REMOVAL OF INDIGO CARMINE DYE (IC) BY BATCH ADSORPTION METHOD ONTO DRIED COLA NUT SHELLS AND ITS ACTIVE CARBON FROM AQUEOUS MEDIUM

Natural cola nut shells and its active carbons were used to remove indigo carmine dye from aqueous solution using batch adsorption test. The effect of pH, contact time (t), adsorbent dose (m) and initial concentrations (Co) were investigated. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Tempkin and Dubin-Kaganer-Raduskushkevich classical isotherm models. This equilibrium data best fits with all the four isotherm models for cola nut shells. Langmuir and Freundlich equations correlated well with data obtained using activated carbon based H3PO4 while Freundlich and Tempkin best agreed with activated carbon based KOH. The kinetics of indigo carmine dye was discussed by pseudo-first order, pseudo-second order, Elovich and Intra-particle diffusion models. The pseudo-second order kinetic model equation fitted best to the data from all the three adsorbents. Elovich fitted best with data obtained using activated carbon based H3PO4 while intra-particle diffusion model for activated carbon based KOH. D-K-R shows that adsorption process was chemisorption for all the three adsorbents. Natural cola nut shells and activated carbon based KOH show higher adsorption capacities with indigo carmine compared to activated carbon based H3PO4. The results indicated that these shells and it active carbon can be used as an effective and low-cost adsorbent to remove indigo carmine from aqueous solution

How effectively bonding evolution theory retrieves and visualizes curly arrows: The cycloaddition reaction of cyclic nitrones

In the present work, the electron density flows involved throughout the progress of the four reaction pathways associated with the intramolecular [3 + 2] cycloaddition of cyclic nitrones Z-1 and E-1 are analyzed using the bonding evolution theory. The present study highlights the nonconcerted nature of the processes, which can be described as taking place in several stages. The first stage consists in the depopulation of the initial C N and C=C double bonds to render the N lone pair and the corresponding C-N and C-C single bonds, and these electronic flows initiate the reactions. The C-C and C-O sigma bond formations take place later on, once the transition states have been overcome. Along the bridged pathways, the C-C bond formation process precedes the O-C bond formation event, although, along the fused paths, the O-C bond formation process occurs first and the formation of the C-C bond is the last electronic flow to take place. Finally, curly arrow representations accounting for the timing of the electron flows are obtained from the bonding evolution theory results

The Adsorption Efficiency of Chemically Prepared Activated Carbon from Cola Nut Shells by on Methylene Blue

The adsorption of methylene blue from aqueous solution onto activated carbon prepared from cola nut shell has been investigated under batch mode. The influence of major parameters governing the efficiency of the process such as, solution pH, sorbent dose, initial concentration, and contact time on the removal process was investigated. The time-dependent experimental studies showed that the adsorption quantity of methylene blue increases with initial concentration and decreasing adsorbent dosage. The equilibrium time of 180 min was observed and maximum adsorption was favoured at pH 3.5. The dye removal using 0.1 g of adsorbent was more than 90%. This dosage (0.1 g) was considered as the optimum dosage to remove methylene blue from aqueous solutions. The equilibrium adsorption data were analyzed by the Freundlich, Langmuir adsorption isotherm models. The kinetics of methylene blue solution was discussed by pseudo-first-order, pseudo-second-order, and Elovich models. The adsorption process follows the Elovich rate kinetic model, having a correlation coefficient in the range between 0.9811 and 1

Modified Composite Activated Carbon Derived from Post-Consumer Plastics and Lignocellulosic Materials

The composite activated carbons were produced using both lignocellulosic materials and urban waste plastics and their characteristics were investigated. The mixture of raw material was first carbonized at 600ºC in N2 atmosphere. The char obtained was then mixed with KOH (in the ratio 2:1 for KOH/char) before the activation process with steam at 850ºC. The results show that composite carbons are micro, mesoporous and have higher carbon yield compared to the carbons from both pure raw materials, which are mainly mesoporous. These results were confirmed by their high adsorption of methylene blue. BET surface area for all the samples were over the acceptable range (991.5 - 1412.9). Moreover, the average size of the pores of carbon between in the range of 1.8 – 2.3 nm. Carbon surfaces were analyzed in detail using FTIR and SEM, exhibiting hydroxyl and carboxylic functional groups on the surfaces and cavities of mesopore size

Optimization of Activated Carbons Prepared by H3PO4 and Steam Activation of Oil Palm Shells

In this study, activated carbons were prepared from oil palm shells by physicochemical activation. The methodology of experimental design was used to optimize the preparation conditions. The influences of the impregnation ratio (0.6–3.4) and the activation temperature between 601°C and 799°C on the following three responses: activated carbon yield (R/AC-H3PO4), the iodine adsorption (I2/AC-H3PO4), and the methylene blue adsorption (MB/AC-H3PO4) results were investigated using analysis of variance (ANOVA) to identify the significant parameters. Under the experimental conditions investigated, the activation temperature of 770°C and impregnation ratio of 2/1 leading to the R/AC-H3PO4 of 52.10%, the I2/AC-H3PO4 of 697.86 mg/g, and the MB/AC-H3PO4 of 346.25 mg/g were found to be optimum conditions for producing activated carbon with well compromise of desirability. The two factors had both synergetic and antagonistic effects on the three responses studied. The micrographs of activated carbons examined with scanning electron microscopy revealed that the activated carbons were found to be mainly microporous and mesoporous

Étude des surfaces et calcul théorique des sites actifs de charbons actifs par adsorption de l'acide tartrique

The theoretical calculation of the number of active sites of four activated carbon samples (2SAP/C, COM3, NC 35 and NCF O.5/2) during the adsorption of tartaric acid from solution has revealed that the number of accessible active sites on the surface increases with increased pH. It also appears that the number of active sites for the basic activated carbon (NC 35 and NCF 0.5/2) is greater than that of the acidic activated carbon (2 SAP/C and COM 3). The results obtained are in agreement with those obtained by Freundlich and Langmuir models such that the classification for the four samples is as follows: 2 SAP/C < COM 3 < NC 35 < NCF 0.5/2. It is also observed that the dispersion on the surface of the activated carbon increases with the total number of accessible activated sites and decreases with the total number of sites in the sample.Le calcul théorique du nombre de sites actifs lors de l'adsorption de l'acide tartrique en solution par quatre échantillons de charbons actifs commerciaux (2SAP/C, COM3, NC 35 et NCF O.5/2) révèle que le nombre de sites actifs accessibles à la surface de ces charbons croît avec le pH. Il apparaît également que vis-à-vis de l'adsorption de l'acide tartrique, les charbons actifs basiques (NC 35 et NCF 0.5/2) ont plus de sites actifs que les charbons actifs acides (2SAP/C et COM 3). Les résultats obtenus, en accord avec ceux obtenus par exploitation des modèles de Freundlich et de Langmuir, montrent que le pouvoir adsorbant varie dans l'ordre 2 SAP/C < COM 3 < NC 35 < NCF 0.5/2. On démontre également que la dispersion à la surface des charbons actifs augmente avec le nombre de sites actifs et diminue avec la grosseur des particules de charbon

Intramolecular [3 + 2] Cycloaddition Reactions of Unsaturated Nitrile Oxides. A Study from the Perspective of Bond Evolution Theory (BET)

The reaction mechanism of the [3 + 2] intramolecular cycloaddition of 3,3-dimethyl-2-(prop-2-en-1-yloxy) and (prop-2-en-1-ylsulfanyl) nitrile oxides is analyzed using different DFT functionals with the 6-311++G­(d,p) basis set. The activation and the reaction energies for the cis and trans pathways are evaluated at the DFT, MP2, and CCSD­(T) levels of theory as well as their Gibbs free energy counterparts. It is shown that the trans regioisomers are both thermodynamic and kinetic compounds, in agreement with experimental outcomes. For a deeper understanding of the reaction mechanism, a BET analysis along the reaction channel (trans and cis) has been carried out. This analysis reveals that the lone pair on the nitrogen atom is formed first, then the C–C bond, and finally the O–C one. The global mechanism is similar for the two compounds and for the two pathways even if some small differences are observed, for instance, in the values of the reaction coordinates of appeareance of the different basins

Etude comparative de l’adsorption de l’acide 5-sulfosalicylique et des ions orthophosphates en solution aqueuse par des charbons actifs

A study was made of the adsorption of 5-sulfosalicylic acid and orthophosphate ions from aqueous solutions by two commercially activated carbons. Adsorption isotherms obtenained at 298°K were both of Langmuir and Freundlich types and from them adsorption capacities were calculated. From these results, the activated carbon with a pH=8 adsorbs both adsorbates better than the other one (pH=7) and the orthophosphate ions are better adsorbed than the 5-sulfosalicylic acid. These results are comfirmed from theoretical calculations of accessible number of active sites obtained for both the activated carbons. It has also been shown that the percentage dispersion of these active sites is high at the surface. Those results correspond with the number of active sites accessible at the surface.L’adsorption de l’acide 5-sulfosalicylique et des ions orthophosphates en solution aqueuse par deux charbons actifs commerciaux a été effectuée. Les isothermes d’adsorption de Langmuir et de Freundlich ont été obtenues à 298°K et le calcul des capacités d’adsorption montre que les ions orthophosphates sont mieux adsorbés que l’acide 5-sulfosalicylique et que les deux charbons ont des propriétés d’adsorption liées au nombre de sites actifs accessibles, c’est-à-dire présents à la surface des grains