Adsorption of phenol and o-chlorophenol by mesoporous MCM-41.
ABSTRACT Water pollution by toxic organic compounds is of concern and the demand for effective adsorbents for the removal of toxic compounds is increasing. Present work deals with the adsorption of phenol (PhOH) and o-chlorophenol (o-CP) on mesoporous MCM-41 material. The effect of surfactant template in MCM-41 on the removal of PhOH and o-CP was investigated. The comparison of adsorption of PhOH and o-CP on uncalcined MCM-41 (noted as MCM-41) and calcined MCM-41 (noted as C-MCM-41) was investigated. It was found that MCM-41 shows significant adsorption for PhOH and o-CP as compared to C-MCM-41, this may be because of the hydrophobicity created by surfactant template in the MCM-41. Batch adsorption studies were carried out to study the effect of various parameters like adsorbent dose, pH, initial concentration and the presence of co-existing ions. It was found that adsorption of PhOH and o-CP depends upon the solution pH as well as co-existing ions present in the aqueous solution. The equilibrium adsorption data for PhOH and o-CP was analyzed by using Freundlich adsorption isotherm model. From the sorption studies it was observed that the uptake of o-CP was higher than PhOH.
- Bone 01/2011; 48. · 3.82 Impact Factor
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ABSTRACT: This work tested the effect of the addition of Al(2)O(3)/GdAlO(3) longitudinal fibers in different contents to veneering porcelain of two dental all ceramic systems. Fibers (0.5 mm diameter) obtained by the Laser Heated Pedestal Growth (LHPG) method were added to bar-shaped specimens made by veneer porcelain (monolayers) or both the veneer and the core ceramic (bilayers) of two all-ceramic systems: In-Ceram Alumina-glass infiltrated alumina composite (GIA) and In-Ceram 2000 AL Cubes-alumina polycrystal (AP) (VITA Zahnfabrik). The longitudinal fibers were added to veneering porcelain (VM7) in two different proportions: 10 or 17 vol%. The bars were divided into nine experimental conditions (n=10) according to material used: VM7 porcelain monolayers, VM7/GIA, VM7/AP; and according to the amount of fibers within the porcelain layer: no fibers, 10 vol% or 17 vol%. After grinding and polishing the specimens were submitted to a three point bending test (crosshead speed = 0.5 mm/min) with porcelain positioned at tensile side. Data were analyzed by means of one-way ANOVA and a Tukey's test (α=5%). Scanning electronic microscopy (SEM) was conducted for fractographic analysis. Regarding the groups without fiber addition, VM7/AP showed the highest flexural strength (MPa), followed by VM7/GIA and VM7 monolayers. The addition of fibers led to a numerical increase in flexural strength for all groups. For VM7/GIA bilayers the addition of 17 vol% of fibers resulted in a significant 48% increase in the flexural strength compared to the control group. Fractographic analysis revealed that the crack initiation site was in porcelain at the tensile surface. Cracks also propagated between fibers before heading for the alumina core. The addition of 17 vol% of Al(2)O(3)/GdAlO(3) longitudinal fibers to porcelain/glass infiltrated alumina bilayers significantly improved its flexural strength. 10 vol% or 17 vol% of fibers inclusion increased the flexural strength for all groups.Journal of the mechanical behavior of biomedical materials. 01/2012; 5(1):110-5.
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ABSTRACT: Thiol-functionalized MCM-41 mesoporous silicas were synthesized via evaporation-induced self-assembly. The mesoporous silicas obtained were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption analysis, Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The products were used as adsorbents to remove heavy metal ions from water. The mesoporous silicas (adsorbent A) with high pore diameter (centered at 5.27nm) exhibited the largest adsorption capacity, with a BET surface area of 421.9m2g−1 and pore volume of 0.556cm3g−1. Different anions influenced the adsorption of Cu(II) in the order NO3 −<OAc−<SO4 2−<CO3 2−<Cit−<Cl−. Analysis of adsorption isotherms showed that Cu2+, Pb2+, Ag+, and Cr3+ adsorption fit the Redlich–Peterson nonlinear model. The mesoporous silicas synthesized in the work can be used as adsorbents to remove heavy metal ions from water effectively. The removal rate was high, and the adsorbent could be regenerated by acid treatment without changing its properties. KeywordsMesoporous silicas-Adsorbent-Heavy metal-Regeneration-Adsorption-Environmental remediation-EHSJournal of Nanoparticle Research 04/2012; 12(6):2111-2124. · 2.18 Impact Factor