Faculty of Agriculture and Environment

Permanent URI for this community

http://localhost:4000/handle/20.500.14270/1

Browse

Browsing Faculty of Agriculture and Environment by Subject "Activated carbon"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Synthesis and Application of Granular Activated Carbon from Biomass Waste Materials for Water Treatment :
    (Keai publishing, 2021-04-06) Jjagwe, Joseph; Olupot, Peter Wilberforce; Menya, Emmanuel; Mpagi Kalibbala, Herbert
    There is an increased global demand for activated carbon (AC) in the application of water treatment and purification. Water pollutants that have exhibited a greater removal efficiency by AC included but are not limited to heavy metals, pharmaceuticals, pesticides, natural organic matter, disinfection by-products, and microplastics. Granular activated carbon (GAC) is mostly used in aqueous solutions and adsorption columns for water treatment. Commercial AC is not only costly but also obtained from non-renewable sources. This has prompted the search for alternative renewable materials for AC production. Biomass wastes present a great potential for such materials because of their availability and carbonaceous nature. This, in turn, can reduce the adverse environmental effects caused by poor disposal of these wastes. The challenges associated with biomass waste-based GAC are their low strength and attrition resistance which make them easily disintegrate under the aqueous phase. This paper provides a comprehensive review of recent advances in the production of biomass waste-based GAC for water treatment and highlights future research directions. Production parameters such as granulation conditions, use of binders, carbonization, activation methods and their effect on textural properties are discussed. Factors influencing the adsorption capacities of the derived GACs, adsorption models, adsorption mechanisms, and their regeneration potentials are reviewed. The literature reveals that biomass waste materials can produce GAC for use in water treatment with the possibility of being regenerated. Nonetheless, there is a need to explore 1) the effect of preparation pathways on the adsorptive properties of biomass-derived GAC, 2) sustainable production of biomass-derived GAC based on life cycle assessment and techno-economic analysis, and 3) adsorption mechanisms of GAC for removal of contaminants of emerging concerns such as microplastics and unregulated disinfection by-products.
  • Thumbnail Image
    Item
    Synthesis and evaluation of activated carbon from rice husks for removal of humic acid from water
    (Springer, 2020-11-26) Menya, E.; Olupot, P. W.; Storz, H.; Lubwama, M.; Kiros, Y.
    Activated carbon was synthesized from the New Rice for Africa (NERICA) rice husk variety, followed by its evaluation for removal of humic acid from water. Product values of carbon yield, C and total specific surface area, as,BET were employed as the performance criterion. The best physically activated carbon resulted from char activation at 800 °C for 10 min, leading to as,BET and C×as,BET values of 756.8 and 402.7 m2 g−1, respectively. The best chemically activated carbon resulted from 30 wt% H3PO4 activation of rice husk at 400 °C for 30 min, leading to as,BET and C×as,BET values of 2258.4 and 1058.7 m2 g−1, respectively. Despite the higher as,BET value, the maximum adsorption capacity of the best chemically activated carbon (5.3 mg g−1) was found lower than 8.9 and 27.2 mg g−1 exhibited by the chemically activated carbons prepared at 500 and 600 °C, respectively. The best adsorption conditions included carbon dose of 0.5 g, solution pH of 2, and contact time of 60 min. The adsorption capacity of the prepared activated carbons (27.2 mg g−1) was comparable to that of the commercial activated carbon (30.40 mg g−1). The analyses of the adsorption isotherms and kinetics revealed that the experimental data fits well the Langmuir isotherm model, as well as the pseudo-second-order kinetic model. The latter suggests that the adsorption of humic acid onto the activated carbon was controlled by the chemisorption process. Overall, the study revealed that the NERICA rice husk variety has good prospects for preparation of activated carbons for humic acid adsorption.