorbent was investigated by XRD, VSM, SEM, TEM, ...
Read More
In this study, a selective, fast and novel magnetic mesoporous silica sorbent Fe3O4@MCM-41-NH2, was synthesized, functionalized and has been used for the removal of Pb+2 ions from aqueous solution. The characteristics of the Fe3O4@MCM-41-NH2 sorbent was investigated by XRD, VSM, SEM, TEM, BET, and FT-IR. The response surface methodology (RSM) based on central composite design (CCD) was utilized for estimating the effects of parameters, namely contact time (min), pH, the quantity of adsorbent (g) and initial concentration of Pb+2. The quadratic model was used as the best model for guessing variables. The results of the analysis of variance for this model were obtained with a high F-value (50.28), very low P-value (<0.0001) and non-significant lack of fit (0.2251). The maximum adsorption capacity was obtained at 46.08 mg/L. Fitting equilibrium data with different isotherm models shows that Freundlich isotherm was the best-fitted model. The pseudo-second-order model was the best model for fitting experimental data.
Reza Tayebee; vahid Mazruy
Abstract
The limited adsorption capacity of natural clays is a crucial and economic issue which confined their applications in industry as cheap adsorbents to remove toxic contaminants from wastewaters. Here, the adsorption capacity of a natural nano bentonite was enhanced by a simple acid and thermal activation ...
Read More
The limited adsorption capacity of natural clays is a crucial and economic issue which confined their applications in industry as cheap adsorbents to remove toxic contaminants from wastewaters. Here, the adsorption capacity of a natural nano bentonite was enhanced by a simple acid and thermal activation and the manufactured nano-adsorbent was characterized by FESEM, BET, FT-IR, and XRD. Effects of pH, temperature, sorbent capacity, and the initial concentration of malachite green were examined. The isotherm behavior of the adsorption system was investigated by the Langmuir and Freundlich isotherm models. Also, the kinetic inspections demonstrated that the adsorption of malachite green matched with the pseudo-second-order kinetic and the obtained thermodynamic parameters H, S, and G showed that the adsorption of malachite green was a spontaneous and endothermic process. The results indicated that the acid-thermal activated nano bentonite, with an enhanced surface area of >220 m2/g, can be depleted as a powerful and low-cost adsorbent to expel malachite green from aqueous solutions.
Shahryar Jafarinejad; Mohammad Faraji; Zohreh Norouz; Javad Mokhtari-Aliabad
Abstract
Even at low levels, heavy metals are toxic and can damage living things. They do not break down or decompose and tend to build up in plants, animals, and people causing health concerns. Magnetic nanoparticles (MNPs) can be considered as potential adsorbents for the removal of cadmium (Cd2+) from aqueous ...
Read More
Even at low levels, heavy metals are toxic and can damage living things. They do not break down or decompose and tend to build up in plants, animals, and people causing health concerns. Magnetic nanoparticles (MNPs) can be considered as potential adsorbents for the removal of cadmium (Cd2+) from aqueous solutions because of their high surface area and the combined effect of adsorption and separation under external magnetic fields. In this study, a novel sulfur-modified magnetic nanoparticle was applied as an adsorbent for the removal of Cd2+ ions from aqueous solutions. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). The effects of pH, contact time, and initial concentration of Cd2+ on the removal efficiency of it were investigated in batch adsorption experiments. The equilibrium data fitted the Langmuir isotherm model better than the Freundlich isotherm model, and they were well explained in terms of pseudo-second-order kinetics. The maximum monolayer capacity qm and KL the Langmuir constant were calculated from the Langmuir as 5.1867 mg/g and 0.1562 L/mg, respectively.
Mohammad Taghi Kouhiyan Afzal; Ahmad Farrokhian Firouzi; Mehdi Taghavi
Abstract
Zero-valent iron particles at the nanoscale are proposed to be one of the important reductants of Cr(VI), transforming the same into nontoxic Cr(III). In this study zero valent iron nanoparticles(ZVINs) were synthesized and characterized for hexavalent chromium removal from aqueous solutions. Five different ...
Read More
Zero-valent iron particles at the nanoscale are proposed to be one of the important reductants of Cr(VI), transforming the same into nontoxic Cr(III). In this study zero valent iron nanoparticles(ZVINs) were synthesized and characterized for hexavalent chromium removal from aqueous solutions. Five different zero-valent iron nanoparticle types comprising of bare and stabilized ZVINs with poly acrylamide(PAM), polyvinyl pyrrolidone(PVP), polystyrene sulfonate(PSS) and guar gum(GG) were synthesized and employed in this study. The sizes of zero-valent iron nanoparticles were found to be 40, 14, 17, 29 and 34nm, using transmission electron microscopy (TEM), corresponding to bare zero valent iron nanoparticles(ZVINs), poly acrylamide(PAM), guar gum(GG), poly styrene solfunate(PSS) and polyvinyl pyrrolidone(PVP) stabilized zero valent iron nanoparticles (ZVINs) respectively. The trend in the sizes of ZVINs with various stabilizers in the decreasing order was found to be bare ZVIN > PVP-ZVIN >PSS-ZVIN> GG-ZVIN> PAM-ZVIN respectively. Results showed that by increasing hexavalent chromium concentrations from 20 to 100 mg/L, the Cr(VI) efficiency removal decreased significantly. When the ZVINs concentrations increased from 2 to 10 gr/L(0.1 to 0.5g per 50 mL), the Cr(VI) removal efficiency enhanced. The most effective treatments of ZVINs and Cr(VI) for hexavalent chromium removal from solutions were 10 gr/lit (0.5g per 50 mL) and 20 mg/L respectively, so the efficiency of bare and polymer stabilized-ZVINs on Cr(VI) removal from solutions was found to be in the following order: bare ZVINs < PVP-ZVINs <PSS-ZVINs< GG-ZVINs< PAM-ZVINs.
Susan Samadi; Rokhsareh Motallebi; Maryam Nasiri Nasrabadi
Abstract
The efficient application of the photocatalytic activity and superficial adsorption on removing heavy metals from water, two types of sorbents, Nd-TiO2/bentonite and Ce-TiO2/bentonite nanocomposites, were synthesized by sol-gel method. The crystalline nanocomposites were obtained after heat treatment ...
Read More
The efficient application of the photocatalytic activity and superficial adsorption on removing heavy metals from water, two types of sorbents, Nd-TiO2/bentonite and Ce-TiO2/bentonite nanocomposites, were synthesized by sol-gel method. The crystalline nanocomposites were obtained after heat treatment at 500 °C for 3 hours. The results of scanning electron microscopy (SEM) indicates that Nd-TiO2/bentonite and Ce-TiO2/bentonite were produced on a nanoscale. The phase change of both nanocomposite from amorphous to anatase has been investigated by X- ray diffraction. Removal of lead (II) and cadmium (II) were studied through adsorption on these nanocomposites by letting them float in the bulk of sample for a definite time in presence and absence of light. The effective parameters in removal process were studied and optimized. The optimum pH, removal time and sorbent dosage in the absence and presence of light for Pb2+ ion were 7, 0.3 g, 15 min and for Cd2+ ion were 7, 0.4 g, 20 min, respectively. Subsequently, the effect of interfering ions in removal process was investigated at optimum conditions and no evidence of interference was observed. The study showed that reproducibility of method (n=9) is good and suitable. The results further indicated that the removal efficiency of Pb2+ ion with Nd-TiO2/bentonite in the presence of light was more than that in the absence of light. Finally, the equilibrium adsorption data fitted Freundlich and Langmuir adsorption models.