Multi-walled and single-walled carbon nanotubes were used as nanoadsorbents for the successful removal of Reactive Blue 4 textile dye from aqueous solutions. The adsorbents were characterised by infrared and Raman spectroscopy, N(2) adsorption/desorption isotherms and scanning and transmission electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium isotherms at 298-323 K was fixed at 4 hours for both adsorbents. The general order kinetic model provided the best fit to the experimental data compared with pseudo-first order and pseudo-second order kinetic adsorption models. For Reactive Blue 4 dye, the equilibrium data (298 to 323 K) were best fitted to the Liu isotherm model. The maximum sorption capacity for adsorption of the dye occurred at 323 K, attaining values of 502.5 and 567.7 mg g(-1) for MWCNT and SWCNT, respectively. Simulated dyehouse effluents were used to check the applicability of the proposed nanoadsorbents for effluent treatment (removal of 99.89% and 99.98%, for MWCNT and SWCNT, respectively). The interaction of Reactive Blue 4 textile dye with single-walled carbon nanotubes (SWCNTs) was investigated using first principles calculations based on density functional theory. Results from ab initio calculations indicated that Reactive Blue 4 textile dye could be adsorbed on SWCNT through an electrostatic interaction; these results are in agreement with the experimental predictions.

The interactions of sodium diclofenac drug (s-DCF) with different graphene species were investigated using both first principles calculations based on Density Functional Theory (DFT) and adsorption experiments. Through batch adsorption experiments, it was found that rGO was a good adsorbent for removing the s-DCF drug from aqueous solutions. The general-order kinetic model shows the best fit to the experimental data compared with pseudo-first order and pseudo-second order kinetic adsorption models. The equilibrium data (at 25 °C) were fitted to the Liu isotherm model. The maximum sorption capacity for adsorption of the s-DCF drug was 59.67 mg g(-1) for rGO. The s-DCF adsorption onto pristine graphene, graphene with a vacancy, reduced oxide graphene (rGO) and functionalized graphene nanoribbons were simulated providing a good understanding of the adsorption process of this molecule on graphene-family surfaces. The results predict a physisorption regime in all cases. Based on these results, the ab initio calculations and the adsorption experiments point out that the graphene-family are promising materials for extracting s-DCF from wastewater effluents.

This study evaluated the feasibility of removing Alizarin Red S dye (ARS) from aqueous solutions, using nanoadsorbents such as single and multiwalled carbon nanotubes (SWCNT and MWCNT, respectively). The effect of pH, shaking time, and temperature on adsorption was studied. The pH 2.0 was observed to show optimum removal for both of the carbon nanotubes. The equilibrium time (298−318 K) was fixed at 65 and 100 min for SWCNT and MWCNT, respectively. The kinetics of adsorption was calculated using pseudo-first-order, pseudo-second-order, and general-order equations. The calculations revealed that the general-order kinetic equation best-fit the adsorption data. The Liu isotherm model best fit the equilibrium data (298−318 K). The maximum sorption capacity at 318 K for ARS dye was 312.5 and 135.2 mg g −1 for SWCNT and MWCNT, respectively. Change in entropy (ΔS°), Gibb's free energy change (ΔG°), and enthalpy (ΔH°) were calculated for the adsorption of ARS dye. The electrostatic interaction between nanoadsorbent−adsorbate was conveyed using the magnitude of change in enthalpy. Ab initio simulation was used to study the interaction of ARS with (5,5) and (8,0) SWCNTs, and (16,0) and (25,0) SWCNTs with and without vacancy. The theoretical calculations showed that the binding energies between ARS dye and SWCNTs are enhanced as the nanotube diameter gets bigger; however, the distance of binding remains unchanged. Therefore, the results from first principle calculations indicated that electrostatic interaction may be responsible for the adsorption of ARS dye onto SWCNT. The theoretical outcomes were found to be in coordination with the experimental estimates.

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Interactions of anti-inflammatory nimesulide (NM) with different graphene material species were explored employing both ab initio calculations, based on Density Functional Theory (DFT), and a batch adsorption process. The adsorption of NM onto graphene, with and without a vacancy, reduced graphene oxide (rGO) and functionalized graphene nanoribbons was simulated, providing a good understanding of the adsorption process of the NM molecule onto graphene material surfaces. The theoretical results indicate a physisorption interaction between NM and all of the evaluated adsorbents. Based on batch adsorption experiments, it was found that rGO, obtained via a modified Hummers method, is a good nanoadsorbent for the removal of the anti-inflammatory NM from aqueous solutions. The general-order kinetic equation displays the best fit to the experimental data compared with pseudo-first order and pseudo-second order kinetics. The equilibrium data fitted well into the Liu isotherm equation, and the maximum sorption capacity for the adsorption of NM by rGO was 82.4 mg g at 25 °C. Our results of the first principle calculations and the batch adsorption experiments point out that graphene materials are promising nanomaterials for extracting NM from aqueous solutions.

This work aimed to combine different experiments and multi-scale theoretical approaches to understand the adsorption process of methylene blue in three-dimensional graphene-based materials. For this, experiments were carried out on...

The qualities of waters are constantly diminishing due to release of toxic components into the environment. It is very important to treat wastewater in order to remove pollutants and improve water quality. Generally, adsorption technology has proven to be one of the most effective techniques in the separation and removal of a wide variety of organic and inorganic pollutants from wastewater. Recently, carbon nanomaterials such as fullerene, carbon nanotubes (CNT) and graphene-family have become promising adsorbents for water treatment. This chapter compiles relevant knowledge about the experimental and theoretical adsorption activities of fullerene, CNT and graphene-family as nanoadsorbents for removal of organic and inorganic environmental pollutants.

Este trabalho apresenta as experiências obtidas por docentes e discentes da UNIFRA na produção e aplicação de objetos de aprendizagem interativos desenvolvidos segundo a metodologia RIVED, Rede Interativa Virtual de Educação, para a área de física. O material didático “Custo do Banho” foi desenvolvido com recursos pedagógicos, de conteúdo e de tecnologias multimídias e tem demonstrado ser uma ferramenta interessante para subsidiar o entendimento de quantidades físicas como vazão e potência elétrica calculando o custo de um banho.