New Sustainable Approach for the Production of Fe3O4/Graphene Oxide-Activated Persulfate System for Dye Removal in Real Wastewater

Abstract

Persulfate (PS)-activated, iron-based heterogeneous catalysts have attracted significant attention as a potential advanced and sustainable water purification system. Herein, a novel Fe 3 O 4 impregnated graphene oxide (Fe 3 O 4 @GO)-activated persulfate system (Fe 3 O 4 @GO+K 2 S 2 O 8 ) was synthesized by following a sustainable protocol and was tested on real wastewater containing dye pollutants. In the presence of the PS-activated system, the degradation efficiency of Rhodamine B (RhB) was significantly increased to a level of ≈95% compared with that of Fe 3 O 4 (≈25%). The influences of different operational parameters, including solution pH, persulfate dosage, and RhB concentration, were systemically evaluated. This system maintained its catalytic activity and durability with a negligible amount of iron leached during successive recirculation experiments. The degradation intermediates were further identified through reactive oxygen species (ROS) studies, where surface-bound SO 4 − was found to be dominant radical for RhB degradation. Moreover, the degradation mechanism of RhB in the Fe 3 O 4 @GO+K 2 S 2 O 8 system was discussed. Finally, the results indicate that the persulfate-activated Fe 3 O 4 @GO catalyst provided an effective pathway for the degradation of dye pollutants in real wastewater treatment.Water 2020, 12, 733 2 of 17 many advantages, such as a higher redox potential, wide pH range (2-11), longer life span, and more efficiency over •OH that enables excellent electron transfer of the oxidant toward higher contaminant degradation [6,7]. In general, the production of sulfate radicals can be obtained through PS activation by using several strategies, such as heat, ultraviolet, ultrasound, transition metal ions, carbonaceous-based materials, base, phenol, glucose, and ascorbic acid [8]. Consequently, transition-metal-based catalysts have been widely utilized as a PS activator due to their excellent catalytic efficiency [9]. However, the drawbacks of transition-metal-based catalysts for inhomogeneous systems include poor removal efficiency, precipitation of iron (III) as sludge, and less reusability, which has hindered their widespread use [10]. Hence, transition-metal-based heterogeneous catalyst systems have received tremendous attention for PS activation because of their environmentally friendly nature, high performance, simple operation stability, and high availability [11]. Iron (Fe)-based heterogeneous catalyst materials (e.g., Fe 3 O 4 ) have received much attention regarding frequently activating PS because of their high natural abundance, low price, and they could easily prevent secondary pollution through their recovery performance [12]. However, Fe 3 O 4 nanoparticles usually tend to aggregate in the solution, which can decrease their surface area and cause lower stability and catalytic efficiency [13]. Taking this into consideration, it is necessary to use a proper support that can enhance their overall performance. Graphene has been widely reported to be an emerging supporting material f...

Removal of Acid Yellow 17 from Textile Wastewater by Adsorption and Heterogeneous Persulfate Oxidation

“…Moreover, competition between carbonaceous substances will increase for free radical scavengers and free radicals due to the non-selective reactivity of free radicals. In many studies, the same effect in dye concentration was observed (Salari et al 2009 ; Saputra et al 2013 ; Frontistis et al 2015 ; Pervez et al 2020 ).…”

“…The reasons for this are; firstly, it is suitable for the production of reactive species with the increase in PS, which provides the appropriate amount of reactive for the oxidation of contaminants, and it enables easy reaction with the catalyst. Secondly, excessive use of PS decreases the formation of both economic and sulfate radicals (Pervez et al 2020 ). In other words, the sulfate radical may react with each other and turn into S 2 O 8 2− , this may lead to a decrease in efficiency.…”

“…COD removal increased as the dye concentration increased. As far as investigated in the literature, it was stated that increasing dye concentration negatively affects removal efficiency (Salari et al 2009 ; Saputra et al 2013 ; Pervez et al 2020 ). In this study, the color removal efficiency decreases as the dye concentration increases for color removal, while the removal efficiency increases with the increase of dye concentration for COD removal.…”

“…In this study, the decrease in efficiency with increasing contaminant concentration also shows that PAC active surfaces reach saturation since PAC is used as an activator. Dye adsorption reduced the catalytic performance by interfering with the electron transfer process (Pervez et al 2020 ). Moreover, competition between carbonaceous substances will increase for free radical scavengers and free radicals due to the non-selective reactivity of free radicals.…”

“…0.1 N NaOH and 0.1 N H 2 SO 4 (Carlo Erba, 99% purity) were used for pH adjustment, and NaCI (Sigma Aldrich, 99.5% purity) was used to study the salt effect. The reason for choosing NaCI for salt effect studies is that it is an electrolyte used in the textile industry to increase the adsorption of dye to fibers (Pervez et al 2020 ).…”