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.
This study reports on the adsorption efficiency of a natural iron oxide from Mballam-Cameroon in comparison with synthesized goethite to simultaneously remove cobalt and nickel ions from aqueous solutions. Chemical analysis on the natural iron oxide sample revealed iron as the main element and hematite (58.52%) goethite (19.42%), kaolinite (12.69%) and quartz (7.79%) as the component phases in the iron oxide sample. The iron oxide was found to be microporous (BET surface area 43.27 m 2 /g) with fairly spherical polydisperse particles. Results show maximum absorption for Co(II) and Ni(II) ions for both adsorbents occurred at an equilibrium contact time of 80 mins, dose rate of 0.1 g/L, and pH = 7. Goethite was slightly more efficient at removing target metal ions with maximal adsorbed quantities at 117.8 mg/g of Co(II) and 100.6 mg/g of Ni(II), and 103.9 mg/g of Co(II) and 85.2 mg/g of Ni(II) ions for natural iron oxide. Equilibrium modelling presented the Freundlich isotherm as the best fit model for both adsorbents and metal ions, indicating heterogeneity of the surface binding sites during adsorption. The pseudo-second order kinetic model was the best-fit model, indicating chemical adsorption between the adsorbent surface and metal ions, hence a good correlation between equilibrium and kinetics. The findings indicate that the efficacy of the natural iron oxide from Mballam is almost equivalent to that of synthetic goethite, validating its applicability for the simultaneous removal of cobalt and nickel ions from aqueous solution.
This study focuses on the mineralogical, geochemical and petrographic characterization of three granite rock samples (LTP, LTS and LTMB) from Foumban, West Region of Cameroon. Fusibility tests were carried out on the samples containing the highest amount of alkali to assess the potential of these materials as fluxing admixture for ceramics. The results show that the granite consists of alkaline feldspars, notably orthoclase and microcline of perthitic micro-texture, plagioclases (in particular albite) and also mafic minerals such as amphibole and pyroxene. The quantity of alkali in the samples is quite high (16.83% for LTS, 17.08% for LTMB and 18.87% for LTP) compared to standard data. Fusibility tests carried out on the samples having the highest alkali content (LTMB and LTP) showed that the vitreous phase appears between 1050˚C and 1100˚C in these samples when they were heated. The Fe 2 O 3 and TiO 2 content of LTMB (3.01% and 1.49% respectively) led to a brown colour of its fired product. Therefore, based on their composition, these materials can be used as feldspathic fluxes for the formulation of ceramic products.
Abstract:This study investigates the adsorption efficiency of goethite nanostructured powder for the simultaneous removal of cobalt and nickel ions. The nanostructured powder sample was synthesized via a chemical precipitation technique and characterized using SEM, FTIR-ATR and XRD techniques. From batch adsorption studies, maximum absorption for Co(II) and Ni(II) ions occurred at an equilibrium contact time of 80 min, with an adsorbent mass of 0.1 g, and at pH=7. Co(II) ions showed greater affinity to the nanoparticles as compared to Ni(II). The maximum quantities adsorbed were recorded as 148.5 mg/g for Co(II) and 110.6 mg/g for Ni(II) ions. The best isotherm model fit for both metal ions was the Freundlich model indicating heterogeneity of the surface binding sites. The pseudo-second order kinetic model was the best-fit model: an indication of a strong chemical adsorption between the adsorbent surface and metal ions. The findings show that the goethite nanostructured powder is a very effective adsorbent material and prominent candidate for the simultaneous removal of cobalt and nickel ions from water.
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