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- South African Journal of Chemical Engineering
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- Volume 19, Issue 1, 2014
South African Journal of Chemical Engineering - Volume 19, Issue 1, 2014
Volume 19, Issue 1, 2014
Modified coconut fiber used as adsorbent for the removal of 2-chlorophenol and 2, 4, 6-trichlorophenol from aqueous solutionSource: South African Journal of Chemical Engineering 19, pp 1 –21 (2014)More Less
The aim of this work was to determine the potential application of adsorbent prepared from coconut fiber for the removal of organic water pollutants. Removal of 2-chlorophenol (2-CP) and 2, 4, 6-trichlorophenol (TCP) from aqueous solution by coconut fiber activated carbon (FAC) and acid treated coconut fiber activated carbon (ATFAC) was investigated. Equilibrium and kinetic studies were performed and the data was fitted to isotherm and kinetic models. Langmuir isotherm model fitted better than Freundlich to the adsorption data. The monolayer adsorption capacity of ATFAC (38.29 mg g-1 for 2-CP and 101 mg g-1 for TCP) at 25°C was relatively higher as compared to that of FAC (37.11 mg g-1 for 2-CP and 49.80 mg g-1 for TCP). The adsorption trend was as follows: ATFAC (TCP) > ATFAC (2-CP) > FAC (TCP) > FAC (2-CP). The pseudo-second-order rate model fitted better to the adsorption kinetics as compared to the pseudo-first-order rate model in all the cases. Overall adsorption rate is controlled by film diffusion. The thermodynamic parameters (free energy, enthalpy, entropy changes) exhibited the feasibility and spontaneous nature of the adsorption process. The results of the study show that the carbon prepared from acid treated coconut fiber is more effective than thermally treated fiber in the removal of chloro phenols and can be used as a potential adsorbent for the removal of water pollutants.
Source: South African Journal of Chemical Engineering 19, pp 22 –30 (2014)More Less
This study investigates the reduction of sulphur compounds in crude tyre pyrolysis oil through gas-phase adsorption over molecular sieve. Crude tyre pyrolysis oil was distilled at 300° C using a bench scale distillation set-up consisting of an electric heating mantle, glass round bottom flask and water cooled glass condenser. The glass condenser bulb was filled with steel wool and molecular sieve pellets for effective oxidation and adsorption of sulphur compounds in the vapours prior to condensation. It was observed that gas-phase adsorption improves total sulphur capture by 19.6%. Reduction in sharp pungent smell of the condensed distilled light fractions is justified by 21.7% total sulphur removal of low boiling point mercaptans and sulphides during moisture removal stage. High boiling point and large molecular size sulphur compounds in the distilled fractions can be further reduced by 3.6% using liquid phase adsorption over activated carbon black.
Heterogeneous photocatalytic degradation of naphthalene using periwinkle shell ash : effect of operating variables, kinetic and isotherm studySource: South African Journal of Chemical Engineering 19, pp 31 –45 (2014)More Less
This study investigated the potential use of low cost photocatalyst, Periwinkle shell ash (PSA) for the batch photocatalytic degradation of naphthalene in aqueous solutions. The effect of contact time, initial naphthalene concentration, PSA dosage, presence of electron accepting oxidant (H2O2), and the pH of solution on the percentage photodegradation of naphthalene determined. For the treatment conditions considered in this study, the optimum values were obtained to be: contact time, 210 minutes; initial naphthalene concentration, 25 mg/L; PSA dosage, 2 g; pH, 9. The addition of Hydrogen Peroxide (H2O2) enhanced the photodegradation process with almost 100 percent degradation achieved. The adsorption equilibrium data fitted well to the Langmuir isotherm equation (R2=0.993) indicating mono layer type adsorption while the kinetics of the process was well described by the Langmuir-Hinshelwood kinetic model with high correlation coefficient value (R2=0.998). This study has demonstrated that the low cost photocatalyst, PSA can be used for removal of naphthalene from aqueous solution. Also the kinetic information obtained can be used for designing treatment systems for naphthalene abatement.
Saccharification of bamboo by dilute acid pretreatment and enzymatic hydrolysis for cellulosic ethanol productionSource: South African Journal of Chemical Engineering 19, pp 46 –52 (2014)More Less
In this research, dilute sulphuric acid pretreatment for enzyme saccharification using herbaceous lignocellulose, giant bamboo, was investigated for the purpose of studying its potential as feedstock for ethanol production. Bamboos are giant woody, tree-like, perennial evergreen C4 grasses with more than 70 genera and about 1000 species. Bamboos grow naturally in tropical, subtropical, and temperate regions around the world. The central composition design was employed to optimize the pretreatment parameters, pretreated temperature range from 178 to 205 °C, residence time range from 1 to 15 minutes and acid concentration range from 0.14 to 0.44 g/ 100 g material, at reactor loading of 30%w/v (solid weight/liquid volume) in the small scale tubular reactors. The pretreated solids were enzymatically hydrolysed using enzyme loading 15 FPU/g WIS (water insoluble solid) at 50 °C for 72 h. Up to 50% glucose and 83% xylose were released from bamboo by pretreatment and enzymatic hydrolysis.