Earth Sciences

Permanent URI for this community

http://192.168.18.118:4000/handle/20.500.12661/11

Browse

Browsing Earth Sciences by Subject "Activated carbon"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Defluoridation of water supplies using coconut shells activated carbon: batch studies
    (International Journal Of Science And Research (IJSR), 2014) Said, Mateso; Machunda, Revocatus L.
    Drinking water with elevated fluoride levels results in serious irreparable health problem that has attained an alarming dimension all over the world, Tanzania being one of the affected countries; techniques have been under study for years. Batch experiments were carried out to determine the effect of various adsorbent factors such as adsorbent dose, initial pH, particle size and contact time on adsorption process. Adsorption efficiency was observed to increase with decrease in particle size, the highest efficiency recorded was 68.2 and 65.9% for field and synthetic water respectively when particle size less than 150µ of coconut shells activated carbon were used. Adsorption was observed to be favoured by pH in acidic range and the maximum efficiency of 58.4% was recorded at pH of 2.0 and particle sizes between 4.18-2.36mm. The pH of the effluent was lowered to acidic range which necessitates further treatment of the effluent or coupling with other materials for pH elevation before use. Adsorption increases with adsorbent dose hence at a smaller influent concentration; the required standard of 1.5mg-F- /l can be met. Equilibrium isotherms have been analysed using Langmuir and Freundlich isotherm models, and both of the models fit to explain the adsorption behaviour of fluoride ions onto Coconut shell activated carbons, during this study it was established that when properly activated; coconut shells can be appropriate for use household filters that could be cost effective in rural areas of Tanzania due its local availability and its colour adsorption property
  • Thumbnail Image
    Item
    Molecular simulation of benzene adsorption on different activated carbon under different temperatures
    (ELSEVIER, 2020) Li, S.; Song, K.; Zhao, D.; Rugarabamu, J. R.; Diao, R.; Gu, Y.
    Four different structure models of activated carbon were constructed here by molecular simulation method. The four models include three Detecting community structure via the maximal sub-graphs and belonging degrees in complex networks with micropore sizes of 9–11 Å, 10–12 Å, and 13–16 Å, respectively, and one microporous-mesoporous structure with pore sizes of 15–17 Å and 21–24 Å. The microporous-mesoporous structure was easily adjusted by the introduction and deletion of single-wall carbon nanotubes (SWCNTs, 15, 15). The adsorption of benzene on different structure models at temperatures of 273.15, 288.15, 303.15 and 318.15 K were studied by Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) methods. Adsorption isotherms, average isosteric heats of benzene adsorption, porosity and pore volume change after benzene adsorption at different temperatures were analyzed. The radial distribution function, relative concentration distributions and diffusion coefficients of benzene molecules on different structure models were further studied. Comprehensive analysis results indicate that for low temperature, activated carbon with larger micropores and mesopores is favorable to adsorption of benzene. But for high temperature, activated carbon with smaller micropores is favorable to adsorption of benzene.
  • Thumbnail Image
    Item
    Study on co-adsorption mechanisms of benzene and toluene on activated carbon via molecular simulation
    (Elsevier, 2020) Li, S.; Song, K.; Yu, L.; Rugarabamu, J. R.; Zhao, D.; Diao, R.
    In this paper, four-type activated carbon (AC) models are constructed and the co-adsorption processes of benzene and toluene on models under 303.15 K are studied by molecular simulation. The microscopic mechanisms in adsorption process including isotherms, energy changes, adsorption sites, and diffusion coefficients were discussed. The results indicate the small micropores less than 13 Å and larger micropores, smaller mesopores from 13 Å to 24 Å are favorable for benzene adsorption and toluene adsorption, respectively. Moreover, the adsorption amounts increase with the increase of oxidation degree in AC structure.