Comparative study of toxicity of azo dye Procion Red MX-5B following biosorption and biodegradation treatments with the fungi Aspergillus niger and Aspergillus terreus

Abstract

Azo dyes are an important class of environmental contaminants and are characterized by the presence of one or more azo bonds (-N=N-) in their molecular structure. Effluents containing these compounds resist many types of treatments due to their molecular complexity. Therefore, alternative treatments, such as biosorption and biodegradation, have been widely studied to solve the problems caused by these substances, such as their harmful effects on the environment and organisms. The aim of the present study was to evaluate biosorption and biodegradation of the azo dye Procion Red MX-5B in solutions with the filamentous fungi Aspergillus niger and Aspergillus terreus. Decolorization tests were performed, followed by acute toxicity tests using Lactuca sativa seeds and Artemia salina larvae. Thirty percent dye removal of the solutions was achieved after 3 h of biosorption. UV-Vis spectroscopy revealed that removal of the dye molecules occurred without major molecular changes. The acute toxicity tests confirmed lack of molecular degradation following biosorption with A. niger, as toxicity to L. sativa seed reduced from 5% to 0%. For A. salina larvae, the solutions were nontoxic before and after treatment. In the biodegradation study with the fungus A. terreus, UV-Vis and FTIR spectroscopy revealed molecular degradation and the formation of secondary metabolites, such as primary and secondary amines. The biodegradation of the dye molecules was evaluated after 24, 240 and 336 h of treatment. The fungal biomass demonstrated considerable affinity for Procion Red MX-5B, achieving approximately 100% decolorization of the solutions by the end of treatment. However, the solutions resulting from this treatment exhibited a significant increase in toxicity, inhibiting the growth of L. sativa seeds by 43% and leading to a 100% mortality rate among the A. salina larvae. Based on the present findings, biodegradation was effective in the decolorization of the samples, but generated toxic metabolites, while biosorption was effective in both decolorization and reducing the toxicity of the solutions.

Elimination of Industrial Textile Dye by Electrocoagulation Using Iron Electrodes

“…activated carbons, silica, biosorbents), membrane separation 3,4 (e.g., microfiltration ultrafiltration, nanofiltration), precipitation 5 , photo degradation [6][7] , biodegradation 8,9 , coagulation and electrocoagulation [10][11][12][13][14][15] .…”

Biosorption optimization and equilibrium isotherm of industrial dye compounds in novel strains of microscopic fungi

“…In recent years, there has been an increasing interest in the ligninolytic capabilities of microfungi, which, similarly to the white-rot fungi, can remove a broad spectrum of aromatic compounds from wastewater. There are various fungi, other than white-rot fungi, such as Aspergillus niger, Aspergillus terreus, Rhizopus arrhizus, Rhizopus oryzae, Penicillium sp., Trichoderma harzianum and Haematonectria haematococca, which can also remove diverse dyes through biosorption (Almeida and Corso 2014;Fu and Viraraghavan 2000, 2002bGallagher et al 1997;O'Mahony et al 2002;Yang et al 2011;Zhou and Banks 1991).…”

Characterization and photocatalytic performance of SnO2–CNT nanocomposites

“…The discharge of organic dyes into water systems can constitute environmental pollution because the dyes are often highly toxic and subject to bioaccumulation [1][2][3]. Some dyes can decompose into aromatic amines under aerobic conditions to produce carcinogenic or mutagenic effects in humans [4]. Dye-containing effluents are highly colored and can affect the photosynthetic activity of aquatic life by reducing the sunlight penetration into water.…”