Coagulation-flocculation of azo dye Acid Orange 7 with green refined laterite soil

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• 作者：Yen-Yie Lau^a ; Yee-Shian Wong^a ; ^b ; Tjoon-Tow Teng^a ; ^{ttteng@usm.my" class="auth_mail} ; Norhashimah Morad^a ; Mohd Rafatullah^a ; Soon-An Ong^b
• 关键词：Laterite soil ; Coagulation ; Azo dye ; Acid Orange 7 ; Dye degradation
• 刊名：Chemical Engineering Journal
• 出版年：15 June, 2014
• 年：2014
• 卷：246
• 期：Complete
• 页码：383-390
• 全文大小：1584 K

文摘

A novel degradation pathway of Acid Orange 7 (AO 7) by laterite soil in coagulation process is suggested. AO 7 has a strong azo bond links with benzene and naphthalene rings. The rings in AO 7 can be cleaved during coagulation and flocculation by laterite soil. Laterite soil rich in silica component could treat AO 7 with 98.43% color removal at pH 2. It could degrade azo dye molecule to the simplest hydrocarbon structure and non-toxic products in coagulation process through a linkage of reactions: CN bond cleavage, desulfonation, silication, diazene reductase and polymerization. Ascertainment of the degradation pathway and products were characterized by UV-Vis and FT-IR techniques. The results show that laterite soil is bi-functional as a coagulant as well as a flocculant. Sludge Volume Index (SVI) with sludge generated as low as 21.703 mL/g provides evidence that, laterite soil has polymerization characteristic by forming n-methylsisiloxane and n-methyldisilathiane. Laterite soil detached sulfate ion in AO 7 to form n-methyldisilathiane, indirectly preventing sulfate ion to be exposed to environment.