Decolourization of melanoidin containing wastewater using South African coal fly ash

Vincent O Ojijo, Maurice S. Onyango, Aoyi Ochieng, Fred Otieno

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Batch adsorption of recalcitrant melanoidin using the abundantly available coal fly ash was carried out. It had low specific surface area (SBET) of 1.7287 m²/g and pore volume of 0.002245cm³/g while qualitative evaluation of the predominant phases in it was done by XRD analysis. Colour removal efficiency was found to be dependent on various factors studied. Maximum colour removal
was achieved around pH 6, whereas increasing sorbent mass from
10g/L to 200 g/L enhanced colour reduction from 25% to 86% at 298
K. Spontaneity of the process was suggested by negative Gibbs free
energy while positive values for enthalpy change showed endothermic nature of the process. Non-linear optimization of error
functions resulted in Freundlich and Redlich-Peterson isotherms describing sorption equilibrium data best. The coal fly ash had
maximum sorption capacity of 53 mg/g and could thus be used as a
low cost adsorbent in melanoidin removal.
Original languageEnglish
Pages (from-to)17-23
Number of pages7
JournalInternational Journal of Civil and Environmental Engineering
Issue number1
Publication statusPublished - 2010


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