Abstract
Releasing of dye-containing wastewater by the textile industry into general water bodies can adversely affect aquatic ecosystems and human health. The objective of this study is to assess the Congo red dye biodegradation and detoxification by immobilized Aspergillus niger obtained from textile dye wastewater. The effects of process parameters like pH, temperature, reaction time and initial concentration on Congo red degradation were studied. Equilibrium adsorption isotherms, kinetics and thermodynamics were also investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data fitted well to Langmuir isotherm and the kinetic data fitted well to the pseudo-second-order model. The degraded metabolites of Congo red were characterized by using UV–Vis spectrophotometer, Fourier transform infrared spectroscopy and high-performance liquid chromatography, further confirmed that biodegradation of Congo red was due to reduction of the azo bond. Phytotoxicity test confirmed that degradation metabolites were a less toxic than original dye. The reusability of the immobilized Aspergillus niger was repeated with six cycles and removal efficiency ranged from 98 to 72%. The results in this study substantiate that immobilized Aspergillus niger could be employed as a good adsorbent for the removal of Congo red dye from wastewater.
Highlights
Developed countries are facing many challenges, such as the limited freshwater resources, increasing food demand, rising population, industrial activities ‘pollution and stress linked to change in climate conditions
The technology of immobilized fungal cells is being increasingly used in industrial application wastewater treatment due to several advantages which are more resilient to environmental perturbations such as pH, or exposure to toxic chemical concentrations, mechanical strength, chemical stability, cost effective, physical morphology, long retention time, anti-degradation ability and cell viability for several cycles of operations (Wesenberg et al 2003)
One isolate was selected for further studies based on its ability to degrade Congo red from liquid medium efficiently and rapidly showing more than 98.8% decolourization Fig. 1
Summary
Developed countries are facing many challenges, such as the limited freshwater resources, increasing food demand, rising population, industrial activities ‘pollution and stress linked to change in climate conditions. Textile of many industries such as paper, cosmetics, rubber, plastic, leather, food, photo graphical and pharmaceutical purposes are containing a variety of dyes and auxiliary chemicals that consume a huge amount of water each day and produce large quantities of wastewater that contain many hazardous compounds. Applied Water Science (2021) 11:35 red is one of the common azo dyes, which has two Azo bonds (–N=N–) connected to aromatic rings, that is used in the textile industry (Konstantinou et al 2004) It consists of a sodium salt of benzidinediazo-bis-1- naphtylamine-4 sulfonic acid (Bentahar et al 2016). As an adsorbent material, is the most widely used one due to its naturally availability, good action exchange capacity, high surface area, micro-porous structure, and less cost (Alam et al 2018) For all these advantages, this work focuses on two main objectives to investigate the potential of immobilized fungi for decolorization and degradation of textile Congo red dye
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