Carbon dioxide absorption in a gas-liquid membrane contactor: Influence of membrane properties and absorbent chemistry

The present work demonstrates the performance of hollow fibre membranes fabricated using polyvinyl chloride, polystyrene (EPS) and polydimethylsiloxane (PDMS) coupled with 30% monoethanolamine (MEA) in a gas liquid membrane contactor (GLMC) for the absorption of carbon dioxide. A gas mixture with a composition of (50/50 v/v%) methane (CH4) and (CO2) was used to assess the efficiency of the prepared membranes in the removal of carbon dioxide. Then HFM 3 which showed high CO2 removal was used to separate a mixture of nitrogen (N2)/oxygen(O2)/carbon dioxide (CO2) with a composition of (73/18/9 v/v%), respectively. Four different absorption liquids: 30 % MEA solution, 30 % EDA solution, 30 % MEA – graphene oxide (GO) and 30 % EDA-GO nanofluids were coupled with HFM3 to analyse the efficiency of the different amine liquids in CO2 absorption in GLMC. The 30 % EDA-GO solution showed an increase in the efficiency of CO2 absorption. The nanofluids showed an enhancement factor for CO2 absorption in the nanofluid was 121 % and 117 % for MEA-GO and EDA-GO, respectively. This enhancement was attributed to the hydrodynamic effects and Brownian motion of graphene oxide in the amine liquids. 30 % EDA solution infused with 0.2 mg/ml graphene oxide nanoparticles achieved the highest loading of carbon dioxide 0.25 mol/ cm3

Quantitative analysis of phenols and PAHs in the Nandoni Dam in Limpopo Province, South Africa : a preliminary study for dam water quality management

This paper assesses the level of phenols and polycyclic aromatic hydrocarbons (PAHs) in the Nandoni dam situated in the Vhembe District, Limpopo Province, South Africa. About 55 villages are supplied with water sourced from the dam which is prone to contamination by different pollutants other than phenols and PAHs, due to its exposure to agricultural, human and animal activities around it. A quantitative determination of these pollutants was conducted using a gas chromatography-time-of-flight mass spectrometer (GC-TOF MS) after sample preparation that involved solid phase extraction (SPE). Water samples were collected on a seasonal basis in spring, summer, autumn, and winter. Several phenolic compounds (phenol, 2-chlorophenol, 2,6-dichlorophenol, 2,4,5-trichlorophenol, 2,4-dimethylphenol, 4-nitrophenol and p-cresol) were detected in the dam at concentration levels not suitable for drinking purposes. The recorded concentrations were generally higher than the SANS 241, US EPA and WHO acceptable limits in drinking water with up to 1.11 mg/L recorded for 2,4,5-trichlorophenol. The concentrations of PAHs (naphthalene, acenaphthene, pyrene, benz(a)anthracene and benzo(a)pyrene) fell within the threshold limits and were typically less than 0.1 mu g/L. The water treatment plants sourcing water from the Nandoni dam use conventional treatment processes that focus more on removing contaminants such as microorganisms and heavy metals without considering the danger of long-term effects of organic contaminants, whose harmful health effects are observed after long periods of exposure. Therefore, this dam requires coordinated management of the water resources in order to maximize the economic and social welfare equitably without affecting human life and the ecosystem