One-step preparation of a novel graphitic biochar/Cu0/Fe3O4 composite using CO2-ambiance pyrolysis to activate peroxydisulfate for dye degradation

Herein,a one-step co-pyrolysis protocol was adopted for the first time to prepare a novel pyrogenic carbon-Cu⁰/Fe₃O₄ heteroatoms (FCBC) in CO₂ ambiance to discern the roles of each component in PDS activation.During co-pyrolysis,CO₂ catalyzed formation of reducing gases by biomass which facilitated reductive transformation of Fe³⁺ and Cu²⁺ to Cu⁰ and Fe₃O₄,respectively.According to the a...     

Rapid and simple spectrophotometric determination of persulfate in water by microwave assisted decolorization of Methylene Blue

A rapid and simple method for determination of persulfate in aqueous solution was developed. The method is based on the rapid reaction of persulfate with Methylene Blue(MB) via domestic microwave activation, which can promote the activation of persulfate and decolorize MB quickly. The depletion of MB at 644 nm(the maximum absorption wavelength of MB) is in proportion to the increasing concentration of persulfate in aqueous solution. Linear calibration curve was obtained in the range 0–1.5 mmol/L, with a limit of detection of 0.0028 mmol/L. The reaction time is rapid(within 60 sec), which is much shorter than that used for conventional methods. Compared with existing analytical methods, it need not any additives, especially colorful Fe2+, and need not any pretreatment for samples, such as p H adjustment.     

Removal of polycyclic aromatic hydrocarbons from different soil fractions by persulfate oxidation

Removal of polycyclic aromatic hydrocarbons (PAHs) from different soil fractions of contaminated soil was investigated by using activated persulfate oxidation remediation in our research. The results showed that the light fraction, which accounted for only 10% of the soil, contained 30% of the PAHs at a concentration of 4352?mg/kg. The heavy fraction contained more high-molecular-weight PAHs, and the total PAH concentration was 625?mg/kg. After being oxidized, the removal rate of PAHs was 39% in the light fraction and nearly 90% in the heavy fraction. Among the different fractions of the heavy fraction, humic acid contained the highest concentration of PAHs, and consequently, the highest removal efficiency of PAHs was also in humic acid. Compared with the light fraction, the heavy fraction has more aromatic compounds and those compounds were broken down during the oxidation process, which may be the removal mechanism involved in the oxidation of high-ring PAHs. Similarly, the enhancement of C = C bonds after oxidation can also explain the poor removal of high-ring PAHs in the light fraction. These results imply that different fractions of soil vary in composition and structure, leading to differences in the distribution and oxidation efficiencies of PAHs.     

Integration of microbial reductive dehalogenation with persulfate activation and oxidation (Bio-RD-PAO) for complete attenuation of organohalides

•Bio-RD-PAO can effectively and extensively remove organohalides. •Bio-RD alone effectively dehalogenate the highly-halogenated organohalides. •PAO alone is efficient in degrading the lowly-halogenated organohalides. •The impacts of PAO on organohalide-respiring microbial communities remain elusive. •Bio-RD-PAO provides a promising solution for remediation of organohalide pollution. Due to the toxicity of bioaccumulative organohalides to human beings and ecosystems, a variety of biotic and abiotic remediation methods have been developed to remove organohalides from contaminated environments. Bioremediation employing organohalide-respiring bacteria (OHRB)-mediated microbial reductive dehalogenation (Bio-RD) represents a cost-effective and environmentally friendly approach to attenuate highly-halogenated organohalides, specifically organohalides in soil, sediment and other anoxic environments. Nonetheless, many factors severely restrict the implications of OHRB-based bioremediation, including incomplete dehalogenation, low abundance of OHRB and consequent low dechlorination activity. Recently, the development of in situ chemical oxidation (ISCO) based on sulfate radicals (SO₄^·−) via the persulfate activation and oxidation (PAO) process has attracted tremendous research interest for the remediation of lowly-halogenated organohalides due to its following advantages, e.g., complete attenuation, high reactivity and no selectivity to organohalides. Therefore, integration of OHRB-mediated Bio-RD and subsequent PAO (Bio-RD-PAO) may provide a promising solution to the remediation of organohalides. In this review, we first provide an overview of current progress in Bio-RD and PAO and compare their limitations and advantages. We then critically discuss the integration of Bio-RD and PAO (Bio-RD-PAO) for complete attenuation of organohalides and its prospects for future remediation applications. Overall, Bio-RD-PAO opens up opportunities for complete attenuation and consequent effective in situ remediation of persistent organohalide pollution.     

Overestimate of remediation efficiency due to residual sodium persulfate in PAHs contaminated soil and a solution

Oxidation remediation is a commonly used technology for PAHs contaminated soil presently,but the overestimate of efficiency due to ongoing remediation by residual oxidants during extraction and testing has not been paid enough attention.In this study,persulfate was activated by Fe（Ⅱ） to inve stigate the effects of residual oxidants on PAHs removal during detection process and the elimination effects of adding Na₂ SO₃ and extending sampling time on residual oxidants.Results ...     

海水中总氮的测定方法比较研究

通过标准曲线、检出限和测定范围、方法精密度、方法准确度、实际海水样品测定结果、加标回收率、分析效率和物料消耗这几方面比较了过硫酸钾氧化法、流动注射分析法和高温氧化-化学发光检测法这3种测定海水中总氮(TN)方法的优缺点。结果表明,流动注射分析法和高温氧化-化学发光检测法的测定范围更宽,精密度、准确度更好,3种样品的加标回收率达到96.2%~101%;高温氧化-化学发光检测法分析效率高、物料消耗少、节能环保,适用于一般海水样品的批量分析,且由于测定范围大,该法也适用于TN浓度较高的海水样品的批量分析,流动注射分析法因其较低的检出限更适用于TN浓度较低的海水样品的批量分析。     

Degradation of acetic acid with sulfate radical generated by persulfate ions photolysis

The photolysis of was studied for the removal of acetic acid in aqueous solution and compared with the H₂O₂/UV system. The radicals generated from the UV irradiation of ions yield a greater mineralization of acetic acid than the OH radicals. Acetic acid is oxidized by radicals without significant formation of intermediate by-products. Increasing system pH results in the formation of OH radicals from radicals. Maximum acetic acid degradation occurred at pH 5. The results suggest that above this pH, competitive reactions with the carbon mineralized inhibit the reaction of the solute with and also OH radicals. Scavenging effects of two naturally occurring ions were tested; in contrast to ions, the presence of Cl⁻ ions enhances the efficiency of the /UV process towards the acetate removal. It is attributed to the formation of the Cl radical and its great reactivity towards acetate.     

A novel pretreatment process of mature landfill leachate with ultrasonic activated persulfate: Optimization using integrated Taguchi method and response surface methodology

A novel advanced oxidation process (AOP) using ultrasonic activated persulfate oxidation was used to pretreat mature landfill leachate. The effects of different operating variables (e.g., the initial S₂O₈²⁻ concentration, pH, temperature, ultrasonic power and reaction time) on the oxidation performance were investigated regarding the total organic carbon (TOC) removal efficiency, and the variables were optimized using the integrated Taguchi method and response surface methodology (RSM). Based on the Taguchi method under L₁₆ (4⁵) arrays and a grey relational analysis, the most significant variables included the initial S₂O₈²⁻ concentration, temperature and reaction time. The concentrations of these variables were further optimized using RSM. Using the integrated optimization method, the optimal conditions included an initial S₂O₈²⁻ concentration of 8.5 mM, a reaction temperature of 70 °C and a reaction time of 2.46 h, which resulted in a TOC removal efficiency of 77.32%. The experimental results showed that the enhanced TOC removal from mature landfill leachate by sono-activated persulfate oxidation could be attributed to the combined effects of ultrasonic catalysis and sulfate radical-AOP. Overall, ultrasonic activated persulfate oxidation is a promising method for the pretreatment of landfill leachate.     

A novel graphene oxide-carbon nanotubes anchored α-FeOOH hybrid activated persulfate system for enhanced degradation of Orange II

Persulfate activation has been applied as one of the efficient advanced oxidation processes(AOPs) to remediate polluted environments. In this study, a novel α-FeOOH anchored by graphene oxide(GO)-carbon nanotubes(CNTs) aerogel(α-FeOOH@GCA) nanocomposite activated persulfate system(α-FeOOH@GCA + K_2S_2O_8) was applied for decolorization of Orange Ⅱ(OⅡ). The decolorization of OⅡ was remarkably enhanced to a level of ～ 99% in this system compared with that of pristine α-FeOOH(～ 44%) or GO-CNTs(～18%). The enhanced catalytic activity of α-FeOOH@GCA was due to the formation of a heterojunction byα-FeOOH and GO-CNTs as confirmed by the presence of Fe–O–C chemical bonds. The degradation intermediates of OⅡ were comprehensively identified. The proposed degradation pathway of OⅡ begins with the destruction of the conjugated structures of OⅡ by the dominant reactive oxygen species, surface-bound SO_4~(·-). The decolorization efficiency of OⅡ by the α-FeOOH@GCA activated persulfate system decreased from the first to third cycle of recycling. Ultraviolet(UV) irradiation or introduction of a small amount of Fe~(2+) could restore the activation of this system. The results show that the α-FeOOH@GCA persulfate activation system promises to be a highly efficient environmental remediation method for organic pollutants.     

A novel co-catalyzed system between persulfate and chlorite by sonolysis for removing triphenylmethane derivative

Triphenylmethane (tpm) derivatives (e.g. tpm_CV) have threatened the safety of the aquatic environment due to the potential toxicity and carcinogenicity. In this study, the novel ultrasonic/persulfate/chlorite (US/S₂O₈²⁻/ClO₂⁻) oxidation process was developed for the effective removal of tpm_CV in wastewater. The apparent non-integer kinetics (n around 1.20) of tpm_CV degradation under different factors (R²_Adj > 0.990) were investigated, respectively. Inhibiting effects of anions were greater than those of cations (except Fe(II/III)). The adding of micromolecule organic acids could regulate degradation towards positive direction. The double response surface methodology (RSM) was designed to optimize tpm_CV removal process, and the acoustic-piezoelectric interaction was simulated to determine the propagation process of acoustic wave in the reactor. The possible degradation pathway was explored to mainly include carbonylation, carboxylation, and demethylation. The estimated effective-mean temperature at the bubble-water interface was calculated from 721 to 566 K after introducing the ClO₂⁻, however, the adsorption or partitioning capacity of tpm_CV in the reactive zone was widened from 0.0218 to 0.0982. The proposed co-catalysis of US/S₂O₈²⁻/ClO₂⁻ was based on the determined active species mainly including ClO₂, SO₄⋅⁻, and ⋅OH. Compared with other US-based processes, the operating cost (3.97 $/m³) of US/S₂O₈²⁻/ClO₂⁻ with the EE/O value (16.8 kWh/m³) was relatively reduced.