Submitted to: Environmental Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 11, 1999
Publication Date: N/A
Interpretive Summary: The textile industry is the most polluting of all industries worldwide, considering both the volume and composition of the effluent discharged. Treatments to remove dyes from textile wastewaters add significantly to the cost of production of finished goods; costs which are passed along to the consumer. A new polymer, derived from a byproduct (kraft lignin) of the pulp and paper industry, has been developed that can be used to decolorize textile effluents. This new polymer is simple to make, employing just one chemical treatment step and one enzymatic treatment step to prepare the material. The simplicity and high efficiency of this procedure compared to previously developed methods indicates that the polymer can provide a cost-effective means to treat textile wastewaters.
Technical Abstract: The ability of cationic kraft lignin to function as a flocculant for decolorization of textile wastewaters was examined. Kraft lignin was quaternized with high efficiency in alkaline solution with 3-chloro-2-hydroxypropyl-trimethylamonium chloride. The product formed was separated into 2 fractions arbitrarily based on their aqueous solubility at pH7. The pH7-soluble fraction was soluble over the pH2 to 13 range. The pH7-insoluble fraction was soluble at low (less than pH4) and high pH (greater than pH12). Treatment of the pH7-soluble quaternized lignin fraction with soybean peroxidase and hydrogen peroxide under nitrogen produced a soluble, high molecular weight polymer, as determined by ultrafiltration analysis. Peroxidase treatment of the pH7-insoluble fraction at pH3 produced a material not completely soluble at any pH, probably by modifying the lignin structure but not necessarily by increasing its molecular weight. All quaternized lignin fractions were demonstrated to bind Orange II and hydrolyzed Reactive Red 180, but only peroxidase-polymerized lignin produced rapidly settling flocs. Peroxidase-treated, quaternized kraft lignin can be used in place of synthetic cationic polymers for decolorization of textile wastewaters.