Multi-walled Carbon Nanotubes Dosage Research Articles

Adsorption of Bismarck Brown R Dye Onto Multiwall Carbon Nanotubes

In this work, Multiwall carbon nanotubes (MWCNTs) were used in the adsorptive removal of Bismarck Brown R (BBR) dye from an aqueous solution. The effects of contact time, MWCNT dosage, dye concentration, pH and temperature on adsorption of BBR dye by MWCNTs were investigated. The adsorption study was analyzed kinetically, and the results revealed that the adsorption followed pseudo-second order kinetics with good correlation coefficients. The equilibrium adsorption data was analyzed using three common adsorption models: Langmuir, Freundlich and Temkin. Gibbs free energy change values showed that the adsorptions of BBR dye on MWCNTs is spontaneous. The results also indicate that the adsorption is physisorption.

Adsorption of reactive blue 29 dye from aqueous solution by multiwall carbon nanotubes

AbstractIndustrial effluents that carry dyestuff into natural water systems are serious environmental concern. The complex aromatic structures of dyes make them more stable and more difficult to remove from the effluents discharged into water bodies. Dyes are known pollutants that not only affecting esthetic merit but also reducing light penetration and photosynthesis, and some are considered toxic and even carcinogenic for human health. This study examined the feasibility of removing reactive blue 29 dye (RB29) from aqueous solutions using multiwall carbon nanotubes (MWCNTs) and oxidized MWCNTs. The effects of RB29 dye concentration, MWCNT and MWCNT-COOH dosage, and pH on adsorption of RB29 by both MWCNTs and MWCNT-COOH were also evaluated. Also, the adsorption isotherms of this dye on to carbon nanotubes (CNTs) and related constants were studied. Results showed that adsorption capacity of pristine MWCNTs was higher than oxidized MWCNTs due to negative charge put on the surface of MWCNT-COOH. The adsorpt...

Adsorption of Acid Blue 161 (AB 161) Dye from Water by Multi-walled Carbon Nanotubes

The adsorption properties of acid blue 161 (AB 161) from aqueous solution onto multi-walled carbon nanotubes (MWCNTs) was studied as a function of time, pH and initial AB 161 concentration. The maximum adsorption yield (91.68%) was obtained at the conditions of pH 3.0, MWCNTs dosage of 0.1 g/L, contact time of 60 minutes, for initial AB 161 concentration of 50 mg/L and temperature of 25°C. Also, Langmuir, Freundlich and Temkin isotherms and three kinetic models were applied to fit the experimental data. Both Freundlich and Temkin models agree well with experimental data. The adsorption capacity of MWCNT was compared with activated carbon (AC). The results suggest that MWCNTs have good potential application in dye adsorption.

Kinetics and thermodynamic study of aniline adsorption by multi-walled carbon nanotubes from aqueous solution

Multi-walled carbon nanotubes (MWCNTs) were used in the adsorptive removal of aniline, an organic pollutant, from an aqueous solution. It was found that carbon nanotubes with a higher specific surface area adsorbed and removed more aniline from an aqueous solution. The adsorption was dependent on factors, such as MWCNTs dosage, contact time, aniline concentration, solution pH and temperature. The adsorption study was analyzed kinetically, and the results revealed that the adsorption followed pseudo-second order kinetics with good correlation coefficients. In addition, it was found that the adsorption of aniline occurred in two consecutive steps, including the slow intra-particle diffusion of aniline molecules through the nanotubes. Various thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), were calculated. The results indicated that the spontaneity of the adsorption, exothermic nature of the adsorption and the decrease in the randomness reported as ΔG°, ΔH° and ΔS°, respectively, were all negative.

Removal of mercury from water by multi-walled carbon nanotubes

The removal of mercury (Hg(2+)) ions from contaminated water using multiwalled carbon nanotubes (MWCNTs) was investigated in this study. Results of the study showed that MWCNTs slurry was very efficient in removing as high as 1.0 mg/L of Hg(2+) from aqueous solutions via the adsorption mechanism. This removal efficiency was found to be a function of the aqueous pH level, dosage of CNTs, mixing rate, and contact time. The study showed that the Hg uptake by MWCNTs increased to 100% with an increase in pH from pH 4 to 8. The results also showed that higher dosage of MWCNTs, showed higher removal of Hg(2+). In a 50 mL water sample, 10 mg of MWCNTs was needed to remove all of the 0.1 mg/L of Hg(2+) ions. On the other hand, increasing the mixing rate from 50 to 150 rpm improved the removal efficiency. The experimental results also showed that mercury adsorption by MWCNTs follow a pseudo second-order reaction with a rate (k) of 0.018 and it is well described by the Langmuir isotherm model with maximum adsorptive capacity (q(max)) of 13.16.

Adsorption and Reduction of Chromium(VI) from Aqueous Solution by Multiwalled Carbon Nanotubes

The adsorption of Cr(VI) on the raw multiwalled carbon nanotubes (MWCNTs) as a function of initial Cr(VI) concentration, pH, temperature, and MWCNT dosage were studied. The removal of Cr(VI) from aqueous solution was dominated by adsorption of Cr(VI) and redox reaction of Cr(VI) to Cr(III). The adsorption of Cr(VI) decreased with in- creasing pH and increased with the rise in temperature and MWCNT dosage. The adsorption data of Cr(VI) on MWCNTs could be described well by Langmuir isotherm model. The thermodynamic values of Gibbs free energy ( G o ), enthalpy ( H o ), and entropy ( S o ) were calculated from temperature-dependent adsorption data, and the results indicated that the adsorption of Cr(VI) on the raw MWCNTs was a spontaneous process. The results suggest that MWCNTs are suitable materials in the preconcentration and solidification of Cr(VI) from large volume of solutions.