title: Synthesis of lignin-base cationic flocculant and its application in removing anionic azo-dyes from simulated wastewater.
abstract: In this paper the Mannich reaction product of dimethylamine, acetone and formaldehyde was grafted onto hydroxymethylated lignin to form a lignin-base cationic polyelectrolyte (L-DAF). L-DAF samples with different cationic strengths and molecular weights were synthesized and characterized. Their performance as a cationic flocculant in removing three anionic azo-dyes (Acid Black, Reactive Red and Direct Red) from simulated dye wastewater was evaluated. The removal of anionic dyes by L-DAF was ascribed to two simultaneous mechanisms, which included coagulation by charge neutralization and flocculation by bridging. There was a different optimum dose of flocculant for each dye wastewater, at which dye removal can reach above 95%. Furthermore, a longer settling time and a lower solution pH increased the efficiency of the decolorization process. During the treatment, more than 89% of chemical oxygen demand (COD) reduction was achieved with sludge production being less than 5.4%.
authors.affiliation: College of Material Science and Engineering, Fuzhou University, Fuzhou City, Fujian Province, China.
authors.forename: Run
authors.initials: R
authors.lastname: Fang
authors.forename: Xiansu
authors.initials: X
authors.lastname: Cheng
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Xu
mesh_terms: D000096:Acetone / Q000737:chemistry; D000838:Anions; D001391:Azo Compounds / Q000302:isolation & purification*; D001673:Biodegradation, Environmental / Q000187:drug effects; D002412:Cations; D004396:Coloring Agents / Q000302:isolation & purification*; D004123:Dimethylamines / Q000737:chemistry; D005427:Flocculation / Q000187:drug effects; D005557:Formaldehyde / Q000737:chemistry; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008031:Lignin / Q000378:metabolism*; D008956:Models, Chemical; D010100:Oxygen / Q000302:isolation & purification; D012492:Salts / Q000494:pharmacology; D012722:Sewage / Q000032:analysis; D012996:Solutions; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D000838:Anions; D001391:Azo Compounds; D002412:Cations; D004396:Coloring Agents; D004123:Dimethylamines; D012492:Salts; D012722:Sewage; D012996:Solutions; D000096:Acetone; D005557:Formaldehyde; D008031:Lignin; C034516:dimethylamine; D010100:Oxygen