Carbon dioxide removal by adsorption

Carbon dioxide (CO2) among other air pollutants is a major culprit to the greenhouse gases that is fueling global warming. To mitigate global warming, Kyoto Protocal urges 37 industrialized nations and European Union to reduce their greenhouse gas emissions to a level of 5.2% on average lower than those of 1990 during the period of 2008-2012. It is therefore essential to develop the CCS technologies to cope with the global demand of CO2 reduction. In this study the technologies of CO2 removal are reviewed

Optimization and activation of renewable durian husk for biosorption of lead (II) from a aqueous medium

Background: Biosorption of lead Pb(II) by durian husk activated carbon (DHAC) was investigated. The main aim of this work is to explore the effect of operating variables such as pH, biosorbent dose, temperature, initial metal ion concentration and contact time on the removal of Pb(II) from synthesized aqueous medium using a response surface methodology (RSM) technique. The experimentation was performed in two sets, namely set 1 and set 2. Results: For experimental set 1, pH was set to 7.0. The optimum conditions for the remaining parameters were determined to be 0.39 g DHAC dose, 60 min contact time and 100 mg L−1 of initial metal ion concentration, which yielded maximum biosorption capacity of 14.6 mg g−1. For experimental set 2, 41.27 °C, 8.95 and 99.96 mg L−1 were the optimum conditions determined for temperature, pH and initial Pb(II) concentration, respectively; which revealed a maximum adsorption capacity of 9.67 mg g−1. Characterization of the adsorbent revealed active functional groups such as hydroxyl, carboxylic, alcohol and hemicellulose. The equilibrium adsorption data obeyed the Langmuir isotherm and pseudo‐second‐order kinetic models with maximum Langmuir uptake of 36.1 mg g−1. Conclusions: The biosorbent was capable of reuse, so that the abundant durian husk could be utilized effectively for the removal of Pb(II) from polluted water

Effect of membrane on carbonation and carbon dioxide uptake of

Recent studies showed that as low as 5% CO2 increased microalgae growth. However, common bioreactor operation resulted in low carbonation due to poor CO2 mass transfer and this inhibited CO2 uptake of microalgae. Although bubbling increases mass transfer of CO2-O2 exchange, preserving high dissolved CO2 remains the most challenging of microalgae cultivation in bioreactor. In order to increase high dissolved CO2 and CO2-O2 exchange, this study employed two types of membrane; hollow-fibre membrane for carbonation and hydrophobic membrane for deoxygenation. It was found that membrane increased carbonation from 20 % to 75 % when operated at control CO2 concentration. The hollow-fibre membrane capable of creating as small as 2 mm bubble which effective for high carbonation. At the same time, itincreased CO2 uptake up to 85% in bioreactor. The hydrophobic membrane removed 43% O2 from the bioreactor. Both membranes increased mass transfer of CO2-O2 exchange in bioreactor which stimulated microalgae growth

Adsorption Performance and Evaluation of Activated Carbon from Coconut Shell for the Removal of Chlorinated Phenols in Aqueous Medium

In this study, the removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions was performed using coconut shell activated carbon prepared by a two-stage self-generated atmosphere method. Coconut shell was first semi-carbonized at 300 °C for an hour followed by chemical activation with zinc chloride (ZnCl2) as activating agent at 500 °C for 2 h. The effect of impregnation ratio on the physical and chemical properties of activated carbons (ACs) was studied. The morphology and surface chemistry of the prepared carbons were characterized using Scanning Electron Microscope (SEM) and Fourier Transform Infrared spectroscopy (FTIR) respectively. The percentage of yield for the prepared AC was found to be in the range of 26.40 – 38.82 %. AC registered the highest adsorption capacity and was used in subsequent batch adsorption studies consisting of parameters such as initial concentration, adsorbent dosage and solution pH. The maximum surface area of the best produced AC was recorded as 1482 m2 g-1. The adsorption capacity was found to increase in proportional to the initial concentration and adsorbent dosage, while acidic solution pH was more favourable for the adsorption of 2,4-DCP by the prepared AC. The equilibrium time for the adsorption of 20 mg L-1 of 2,4-DCP on 0.5 g of AC was achieved in 180 min. Adsorption isotherms such as Langmuir, Freundlich and Temkin isotherm models were employed to examine the experimental isotherms while the reaction kinetic data was analysed using pseudo-first-order, pseudo-second-order and intraparticle diffusion model. The 2,4-DCP adsorption results fitted best in the Freundlich isotherm as indicated by the high correlation coefficient value (R2 &gt; 0.9949) while the adsorption kinetic fitted to the pseudo second-order model (R2 &gt; 0.9621).DOI: http://dx.doi.org/10.5755/j01.ms.23.4.16221</p