Dina David Joh Daniel

University of Douala, Cameroon

Title: Synthesis of pozzolan-lignin geopolymer composite and regeneration of industrial used activated carbon for the elimination of methyl orange in an aqueous medium

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Biography

DINA David JOH Daniel, born on the 7th September 1974 at Douala (Cameroon), Lecturer at the University of Douala since November 2002. Actually, Associate Professor in Department of Chemistry of the Faculty of Sciences of the University of Douala, specialty Inorganic Chemistry and Physical chemistry. Head of Chemistry Laboratory of the University of Douala and author of many publications.

Abstract

Pozzolan-lignin geopolymer composites and used activated carbons were respectively synthesized and regenerated, characterized for the removal of methyl orange in aqueous media. After lignin extraction from Bubinga (Guibourtia tessmanii) sawdust by the Organosolv process, geopolymer composites were synthetised by substitutinlv process, geopolymer composites were synthesized by substituting 5 and 10% pozzolan with thermally treated and untreated lignin. The used activated carbons were regenerated chemically and physically. The different materials were characterized by several techniques, including: X-ray Diffraction, Thermogravimetric analysis, Fourier Transform Infrared, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy, BET analysis and determination of iodine and methylene blue indices. For lignin, FTIR showed the presence of syringyl and guaiacyl units, and XRD an amorphous structure. XRD showed that the incorporation of lignin into the geopolymer matrix did not bring any new crystalline phase, however the iodine index values were improved from 435 mg/g for the reference material GP0 to 463, 447, 460 and 466 mg/g for the GP-L5, GP-L10, GP-LC5 and GP-LC10 materials respectively. FTIR spectra of GP-LC5 and GP-LC10 composites showed the aromatic vibration bands of the lignin skeleton. XRD and FTIR of the regenerated coals showed slight differences in crystallinity peaks and chemical functions compared to CA, respectively. Iodine index tests gave values higher than 600 mg/g. GP-LC10 and CAR900 materials with the respective adsorption capacities of 0.615 and 15.72 mg/g were the best adsorbents. The mechanisms of the MO adsorption reaction on these materials showed that the physisorption phenomenon was predominant. The GP-LC10 composite showed good agreement with the Thomas, Bohart-Adams and Nelson-Yoon models. The use of pozzolan-lignin geopolymer composites and regenerated activated carbons in adsorption process therefore constitutes viable options for removal of contaminants in waste waters.