Common industrial dyes of varying colors and types.
Industrial dye degradation is any of a number of processed by which
dyes are broken down, ideally into innocuous products.[1] Many dyes, specifically in the textile industry such as methylene blue or methyl red, are released into ecosystems through water waste.[2] Many of these dyes can be carcinogenic. In
paper recycling dyes can be removed from fibres during a
deinking stage prior to degradation.
Methods
Standard photocatalysis set-up
Heterogeneous photocataylsis is one approach to the degradation of dyes.[3]
As applied to dye-containing effluents from the
textile industry, several approaches are standardized for removal or degradation of dyes.[4] These include oxidation, e.g. using air or
hydrogen peroxide,
ozone, or
Fenton chemistry. One challenge is that oxidants can be indiscriminent such that large amounts of reagents can be required (see
Chemical oxygen demand). One promising approach combines oxidation with
photocatalysis.[5] Reduction is also employed, a standard reagent being
dithionite, which traditionally affords leuco dyes. Precipitation, often coupled with
flocculation, is yet another approach, although it can produce substantial quantities of solids.
References
^Rauf, M.A.; Ashraf, S. Salman (2009). "Fundamental principles and application of heterogeneous photocatalytic degradation of dyes in solution". Chemical Engineering Journal. 151 (1–3): 10–18.
doi:
10.1016/j.cej.2009.02.026.
^ Huang, C.; Y. Huang; H. Cheng; Y. Huang. Kinetic Study of an Immobilized Iron Oxide for Catalytic Degradation of Azo Dye Reactive Black B with Catalytic Decomposition of Hydrogen Peroxide. Catalysis Communications 2009, 10 (5), 561-566.
^Sewekow, Ulrich (2016). "Textile Dyeing, 7. Legal Aspects, Toxicology, and Ecology". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–11.
doi:
10.1002/14356007.u26_u06.
ISBN9783527306732.
^Shafiq, Iqrash; Hussain, Murid; Shehzad, Nasir; Maafa, Ibrahim M.; Akhter, Parveen; Amjad, Um-e-salma; Shafique, Sumeer; Razzaq, Abdul; Yang, Wenshu; Tahir, Muhammad; Russo, Nunzio (August 2019). "The effect of crystal facets and induced porosity on the performance of monoclinic BiVO4 for the enhanced visible-light driven photocatalytic abatement of methylene blue". Journal of Environmental Chemical Engineering. 7 (4): 103265.
doi:
10.1016/j.jece.2019.103265.
ISSN2213-3437.
S2CID198742844.