Diploma Thesis Defense by Mrs. Boulougari Aggeliki
Thesis Title: «Production of KMnO4 amended biochar for the removal of Ni(II) and As(V) from aqueous Thursday 20 February 2020, at: 11:00, Venue: Hall : Κ2.Α3
- Professor Evan Diamadopoulos (advisor)
- Professor Konstantinos Komnitsas
- Assistant Professor Nikolaos Xekoukoulotakis
Τhe main aim of this study is the removal of Ni (II) and As (V) from aqueous solution on modified with KMnO4 biochar derived by pyrolysis of two different types of biomass: Sludge and rice husks. Pyrolysis of the above biomass samples (unmodified, as well as modified) took place at two temperatures, 400°C and 600°C, resulting in eight biochars. The biomass and the biochars obtained were characterized for their elemental composition, ash, volatile solids, pH and electric conductivity, while for the biochars the zero charge point was further determined. These analyses, along with the yield of pyrolysis, have shown that optimal biochars, on the basis of their physicochemical properties, were those obtained from sludge, whether modified or not, at pyrolysis temperature 400°C.
Following the characterization of the materials, then adsorption experiments were conducted for all biochars. In the adsorption experiments, the removal efficiency of three parameters on the adsorption of Ni (II) and As (V) was investigated, namely the dose of each adsorbent, the pH of the solution and the contact time. Based on the results, all biochars showed high adsorption capacity towards Ni2+, while the corresponding adsorption capacity towards As5+ was much smaller. In both cases, however, the modification did not bring about the desired increase in the removal efficiency, as the unmodified biochars showed metal removal rates up to 98% for Ni2+ and 35% for As5+. On the other hand, the removal of KMnO4-modified biochars was at the same level as the unmodified biochar. Regarding the adsorption time, the maximum adsorption of Ni (II) was achieved in less than half an hour, while the equivalent one of As (V) in half an hour. Therefore, based on the results we conclude that the amendment did not result in significant changes in the removal of the two metals.