Papers by Keyword: Persulfate

Abstract: In recent years, the frequent use of antibiotics has led to the continuous release of antibiotics into the water environment, which not only poses a potential threat to public health, but also contributes to the generation and spread of antibiotic resistance. In addition, due to the high environmental persistence and low biodegradability of antibiotics, it is difficult to be effectively degraded by traditional water treatment processes. Therefore, it is urgent to develop clean and efficient treatment technologies. Advanced oxidation processes (AOPs), which can effectively remove refractory organic pollutants from water, has become a promising water treatment technology. In this regard, persulfate (PS)-based AOPs (PS-AOPs) has attracted extensive attention of researchers. In this system, PS can be activated by energy and catalysts to produce highly oxidizing active species, and achieve efficient degradation of antibiotics. Due to its rich surface functional groups, high specific surface area and high adsorption properties, researches on the activation of PS by carbonaceous materials have been reported continuously. In this paper, the research progress of carbon nanotubes, graphene, biological carbon, active carbon and hetero-atom doped carbon materials as catalysts to activate PS and degrade antibiotics is reviewed. In addition, the structure and properties of different carbon materials and the activation mechanism of free radical and non-free radical mediated by carbon materials were introduced, and the effects of PS dosage, catalyst dosage, temperature and pH on the degradation of antibiotics were discussed. Finally, this paper points out the important development direction in the future, that is, the development of environmental protection, high efficiency, low cost carbon materials and further research on the actual wastewater treatment performance.

Abstract: Very recently, crystallization of metallic glasses (MGs) has presented promising properties in the catalytic field. This work has investigated enhanced catalytic performance of crystallized Fe₇₈Si₉B₁₃ ribbons for fast activating persulfate (PS) with assistance of UV-vis light and heat. The ribbons were obtained by annealing at 750°C (Fe-A750) and cibacron brilliant yellow 3G-P (BY 3G-P) dye was used as pollutant. The results indicated that UV-vis light had limited capability to enhance PS activation efficiency by crystallized ribbons while the reaction rate using heat at 65°C was 7.5 times higher than at 25°C, suggesting an advanced performance with heat assistance of Fe-A750 ribbons. Activation energy ∆E for Fe-A750 was measured as 44.5 kJ mol^-1. In addition, 5 times reusability could be achieved for Fe-A750 ribbons under 45°C without catalytic decay. The surface morphologies of glassy ribbons, as-annealed Fe-A750 ribbons, HCl-treated Fe-A750 ribbons and after-reused Fe-A750 ribbons have also been systematically studied. This work provides a novel clue to promote applicability of novel crystallized ribbons from MGs.

Abstract: In this work, the heat-activated persulfate (PS) in the presence of Fe₇₈Si₉B₁₃ metallic glasses (MGs) shows an extremely difference in degradation of azo dye and triarylmethane dye, where Fe₇₈Si₉B₁₃ MGs exhibits a superior activation ability for PS with assistance of heat leading to the fast removal of two dyes. The structural features of Fe₇₈Si₉B₁₃ MGs are firstly characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), following analysis of surface topography by scanning electron microscope (SEM). The results show that with the addition of Fe₇₈Si₉B₁₃ MGs, the recalcitrant azo dye is completely removed within 5 min while only 6% of removal rate can be achieved without adding MGs, indicating that the refractory azo dye can be easily degraded by sulfate radical (SO₄•^–) from heat/MGs/PS. On the other hand, no big variation occurs between PS and MGs/PS under heat activation in degrading triarylmethane dye. Sole PS activated by heat results in a fast removal rate, indicating that triarylmethane dye can be easily degraded by PS itself compared to azo dye. The findings in this work present an in-depth understanding of heat/MGs/PS system in dyes degradation.

Abstract: At the ambient temperatures, the influence of operating conditions on persulfate (S₂O₈) oxidation of real textile wastewater was investigated for the removal of color, suspended solids (SS) and chemical oxygen demand (COD). The effects of oxidant dosage, initial solution pH and contact time were studied in a series of batch experiments using persulfate (PS) oxidant as sodium persulfate. Oxidant dose was defined by an oxidant/contaminant (PS/COD) molar ratio, varied from 1/1-10/1. Although parameter removals increased with the oxidant dose, especially for color and SS, a PS/COD molar ratio of 4/1 (6720mg/L) was adopted in a bid to use fewer chemicals. The pH was varied from 2-11, with pH of between 2 and 3 being the optimum. At 360minutes contact time, the removals of color, SS and COD were 84%; 71% and 32% respectively. Although relatively effective, especially for color removal, results show that the reactions might have been inhibited at ambient temperatures as shown by the particularly low removal of COD.

Abstract: The oxidation of 16 polycyclic aromatic hydrocarbons compounds (PAHs) in sediments by sodium persulfate (Na₂S₂O₈) activated by temperature and nanoscale zero−valent iron (nZVI) as the source of catalytic ferrous iron was investigated. The effect of various controlling factors including S₂O₈²⁻ (0.017–170 g/L), nZVI (0.01–1 g/L), and temperature (50–70°C) were performed. The efficiency to remove PAHs was not too high as 10.7–39.1% for unactivated persulfate. Results from experiments indicate that increasing temperature or the addition of nZVI into a persulfate-slurry system could enhance the persulfate oxidation process. The best removal efficiency (86.3%) was attained after 24 hr while adding nZVI (0.5 g/L) to persulfate (170 g/L) at temperature of 25°C. The results of our study suggest that nZVI assisted persulfate oxidation without elevating temperature is a suitable and economic alternative for the ex–situ treatment of PAHs contaminated sediments.

Abstract: Taking anthraquinone dye reactive brilliant blue KN-R as a target pollutant, this paper studied KN-R degradation rates and electric generation performances in the system of Fe²⁺/PDS and Fe²⁺/PDS-MFC. The Fe²⁺/PDS system is that persulfate (PDS) is activated by ferrous iron (Fe²⁺) ,while Fe²⁺/PDS-MFC system is using Fe²⁺/PDS system as the cathode of microbial fuel cells (MFC) .The results showed that in the two systems, the KN-R degradation rate was increased and then decreased with the increase of initial Fe²⁺ dosage. With the increase of pH, the KN-R degradation rapid declines. In the two systems, both of the KN-R degradation reaction was divided into two stages. In addition, the process of reaction conforms to the first-order kinetic equation. Compared with Fe²⁺/PDS system, the Fe²⁺/PDS-MFC system’s ability to degrade pollutants have little change, the main advantage of Fe²⁺/PDS-MFC system is able to obtain higher and more stable power. Under an optimal condition, the maximum power density achieved 294.07 mW/m², the KN-R degradation rate was 96.90%.

Abstract: The decolourization of dye wastewater by persulfate was studied using kiscolon scarlet2KN as a model dye wastewater. Effects of several parameters, such as dose of oxidant, pH, temperature and UV irradiation, were investigated in detail. The results showed that the decolourization reaction of kiscolon scarlet2KN by persulfate could be fitted to a pseudo-first order kinetics model. In addition, when the oxidant amount used is 70 times of kiscolon scarlet2KN, pH 5.71 and reaction temperature for 70°C, kiscolon scarlet2KN decolorization rate can reach more than 98%. The results are useful for the treatment of dye wastewater. Keywords: Kiscolon scarlet 2KN, Decolourization, Persulfate

Abstract: The phenol oxidation with persulfate catalyzed were studied. Effects of several parameters, such as dose of oxidant, pH, temperature and UV irradiation, were investigated in detail. The results showed that the phenol oxidation by persulfate could be fitted to a pseudo-first order kinetics model. The optimum acidity of the phenol oxidation system in the paper is ca. pH 8.76, the optimum temperature which is ca.70 °C and the optimum molar ratio of persulfate to the phenol is ca.40 in the solution.The results are useful for the treatment of industrial wastewater. Key words: Phenol oxidation Schiff base manganese (III) complexes Persulfate

Abstract: Semi Volatile Organic Compounds (SVOCs) are common contaminants found in brownfield sites that used to be agrochemical plants, chemical storage sites, and industrial areas. Chemical oxidation showed great potential to provide a rapid, cost-effective approach for SVOCs contaminate sites. Chemical oxidation using persulfate was demonstrated by degrading both lab samples and on-site samples from a local o-ansidine contaminated site in this study. The soil samples were mixed with persulfate at different ratios, while adding supplements for the purpose of persulfate thermal activation and pH control. Experiments for optimal usage and treatment duration were also investigated to provide guidance for following demonstration project. Soil samples were analyzed before and after the treatments to compare the o-ansidine concentration changes. The results suggested an optimal ratio of persulfate at 0.5% (in w/w) for this study, with 90% or more removal of most samples in 3 days, at an average cost of oxidants per ton of soil around 800 RMB. This study demonstrated the potential of persulfate oxidation as a novel and reliable approach for o-ansidine contaminated soil, as well as the possibility of extending the remediation concept for other organic contamination scenarios. In addition, persulfate oxidation could also be combined with other remediation technology in future due to its simplicity and convenience.

Abstract: The decolourization of dye wastewater by persulfate was studied using methylene blue as a model dye wastewater. Effects of several parameters, such as dose of oxidant, ionic strength, pH, temperature and UV irradiation, were investigated in detail. The results showed that the decolourization reaction of methylene blue by persulfate could be fitted to a pseudo-first order kinetics model. In addition, when the oxidant amount used is 2 times of methylene blue, pH 3.43 and reaction temperature for 60°C, after uv light under the irradiation of 20 min, methylene blue decolorization rate can reach more than 98%. The results are useful for the treatment of dye wastewater.