Cellulose II nanowhiskers (CNW-II) were produced by treatment of microcrystalline cellulose with sulfuric acid by both controlling the amount of H(2)SO(4) introduced and the time of addition during the hydrolysis process. The crystalline structure was confirmed by both XRD and (13)C CP-MAS NMR spectroscopy. When observed between crossed polarizers, the cellulose II suspension displayed flow birefringence and was stable for several months. The CNW-II nanowhiskers were significantly smaller than the cellulose I nanowhiskers (CNW-I) and had a rounded shape at the tip. The CNW-II average length and height were estimated by AFM to be 153 ± 66 and 4.2 ± 1.5 nm, respectively. An average width of 6.3 ± 1.7 nm was found by TEM, suggesting a ribbon-shape morphology for these whiskers. The average dimensions of the CNW-II elementary crystallites were estimated from the XRD data, using Scherrer's equation. A tentative cross-sectional geometry consistent with both XRD and NMR data was then proposed and compared with the geometry of the CNW-I nanowhiskers.

This study focused on the preparation of activated carbon modified with manganese oxides, in order to apply it to the removal of methylene blue in aqueous solution. Activated carbon (AC) was elaborated from cocoa pod shells, which is a local biomass available in Côte d'Ivoire. This activated carbon was then modified with manganese oxides to give AC-MnO2 in order to increase its performance in the removal of methylene blue in aqueous solution. The characterization of these activated carbons revealed their microporous structure with a specific surface of 890.64 m2/g for AC and 732.3 m2/g for AC-MnO2. Kinetic study showed that the methylene blue elimination reaction is pseudo-second order with an equilibrium time of 60 min. Langmuir's model of a monolayer adsorption better reproduces the experimental adsorption isotherms with a maximum adsorption capacity of 222.22 mg/g with CA and 270.27 mg/g with AC-MnO2. Keywords: Adsorption, Activated carbon, cocoa pod shell, Methylene blue, manganese oxides

No abstract

40www.ijeas.org  Abstract-To eliminate pollutants efficiently and at a lower cost, research is focused on the use of agricultural waste as a pollution control material. This work involves the analysis of the physical and chemical parameters of raw carbon from cocoa pod shells. The cocoa shells were crushed using Retsch SK100 brand shredders and sieved from Retsch type sieves to retain only particles with diameters between 0.5mm and 1mm. Pyrolysis was carried out at 400°, 450°, 500° and 550°C in a Nabatherm 30-3300°C muffle furnace. Analysis of the results indicates pyrolysis yields of less than 50% and ash rates varying from 15% to 17.2%. The porosity study showed that carbons developed a heterogeneous porosity with maximum iodine and methylene blue index values equal to 659mg/g and 104.56mg/g respectively and a specific area varying from 427.75m²/g to 588.25m²/g. These physical characteristics allowed to determine the best raw carbons. The modeling of the basic and acid dye adsorption kinetics follows the intra-particle diffusion model. The equilibrium time obtained is 60min.

The aim of this research is to investigate the feasibility of using activated carbon from cocoa pod shells, waste from agriculture to adsorb methylene blue from aqueous solutions through batch tests. Various physiochemical parameters such as, contact time, initial dye concentration, adsorbent dosage, pH of dye solution and temperature were investigated in a batch-adsorption technique. The process followed the pseudo-second order kinetics model which showed chemical adsorption. Langmuir and Freundlich isotherm models were used to determine adsorption constants. The maximum adsorption capacity at 30°C is 526.31 mg/g. Thermodynamic parameters such as enthalpy change (∆Hº), free energy change (∆Gº) and entropy change (∆Sº) were studied, and the adsorption process of BM was found to be exothermic and spontaneous.