Authors :
M. Clotilde Apua
Volume/Issue :
Volume 6 - 2021, Issue 11 - November
Google Scholar :
http://bitly.ws/gu88
Scribd :
https://bit.ly/3xYzNaN
Abstract :
Coal fly ash (CFA) sample produced in coalburning power plants contains significant quantities of
oxides of aluminium, iron and other important elements
such as magnesium, silicon and calcium for the production
of coagulant for wastewater treatment. In order to
synthesize a coagulant, the dissolution of these CFA
elements was studied in sulphuric acid (H2SO4) solutions.
The impacts of dissolution time, H2SO4 concentration,
temperature and solid/liquid ratio were investigated for
the leaching process. The treated CFA samples were
characterized by PSD, XRD, XRF, FTIR and SEM.
Thermodynamic feasibility was studied using
Hydra/Medusa software. The dissolution efficiencies of
aluminium, iron, magnesium, silicon and calcium were
33.86, 57.90, 73.21, 11.12 and 25.43%, respectively, in 1.5
M H2SO4, with a pH ranging from 0.5 to 3.9, at 300 rpm,
150 °C, a solid/liquid ratio of 0.20 and a leaching time of 6
hours. The PSD results revealed that particle size changes
happened during the leaching process, XRD and FTIR
showed the presence of the same mineral phases in the raw
and treated CFA samples, and SEM indicated that both a
porous structure and a stem-like structure were formed
after leaching. The generated dissolution solution
containing polymeric sulphates of aluminium, iron,
magnesium, silicon and calcium can be utilized as
coagulant in the treatment of wastewater. The process can
be easily adopted to synthesize complex coagulant,
therefore decreasing CFA pollution and producing a
valuable coagulant.
Keywords :
Synthesis; Pressure sulphuric acid-leaching; Coal fly ash; Coagulant; Wastewater
Coal fly ash (CFA) sample produced in coalburning power plants contains significant quantities of
oxides of aluminium, iron and other important elements
such as magnesium, silicon and calcium for the production
of coagulant for wastewater treatment. In order to
synthesize a coagulant, the dissolution of these CFA
elements was studied in sulphuric acid (H2SO4) solutions.
The impacts of dissolution time, H2SO4 concentration,
temperature and solid/liquid ratio were investigated for
the leaching process. The treated CFA samples were
characterized by PSD, XRD, XRF, FTIR and SEM.
Thermodynamic feasibility was studied using
Hydra/Medusa software. The dissolution efficiencies of
aluminium, iron, magnesium, silicon and calcium were
33.86, 57.90, 73.21, 11.12 and 25.43%, respectively, in 1.5
M H2SO4, with a pH ranging from 0.5 to 3.9, at 300 rpm,
150 °C, a solid/liquid ratio of 0.20 and a leaching time of 6
hours. The PSD results revealed that particle size changes
happened during the leaching process, XRD and FTIR
showed the presence of the same mineral phases in the raw
and treated CFA samples, and SEM indicated that both a
porous structure and a stem-like structure were formed
after leaching. The generated dissolution solution
containing polymeric sulphates of aluminium, iron,
magnesium, silicon and calcium can be utilized as
coagulant in the treatment of wastewater. The process can
be easily adopted to synthesize complex coagulant,
therefore decreasing CFA pollution and producing a
valuable coagulant.
Keywords :
Synthesis; Pressure sulphuric acid-leaching; Coal fly ash; Coagulant; Wastewater
