Chemically Derivatized Textile Cotton Dust for in situ Remediation of Colored Waste Waters

摘要

A large size textile company such as Döhler S/A when fully processing cotton yarngenerates a daily amount about 1.5 ton of cotton dust waste (CDW) spread by the factory ground andweaver looms. This is essentially pure cellulose except by less than 5% contamination of mineralpowder and grease from the collection operation. CDW conversion into anionic and cationic insolublederivatives was carried out using monochloroacetic acid (MCAA) and diethylaminoethylchloride.hydrochloride (DEAE) under strong alkaline conditions. A factorial approach was carried outlooking for the influence of three variables on carboxymethylation: a) alkali concentration; b) amountof MCAA; c) addition of isopropanol. For the DEAE-cellulose synthesis were analyzed two variables:a) alkali concentration and b) amount of DEAE. Another feedstuff as starting material, cane bagasse,led to a significant loss of both hemicellulose (15 to 30%) and lignin, thus generating a subadjacentenvironmental problem given that both polymers turn almost completely soluble under the strongalkali action. Comparatively, CDW experienced a mass loss of < 5%, a reflex of its completeinsolubility in water and even alkali. Advantageously, ionic CDWs display: 1. Complete insolubility inwater or even in strong alkalis or diluted acids. 2. Full local supply. 3. High availability of threereactive hydroxyl groups for derivatization (C6, C2, C3 per anhydroglucose residue); 4. Ionic matrixwith facilitated flow for liquid waste streams. 5. Minimal loss of alkali-solubilized components. Forboth derivatives (CM~-- and DEAE~+-CDW), the variable alkali concentration was the more significantfactor. As an example CM--CDW retained 64.50 mg.g~(-1) of Basic Blue 41 and DEAE~+-CDW- retained93 mg.g~(-1) of Reactive Red 239 in batch experiments. So, our results are indicating that a parcel of thecollected CDW may be diverted from its actual exclusive use, namely, burning for vapor and energygeneration, towards ionic derivatives for the efficient sequestering of basic and acid residual dyes fromthe stream of waste water. Given their binding capabilities, both kind of CDW ionic matrix may alsoremediate toxic cations (Cr+6 from the mordant potassium dichromate; Hg~(2+), Cd~(2+)) and anions (SO_4~(2-),Cl-, HCO~(3-), NO_3~-) in the utilized water. CDW, in a textile factory, is an in situ waste which, followingone pot derivatization, may provide remediation to an environmental problem, the processing andacceptable disposal of colored waste waters.