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-H3PO4of 52.10%, theI2/AC-H3PO4of 697.86 mg/g, and the MB/AC-H3PO4of 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.

The uptake of tartrazine from its aqueous solution by powdered activated carbon prepared from cola nut shells chemically activated with potassium hydroxide (ACK) and phosphoric acid (ACP) has been investigated using kinetics models. Batch isotherm data were analysed with the pseudo-first order, pseudo-second order model as well as the intraparticle diffusion model. For structural elucidation, the materials were characterized using FTIR, XRD and SEM. These analyses revealed that the activated carbons (ACK and ACP) were predominantly mesoporous with several oxygen-containing functional groups dispersed on their surface. The reaction was systematically investigated under various experimental conditions such as contact time, adsorbent dose and pH. For the two adsorbents, the quantity adsorbed of 19.256 mg/g and 18.196 mg/g respectively for ACP and ACK at respective contact times of 5 and 10 min were obtained. The adsorption data were tested with the Langmuir, Freundlich models. Langmuir model was found to best describe the adsorption of tartrate ions with maximum monolayer adsorption capacities of 24.57 and 21.59 mg/g for ACP and ACK, respectively. Results analysis indicated clearly that the pseudo-second order kinetic rate model best fitted the experimental data and therefore was the adsorption controlling mechanism for both adsorbents. Thermodynamic studies revealed that the adsorption process was spontaneous and exothermic for ACP with increased randomness at the solid solution interface, then exothermic but non-spontaneous for ACK. The results show that these activated carbons could be an alternative for more costly adsorbents for the purpose of tartrate ions elimination.

Egusi seed shells (ESS) were used as precursor for the preparation of two activated carbons (ACs) following H 3 PO 4 and ZnCl 2 activation. The effect of factors controlling the preparation of ACs such as chemical activating agent concentration (2-10 M), activation temperature (400˚C-700˚C) and residence time (30-120 min) were optimized using the Box-Behnken Design (BBD). The optimized activated carbons based H 3 PO 4 (ACP) and ZnCl 2 (ACZ) were characterized by N 2 adsorption, elemental analysis, atomic force microscopy (AFM), Boehm titration and Fourier transformed infrared (FTIR) techniques. The specific surface area was found to be 1053.91 and 1009.89 m 2 •g −1 for ACP and ACZ respectively. The adsorbents had similar surface functionalities and were both microporous. The effect of various parameters such as initial pH, concentration, and contact time on the adsorption of nitrate ions on ACP and ACZ in aqueous solution was studied. ACZ demonstrated better adsorption capacity (8.26 mg•g −1) compared to ACP (5.65 mg•g −1) at the same equilibrium time of 20 min. The adsorption process was governed by a "physical interactions" phenomenon for both adsorbents.

Activated carbon based oil palm shells were prepared by physical activation using steam which was further grafted with silver. The Response Surface Methodology (Doehlert design) was used to optimize both the impregnation of silver and the atrazine removal. The effects of three variables of preparation conditions of the composite activated Carbon-Silver (AC-Ag): Concentration of silver, impregnation temperature and impregnation time on the atrazine removal (Y 1 ) was investigated on one hand. In another hand, three variables of atrazine removal from liquid phase: Temperature, pH and ratio of Atrazine/CaCl 2 (r(Atraz/CaCl 2 )) on the adsorption capacity of atrazine (Y 2 ) were also investigated. Based on the Doehlert designs, the quadratic models were developed to correlate the preparation variables and the adsorption variables to the response. The optimum conditions of preparation of AC-Ag were found to be: Concentration of silver of 0.063 mol/L, impregnation temperature of 223˚C, impregnation time of 1.3 hand atrazine removal of 384.62 mg/g. The optimum conditions of atrazine adsorption were found to be: Temperature of 25.0˚C, pH of 7.7 and r(Atraz/CaCl 2 ) of 0.37 which gave 209 mg/g of atrazine adsorption capacity. These results demonstrated that the preparation and adsorption conditions have a significant influence on the removal of atrazine.

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This study aims to identify the influence of soil organic matter (OM) content and calcium carbonates (CaCO3) on soil reflectance and select the optimum spectral bands for discriminating between topsoils of different soil types situated in the irrigated perimeter of the Triffa plain (Morocco) using VIS-NIR reflectance spectroscopy. Soil samples were collected from the plow layer in 26 sampling sites. The spectral measurements were conducted in the field using an ASD Fieldspec portable spectroradiometer (350–2500 nm), while the soil samples were analyzed in the laboratory. The spectral data were pre-processed to remove the noise effects and then analyzed with the CovSel (selected covariance) method, validated by linear discriminant analysis in order to select the most optimal spectral variables to discriminate between topsoils of different soil types in the plain. The results of the soils reflectance curves showed that low reflectance intensity marked the soils with high OM contents throughout the VIS spectrum. The influence of the soil OM content was very apparent in the VIS range (between 580–750 nm). Regarding the CaCO3 content, it was noted that the soil samples with a high percentage of CaCO3 increase the reflectance in all spectral domains situated between 350 and 2500 nm. The spectral bands of 1999, 686, 1280, 2340 and 1951 nm were the most optimal for the soil discrimination in the Triffa plain. This study concluded that the VIS-NIR spectroscopy demonstrates an excellent ability to characterize and discriminate between topsoils in the Triffa plain.

<p>The adsorption of Cu2+ions on activated carbon based canarium schweinfurthii impregnated with ZnCl2 was studied. The shells of canarium schweinfurthii were impregnated with ZnCl2 at varying ZnCl2 concentrations, temperature, residence time while keeping the heating rate fixed at 10 °C / min and the ratio of impregnation of 1:1. The activated carbon with the highest surface area in term of iodine number of 860,817 mg/g, the highest methylene blue of 741,6 mg/g and 74,66 % of yield of carbon was obtained at 650 °C, 60 % ZnCl 2 and 30min. From the batch adsorption studies, the equilibrium time was found to be 40 min. Analysis of equilibrium isotherm models revealed a good correlation of the experimental data with the Tempkin (R 2 = 0.909) model. This confirms a high affinity of the activated carbon for Cu 2+ ions on the heterogeneous surface. The value of energy obtained from the Tempkin model was 60,606 J/mol and the presence of pics between 487 cm-1 to 871 cm-1 indicating that physisorption and chemisorption were taking place during this sorption. The pseudo-second order kinetics(R 2 = 0.999) governs the adsorption of Cu2+ions on this activated carbon.</p>

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