Iron-loaded leonardite powder for Fenton oxidation of Reactive Red 180 dye removal.

Fenton oxidation is an effective and valuable method for wastewater treatment. To inhibit environmental impacts and increase overall reaction efficiencies, it is important to develop advanced catalysts. This paper illustrates an experimental study on the elimination of RR180 dye from synthetic aqueous solutions with raw leonardite and different iron-loaded leonardite powders, Fe(0)-loaded leonardite, and Fe(II)-loaded leonardite. The effect of solution pH (2.0-6.0), catalyst amount (0.10-1.5 g/L), H2O2 concentration (10-50 µL/L), and dye concentration (10-30 ppm) was tested to achieve maximum color removal efficiency using the three catalysts. At pH = 2, color removal efficiencies were higher and more suitable. Initial experiments showed the advantage of using Fe(II)-loaded leonardite on using Fe(0)-loaded leonardite. Fe(II)-loaded leonardite catalyst was the most efficient in RR180 color removal compared to the other tested reagents. Color removal in function of solution pH did not decrease much when Fe(II)-loaded leonardite was used (100 to 96%) when pH was increased from 2.0 to 6.0. In the other hand, dye removal has been significantly affected in the case of using raw leonardite, Fe(0)-loaded leonardite (93 to 0%), and (100 to 13%) in the same pH range, respectively. At optimum experimental conditions, catalyst amount: 0.75 g/L for Fe(II) and Fe(0)-loaded leonardite and 1.5 g/L for raw leonardite; dye concentration: 10 ppm; solution pH: 2.0; H2O2 concentration: 50 µL/L; volume: 100 mL and reaction time: 60 min, RR180 dye removal efficiencies were 91%, 100%, and 100% by raw leonardite, Fe(0)-loaded leonardite and Fe(II)-loaded leonardite, respectively. The stability and reusability of the tested catalyst was investigated up to ten cycles. The experimental results revealed that both Fe(0)-loaded leonardite and Fe(II)-loaded leonardite can be used in Fenton reaction up to four cycles without decreasing their efficiency in RR180 color removal. The characterization of the catalysts was established using scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX). The synthesized catalyst can be used at large scale in any textile industry to effectively remove dyes resulting in high elimination rates at the optimal determined and studied conditions.

Production of Bio-Based Pigments from Food Processing Industry By-Products (Apple, Pomegranate, Black Carrot, Red Beet Pulps) Using Aspergillus carbonarius.

Food processing industry by-products (apple, pomegranate, black carrot, and red beet pulps) were evaluated as raw materials in pigment production by the filamentous fungi Aspergillus carbonarius. The effect of fermentation conditions (solid and submerged-state), incubation period (3, 6, 9, 12, and 15 d), initial substrate pH (4.5, 5.5, 6.5, 7.5, and 8.5), and pulp particle size (<1.4, 1.4-2.0, 2-4, and >4 mm) on fungal pigment production were tested to optimize the conditions. Pigment extraction analysis carried out under solid-state fermentation conditions showed that the maximum pigment production was determined as 9.21 ± 0.59 absorbance unit at the corresponding wavelength per gram (AU/g) dry fermented mass (dfm) for pomegranate pulp (PP) by A. carbonarius for 5 d. Moreover, the highest pigment production was obtained as 61.84 ± 2.16 AU/g dfm as yellowish brown at initial pH 6.5 with < 1.4 mm of substrate particle size for 15-d incubation period. GC×GC-TOFMS results indicate that melanin could be one of the main products as a pigment. SEM images showed that melanin could localize on the conidia of A. carbonarius.

Electrocoagulation and electrooxidation pre-treatment effect on fungal treatment of pistachio processing wastewater.

The effect of electrochemical pre-treatment on fungal treatment of pistachio processing wastewater (PPW) was investigated. Electrocoagulation (EC) and electrooxidation (EO) were used as electrochemical pre-treatment step before fungal treatment of PPW. Aluminum (Al/Al), iron (Fe/Fe), and stainless steel (SS/SS) electrode pairs were selected as anode/cathode for EC whereas boron doped diamond (BDD/SS) was preferred as anode/cathode electrode pairs for EO experiments in this study. The impact of current density (50-300 A/m2) and operating time (0-240 min) were tested for chemical oxygen demand (COD) and total phenol removal. After pre-treatment of PPW, four different fungus species (Coriolus versicolor, Funalia trogii, Aspergillus carbonarius, and Penicillium glabrum) were tested for further treatment. Penicillium glabrum supplied maximum COD and total phenol removal efficiency compared to other fungus strains. The combined electrochemical-assisted fungal treatment process supplied 90.1% COD and 88.7% total phenol removal efficiency when supported with EO pre-treatment. Pre-treatment of PPW with EO method provided better results than EC method for fungal treatment. Operating cost of the combined process was calculated as 6.12 US$/m3. The results indicated that the proposed combined process supplied higher pollutant removal compared to the individual electrocoagulation, electrooxidation, and fungal treatment process.