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In this research, a manganese dioxide/multiwalled carbon nanotube (MnO2/MWCNT) was firstly synthesized and characterized and then was applied as an effective sorbent for removing Cu2+ ions from aqueous solution. The effects of initial concentration, temperature, contact time, pH solution, and sorbent dosage were investigated and the optimum value of each was determined. The Langmuir isotherm model, Freundlich model, and Temkin model were used to fit our experimental results. Ultimately, using the Van't Hoff approach, the thermodynamic functions of the intended adsorption phenomenon such as ΔH°ad, ΔS°ad, and ΔG°ad were estimated.

In this research "MnO2/MWCNT" nanocomposite was prepared firstly and then it was used as an adsorbent for Cr +3 ions removal from aqueous solutions. Our results showed that the prepared nanocomposite from modified multi-wall carbon nanotube and MnO 2 has a good capacity for Cr +3 removal from aqueous solution. Morphology and Crystallinity of the modified MWCNT before and after deposition on MnO 2 were examined by SEM and XRD. In turn, the experimental results were examined according to the Langmuir, Freundlich and Temkin Isotherms and Freundlich isotherm represented our experimental results.

Ab initio density functional theory (DFT) calculations have been performed on the [3,3] sigmatropic rearrangement of substituted hexa-1,5-dienes (the Cope rearrangement) in the gas phase. The barrier heights calculated at the B3LYP=6-311G** level of theory were in a good agreement with experimental data. Optimized transition states at the B3LYP=6-311G** level were used to calculate nucleus-independent chemical shifts (NICS) and also natural bond orbital analysis (NBO) at the same level. Our results indicate that the aromaticities of the transition states are controlled by the out-of-plane component and these reactions are controlled kinetically by the aromaticity of the transition states. Based on the NBO analysis, the greater resonance energy for s ?p* and s ?s* delocalization in R2 (compared to R1 and R3) could facilitate the Cope rearrangement of R2. The greater s * 3À4 anti-bonding orbital occupancy and the lower s 3À4 bonding orbital occupancy in R1 could facilitate the Cope rearrangement of R1 compared to R3. Comparative examination between substituted and un-substituted hexa-1,5dienes show that in these reactions, steric parameters play no significant rule in the general mechanism of the Cope rearrangement. Figure 1 [3,3] sigmatropic rearrangement of substituted hexa-1,5-dienes (the Cope rearrangement) via two pathways (chair-like and boat-like).