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The organic compounds contaminated soil substantially threatens the growth of plants and food safety. In this study, we synthesis zero-valent bimetallic Fe/Cu catalysts for the degradation of 2,4-dichlorophenol (DCP) in soils with persulfate (PS) in combination of organic surfactants and exploring the main environmental impact factors. The kinetic experiments show that the wt5% dosage of Fe/Cu exhibits a higher degradation efficiency (86%) of DCP in soils, and the degradation efficiency of DCP increases with the increase of the initial PS concentration. Acidic conditions are favorable for the DCP degradation in soils. More importantly, the addition of Tween-80, and Triton-100 can obviously desorb DCP from the soil surface, which enhances the degradation efficiency of DCP in soils by Fe/Cu and PS reaction system. Furthermore, the Quenching experiments demonstrate that SO 4 ·- and ·OH are the predominant radicals for the degradation of DCP during the Fe/Cu and PS reaction system as well as non-radical also exist. The findings of this work provide an effective method for remediating DCP from soils. © 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd.. All rights reserved.

In the current study, polyaniline and polypyrrole with silicon dioxide (PAni:PPy@SiO2) were combined to formulate a new adsorbent, which was examined using XRD, TEM, SEM, FTIR, TGA, and BET, and the adsorption kinetics were investigated by UV–vis spectroscopy. The optical band gap was also evaluated. The electrochemical behavior was investigated using cyclic voltammograms. Moreover, experimental conditions were used to evaluate the 2,4-dichlorophenol (2,4-DCP) adsorption based on the pH, temperature, reaction time, and initial concentration. The analytical isotherm data were determined by Langmuir, Freundlich, Temkin, Sips, and Redlich–Peterson models. For the analysis of the kinetic data, the pseudo-first- and -second-order models and the intraparticle diffusion model were investigated. It was found that this new adsorbent possessed the highest adsorption efficiency after several regeneration cycles. Furthermore, the thermodynamic parameters of adsorption, such as entropy (ΔS), enthalpy (ΔH), and standard Gibbs were measured. These results suggest that the PAni:PPy backbone can generally be better applied for the elimination of 2,4-dichlorophenol by appropriately dispersing it over the surface of suitable SiO2. This search provides a novel way to develop separable, high-performance adsorbents for adsorbing organic contamination from wastewater.

It has been observed that 2,4-dichlorophenol (2,4-DCP) possesses great environmental concern for its high ecotoxicity and ubiquitousness. Adsorption is one of the simplest methods to remove the 2,4...

Understanding of the plant uptake of ionizable organic compounds is critical to the evaluation of crop contamination, plant protection, and phytoremediation. This study investigated the time-dependent uptake of 2,4-dichlorophenol (DCP) by intact wheat seedling roots and subsequent translocation to shoots at pH 5.0 and 8.0. Sorption of DCP by cut roots and shoots at these two pHs was conducted to provide the uptake limits and the Donnan charge. For comparison, sorption was also conducted for 1,3-dichlorobenzene (DCB), a nonionizable compound having a structure similar to that of DCP. The DCB sorption isotherms were linear and independent of pH, yielding a consistent log Klip of 3.56 with both roots and shoots, reflective of the essential dominant role of lipids in plant partition uptake. Whereas the DCP sorption also showed a linear isotherm at pH 5.0 with log Klip = 2.88, the sorption at pH 8.0 was nonlinear with a concave downward shape, especially at low concentrations. With live wheat seedlings, the DCB uptake by roots and the DCB translocation to shoots rapidly approached a steady state, showing no obvious pH effect. On the DCP uptake by live plants, there was a rapid attainment of a steady state in roots at pH 5.0 coupled with a retarded transport to shoots due presumably to the polarity of DCP. At pH 8.0, the root uptake of DCP was comparatively slower and the translocation to shoots was completely inhibited due presumably to DCP ionization. At high pH, DCP was supposedly accumulated in an ionized form in root cells via an ion-trapping mechanism.

The interactions within microbial, chemical and electronic elements in microbial fuel cell (MFC) system can be crucial for its bio-electrochemical activities and overall performance. Therefore, this study explored polynomial models by response surface methodology (RSM) to better understand interactions among anode pH, cathode pH and inoculum size for optimising MFC system for generation of electricity and degradation of 2,4-dichlorophenol. A statistical central composite design by RSM was used to develop the quadratic model designs. The optimised parameters were determined and evaluated by statistical results and the best MFC systematic outcomes in terms of current generation and chlorophenol degradation. Statistical results revealed that the optimum current density of 106 mA/m2 could be achieved at anode pH 7.5, cathode pH 6.3–6.6 and 21–28% for inoculum size. Anode–cathode pHs interaction was found to positively influence the current generation through extracellular electron transfer mechanism. The phenolic degradation was found to have lower response using these three parameter interactions. Only inoculum size-cathode pH interaction appeared to be significant where the optimum predicted phenolic degradation could be attained at pH 7.6 for cathode pH and 29.6% for inoculum size.

In this study, an amino-functionalized magnetic silica microsphere material (Fe3O4-SiO2-NH2) was prepared. Using glutaraldehyde as a cross-linking agent, Trametes versicolor laccase was adsorbed-co...

The amphiphilic humic acid ester ether (HAEE), as a kind of solid-phase extractant with characteristics of easy separation and hydrophilic-hydrophobic amphiphilic property, was prepared and used to extract micro or trace nitrofen, 2,4-dichlorophenol and p-nitrotrophenol (NIPs) from water and soil. Degradation of NIPs and extractant regeneration were carried out by simple photocatalysis. The adsorption equilibrium of the mono- or three mixed NIPs by HAEE in aqueous could be quickly reached within 20 min. The adsorption process was fit to quasi-second-order kinetics model and Friendlich thermodynamics model. The possible adsorption interaction was discussed. Results suggested that the adsorption of NIPs onto HAEE predominated by hydrogen bonding, hydrophobic interaction and π-π interaction. The extraction capacity of mixed NIPs (80 μg/L each component) by HAEE was up to 0.38 mg/g and tended to be multi-layer adsorption, in which p-nitrotrophenol had higher adsorption competitiveness because of lower resistance to HAEE. When HAEE-NIPs were degraded by photo-catalyst Fe

Sulfate radical based-advanced oxidation process has received increasing interest in the remediation of wastewater and contaminated soil. In this study, degradation of 2, 4-dichlorophenol (2, 4-DCP) was investigated over peroxymonosulfate (PMS) activation by MnO2, which was prepared by liquid-phase oxidation method. The prepared MnO2 was characterized by transition electron microscopy, X-ray diffraction, N2 adsorption–desorption, and X-ray photoelectron spectroscopy. Characterization results showed that α-MnO2 exhibited the highest surface area and Mn (III) content. The PMS activation by MnO2 in 2, 4-DCP degradation followed the order of α-MnO2 > γ-MnO2 > β-MnO2, which is dependent on the properties of MnO2 including crystal structure, surface area and Mn (III) content. Influences of initial concentration of 2, 4-DCP, PMS and MnO2 dosage, pH and co-existing inorganic ions on the degradation were examined. Electron paramagnetic resonance (EPR) and quenching experiments with ethanol and tert-butanol suggested that sulfate radicals were the dominant radicals in the process. Findings in this study indicated that α-MnO2 was an attractive catalyst for activation of PMS to degrade 2, 4-DCP in aqueous solution.

The adsorption of phenol and 2,4-dichlorophenol by diatomite sorbent SMD-Sorb from aqueous solutions is studied. Scanning electron microscopy and energy dispersive X-ray spectral analyses are performed to determine the surface morphology and elemental composition of SMD Sorb diatomite. The specific surface area and total pore volume of the adsorbent are measured via the dynamic low-temperature adsorption of liquid nitrogen. The values of sorption capacity (for phenol and 2,4-dichlorophenol), bulk density, moisture content, and water absorption are estimated. It is shown that the sorbent has fairly low adsorption capacity with respect to the considered substances. The parameters of adsorption equilibria in the surface layers of the studied sorbent are calculated: i.e., the distribution coefficient, limiting adsorption, Henry constants, change in Gibbs energy, adsorption coefficient, and degree of filling, depending on temperature.

In this paper, biochar was modified by cetyltrimethylammonium bromide (CTAB) and KOH solution, and it was characterized by TGA, FT-IR, XRD, BET, SEM. Then, the modified biochar (MB) was used to immobilize free laccase (FL) by adsorption method to prepare modified biochar immobilize laccase (MBL). The adsorption and degradation performance for 2,4-DCP via MB, FL, MBL were studied. The results showed that under the optimal conditions, the adsorption rate of MB on 2,4-DCP was up to 42.5%, adsorption capacity was 85.13 mg/g, and the adsorption of 2,4-DCP by MB was proved to conform to the pseudo-second-order model and the Langmuir adsorption isotherm model; the maximum degradation rate of FL on 2,4-DCP was 97.7%, and the degradation of 2,4-DCP by FL was proved to conform to the first-order kinetic model; under the optimal conditions, the removal rate of MBL on 2,4-DCP can reach almost 100%. MBL combines physical–chemical adsorption and biodegradation, and the contribution of biodegradation is greater than adsorption. Finally, the possible degradation mechanism and pathways of 2,4-DCP were given via high-performance liquid chromatography (HPLC) analysis and gas chromatography-mass spectrometry (GC–MS) analysis.

Nanoscale zero-valent bimetals are receiving considerable attention because of their excellent capability to degrade organic pollutants in water; however, nanoparticle aggregation reduces their reactivity, and the difficult separation limits their general application. Herein, we have developed a novel graphene aerogel anchored nano zero-valent iron and copper (GA-Fe/Cu) composite for the removal of 2,4-dichlorophenol (DCP) through activation by persulfate (PS) under aerobic conditions. The results show that the GA-Fe/Cu aerogel exhibits outstanding performances in the DCP degradation by PS activation, which increase as the Fe/Cu loading increases from 3.1% [GA-Fe/Cu(3.1)] to 9.4% [GA-Fe/Cu(9.4)]. The GA-Fe/Cu(9.4) aerogel exhibits an optimal catalytic activity for DCP degradation (∼100%) by PS activation within 60 min (k1 = 0.0748 min−1). The degradation efficiency of DCP by GA-Fe/Cu(9.4) significantly increases with increasing PS concentration, and slightly decreases from 100% to 80% upon increasing the pH from 4.5 to 9.5. The SO4˙−, ˙OH, and ˙O2− radicals are found to be the dominant reactive oxygen species (ROS) generated by PS activation with GA-Fe/Cu(9.4), while non-radical mechanisms induced by GA appear to be also responsible for the DCP degradation. In addition, 83.2% of DCP is found to be completely mineralized by this reaction system. Thus, the findings of this work provide an alternative route for the efficient removal of organic pollutants from water.

Soil contaminated with pesticides may reduce plant development due to their toxicity. The aim of this study was to evaluate the influence on the germination of Zea mayz and Phaseolus vulgaris of the two main intermediates of the 2,4-D degradation, which are 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP). Maize and bean seeds were treated with distilled water (control treatment) and increased concentrations of 4-CP and 2,4-DCP (0.006, 0.1, 1.0, 1.5 g·L-1). It was assessed seed germination and calculated various parameters. The parameter most affected by chlorophenols was the index of germination rate, being the P. vulgaris seeds most affected. 2,4-DCP was the compound most toxic for both plants. The germination index was dependent doses for both plant models tested. The results indicate that 4-CP and 2,4-DCP affected the index of germination rate but not influenced in other parameters of germination of Zea mayz and Phaseolus vulgaris. Maize was most tolerance to both chlorophenols in the assessed concentrations. 2,4-DCP was the most toxic of chlorophenols tested.

This study demonstrated interesting ultrafast activation of molecular O2 by copper oxide (CuO) particles and very rapid elimination of aqueous 2,4-dichlorophenol (2,4-DCP) within reaction time of 30 s. Electron paramagnetic resonance (EPR) characterization indicated that OH, Cu3+, 1O2 and O2 − were generated in the CuO/O2 systems, wherein O2 − would be the main reactive species responsible for 2,4-DCP degradation. It was further found that the catalytic ability of CuO for O2 activation was highly size dependent and nano-CuO was far reactive than micro-CuO. H2 temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM) analyses revealed that both the quantity and the reactivity of the surface reaction sites (surface Cu+ and O2) could determine the catalytic ability of CuO affecting efficient Cu+-based molecular oxygen activation. Moreover, the O2 activation ability of CuO would depend on not only the dimension, but also crystalline factors, for example, the exposed facets.

In this work, the humic acid (HA)-modified g-C3N4-supported hydrotalcite-like compounds (g-C3N4@HTLcs/HA) was successfully synthesized, characterized, and further applied to remove 2,4-dichlorophen...

A novel fiber optic sensor based on optical composite oxygen-sensitive film was developed for determination of 2,4-dichlorophenol (DCP). The optical composite oxygen-sensitive film consists of tris(2,2′-bipyridyl) dichloro ruthenium(II) hexahydrate (Ru(bpy)3Cl2) as the fluorescence indicator and iron(III) tetrasulfophthalocyanine (Fe(III)PcTs) as bionic enzyme. A lock-in amplifier was used for detecting the lifetime of the composite oxygen-sensitive film by measuring the phase delay of the sensor head. The different variables affecting the sensor performance were evaluated and optimized. Under the optimal conditions (i e, pH 6.0, 25 °C, Fe(III)PcTs concentration of 5.0·10−5 mol/L), the linear detection range, detection limit and response time of the fiber optic sensor are 3.0×10−7–9.0×10−5 mol/L, 4.8×10−8 mol/L(S/N=3), and 220 s, respectively. The sensor displays high selectivity, good repeatability and stability, which have good potentials in analyzing DCP concentration in practical water samples.

Bimetallic Fe/Pd nanoparticles are often used for reductive dechlorination. However, the disadvantage of using bimetallic nanoparticles is their potential aggregation, and hence reduced reactivity....

Covalent organic frameworks have received interest in many fields due to their fascinating properties. In this work, a flower-like covalent organic framework was prepared by a simple solvothermal m...

In present study, a salen-porphyrin complex ZnPSC6 was utilized for improving destruction and detoxification of 2,4-dichlorophenol (2,4-DCP) as it is a binuclear biomimetic complex and has two active sites within one complex as well as high catalytic selectivity and efficiency owing to the combined property of salen complex, porphyrin complex, and biocatalyst. The objectives of the study were to use ZnPSC6 as a catalyst to degrade 2,4-DCP and to study its impact on the toxicity of 2,4-DCP aqueous solution. The conversion of 2,4-DCP was followed by high-performance liquid chromatography (HPLC), liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS), total carbon content (TCC) determination, and ecotoxicity evaluation. Catalysis with ZnPSC6 for 2,4-DCP oxidation by hydrogen peroxide (H2O2) improved the destruction and detoxification of 2,4-DCP in aqueous solution in comparison to salen complex Zn(salen) and porphyrin complex Zn(Phe-TPP). When ZnPSC6 was incorporated into the catalytic oxidation of 2,4-DCP in an aqueous solution of pH 8 at 30°C for 30 min, the conversion of 2,4-DCP was found to be ~100%, very high in comparison to Zn(salen) and Zn(Phe-TPP). A considerable decrease of TCC in 2,4-DCP aqueous solution was observed on adding the ZnPSC6 catalysis compared to Zn(salen) and Zn(Phe-TPP). The TCC values of the ZnPSC6-, Zn(salen)- and Zn(Phe-TPP)-treated 2,4-DCP aqueous solutions were found to be 0.17, 0.51 and 0.42%, respectively. Also, the ecotoxicity of the 2,4-DCP aqueous solution was reduced significantly with ZnPSC6 catalysis. While the ecotoxicity of the 2,4-DCP aqueous solution was 1.14 T.U. after treatment by ZnPSC6 catalysed oxidation, that was 8.18 and 5.53 T.U. for Zn(salen) and Zn(Phe-TPP), respectively. These promotion effects were confirmed in terms of degradation products as determined with LC-TOF-MS. This could suggest a promising process for chlorophenol mineralization.

It is a great challenge for achieving efficiently controllable conversion of chlorinated organics through BiVO4-based photoelectrochemical methods by improving the selective adsorption of such orga...

Chlorinated aromatic compounds (CACs) are a class of persistent organic pollutants, which have serious damage to water environment due to their own stable structure. But a good many of CACs were abandoned because of their tremendous yields and wide applications, so it is urgent to find the effective degradation methods for CACs. The electrochemical method is supposed to be a simple, environmentally friendly and effective pathway to degrade CACs. In this paper, a Pd/GO/Cu composite electrode was prepared by a combination of impregnation method and constant current electrodeposition method, which showed good electrochemical degradation efficiency for the 2,4-dichlorophenol. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface structure, functional group composition, crystal structure and surface element valence of the electrode. Moreover, the stability of the electrode was investigated, and the preparation conditions of the electrode were optimized.

The biocomposites of polypyrrole (PPY), polyaniline (PANI) and sodium alginate (NaAlg) with cellulosic biomass barley husk (BH) were prepared and employed for the removal of 2,4-dichlorophenol (2,4-DCP) form aqueous media. The sorption of 2,4-DCP was studied using native and biocomposites (PPY/BH, PANI/BH and NaAlg/BH) as function of various process variables. The maximum sorption (qe, 7.55–24.57 mg/g) of 2,4-DCP was achieved in the range of 7–10 pH, 0.05 g composite dose, 25 mg/L initial concentration of 2,4-DCP and 120 min contact time at 30 °C. The FTIR analysis revealed the involvement of amino, hydroxyl and carboxylic groups for the binding of 2,4-DCP on the surface of biocomposites. The Freundlich and pseudo second order kinetics models best explained the 2,4-DCP adsorption on to the biocomposites. The ∆G, ∆H and ∆S parameters were also computed, which revealed the favorable and exothermic adsorption nature of 2,4-DCP. Presence of salts affected the 2,4-DCP adsorption negatively. HCl found to be efficient desorbing agent for 2,4-DCP from composites and up to 65.12% was eluted using 0.5 N solution. In view of promising efficiency, the biocomposites have potential to remove 2,4-DCP form industrial effluents.

In the work, the processes of destruction of aqueous solutions of 2,4-dichlorophenol in a dielectric barrier discharge of atmospheric pressure in oxygen were studied. It has been experimentally shown that 2,4-dichlorophenol is destroyed in plasma quite efficiently (the degree of destruction reaches 80 %), which confirms the earlier studies on the decomposition of various organic pollutants in a dielectric barrier discharge plasma. The kinetic parameters were estimated and the main intermediate and final products of the decomposition of 2,4-dichlorophenol under the action of active plasma particles were determined. The destruction of the starting compound is described by a first order kinetic equation. The effective rate constant depends weakly on the experimental conditions and it equals to 0.56 s–1. The composition of the degradation products was studied by gas chromatography, as well as by fluorescence, spectrophotometric and potentiometric methods. Cl- in the liquid phase, as well as СО and СО2 in the gas phase, were identified as the final degradation products. And carboxylic acids and aldehydes were intermediate degradation products. But their concentrations are not high relative to СО and СО2. No molecular chlorine was detected in the gas phase. It was found that ozone does not make a significant contribution to the oxidative destruction of 2,4-dichlorophenol. The hydroxyl radicals and atomic oxygen are main active particles involved in oxidative processes. An increase in the frequency of the discharge current from 50 to 800 Hz, as well as the absence of a hydrophobic coating of the internal electrode, leads to a decrease in the decomposition rate by a factor of 1.7 (from 227 to 135 μmol/(l∙s)).

2,4-Dichlorophenol (DCP) is one of the high-risk sources of contaminating water resources, which is very difficult for biodegradation. In this contribution, sulfonated nickel phthalocyanine (NiPcS) was loaded onto mesoporous KIT-6 through functionalization of the solid support and electrostatic anchorage of the dye. The materials were characterized using standard instrumental methods in every step of the preparation. High catalytic activity was noticed for the degradation of DCP under visible light. The results showed that the photocatalyst had converted nearly 90% of DCP under visible light with optimum operating conditions of 25 mg of catalyst, natural pH (pH 6), and 30 mg L−1 of DCP also, chemical oxygen demand (COD) were determined. The photo-degradation rate of DCP fits well with the pseudo first-order kinetics and, the nonlinear least-squares analysis, which is common for photocatalytic reactions. The catalyst reusing is simple and it was found that it remarkably preserves 94% of its activity following four consecutive cycles of use.

Advanced oxidation processes such as photocatalysis have assumed enormous importance in the scientific field as viable sustainable alternatives to be applied to the elimination of persistent organic pollutants present in water reservoirs for human consumption. Persistent organic compounds like pesticides that belong to the chlorophenol family are a global public health priority since they are associated with serious diseases like cancer and can even cause death at low concentrations of prolonged exposure. This work proposes the use of activated Ni/Al layered double hydroxides as photocatalysts for the degradation of 2,4-dichlorophenol. The study variables associated with the properties of the catalysts were the Ni/Al metal ratio as well as the synthesis conditions. To determine the structural properties of catalytic precursors and catalysts, the techniques of XRD, FTIR, UV-DR, DGTA, TPD, SEM-EDS and TEM were used. The photodegradation tests were carried out in a Bach type reactor with a high energy uv lamp. The results of the photocatalytic degradation of 2,4-dichlorophenol in aqueous solution showed good photocatalytic activity with a degradation efficiency of up to 94% attributed to the presence of Ni in the crystalline and amorphous structures of NiO–NiAl2O4 oxides by means of a combined oxidation-reduction mechanism due to the effect of holes and superoxide and hydroxyl radicals not associated with the memory effect of reconstruction of layered double hydroxides.

In this study, efforts were made to prepare a porous aromatic framework (PAF) with build-in magnetic nanoparticles (Fe3O4-PAF) for use as an efficient adsorbent for the removal of organic pollutants from water. The Fe3O4-PAF showed good handleability and could be recovered easily by magnetic separation. As a proof of concept, the adsorption properties of Fe3O4-PAF were investigated to remove 2,4-dichlorophenol (2,4-DCP) and bisphenol A (BPA) from water. The Fe3O4-PAF showed a fast adsorption rate, high adsorption efficiency and high adsorption capacities. It adsorbed 2,4-DCP (0.1 mmol L-1) and BPA (0.1 mmol L-1) with pseudo-second-order rate constant (k2) of 2.1 and 3.54 g mg-1 min-1, respectively. According to the Langmuir isotherm model, the maximum adsorption capacities of 2,4-DCP and BPA onto Fe3O4-PAF were calculated to be 234.74 and 233.65 mg g-1, respectively. The Fe3O4-PAF also featured good tolerance to harsh conditions, facilitating its application in a real water environment. It could be regenerated easily and reused multiple times without obvious loss of efficiency. In summary, this study provides a general and effective way to improve the handleability of PAFs and expands the practical application of PAF-based materials.

An efficient adsorbent of magnetic activated carbon (Fe3O4@AC) was investigated to remove 2,4-DCP from industrial wastewater samples using a spectrophotometer. The Fe3O4@AC was characterized using ...

Well dispersed SnO2/ZnO composites with platelike shape were synthesized via a facile method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV–Vis diffuse reflectance spectra (UV–Vis DRS) were used to characterize the products. Photocatalytic activity of the as-prepared SnO2/ZnO composites was evaluated by degradation of persistent organic pollutant 2,4-dichlorophenol (2,4-DCP) in aqueous solution. Compared with pure ZnO, SnO2/ZnO composites show higher photocatalytic activity under simulated solar light irradiation. 2,4-DCP is almost completely degraded by SnO2/ZnO composite with molar ratio 1 : 3 within 3.5 h. Moreover, the SnO2/ZnO composites also show excellent circulation stability. The high performance of SnO2/ZnO is mainly attributed to the synergistic effect between SnO2 and ZnO.

It is not only Total Organic Carbon content (TOC) but also the type of Organic Matter (OM) that the sorption of organic pollutants by soils or other natural absorbents is correlated with. Therefore, the characterization of organic components in the adsorbents is very important to elucidate sorption mechanisms.Oil shale samples were collected in Pula, Hungary. The TOC content of the investigated samples was approximately 6.8-40.1 m/m %. The characterization of the organic matter in samples was carried out by using Scanning Electron Microscopy (SEM), elemental analysis, thermal analysis, and GC-MS technics. The results predominantly indicated the presence of a low degree of the branching of aliphatic chain components in the samples. The Humic Substances (HS) content of the samples was only 1-6 m/m %, which could be determined after the treatment of oil shale with hydrogen peroxide.The influence of the amount and type of organic material in oil shale samples was studied on the adsorption of 2,4-dichlorophenol (2,4-DCP) as a model contaminant. For this aim a series of batch equilibration experiments was carried out. The results show that the total organic carbon content of samples is a strong indicator of 2,4-DCP adsorption, while the HS content is an important feature controlling sorption capacity. The study suggests that the special organic matter (kerogen) content of the oil shale plays a major role in its high adsorption capacity and in the nonlinearity of the isotherms. The HS covering the surface could decrease the sorption capacities despite the fact that though the amount of this organic material is quite low.

Various poly(alkylene sulfide)s have been synthesized and used as catalysts to enhance the para-regioselectivity in chlorination of phenol and 2-chlorophenol using freshly distilled sulfuryl chloride in the presence of AlCl3 as an activator. Poly(alkylene sulfide)s having alternating spacers, one having three methylene groups and the second having three, six or nine methylene groups were the most para-regioselective catalysts in chlorination of both phenol and 2-chlorophenol. For example, chlorination of phenol and 2-chlorophenol in the presence of optimal examples of such poly(alkylene sulfide)s gave 4-chlorophenol and 2,4-dichlorophenol as the major products in 94.8 and 95.4% yields, respectively, compared with 75.4 and 55.0% yields in the absence of catalysts. In addition, double chlorination of phenol in the presence of poly(alkylene sulfide)s gave 2,4-dichlrophenol in up to 97.1% yield compared with only 58.6% in the absence of catalysts.

The voltammetric (CV and DPV) behavior of multi-walled carbon nanotube/Nafion composite coupled with a glassy carbon electrode was investigated for the determination of 2,4-dichlorophenol. The structural and morphological evaluation by XRD and FESEM revealed that the acid treated MWCNT retained their morphology without any structural change. The existence of the possible functional groups was investigated by FTIR and Raman spectroscopy. Compared to bare GCE, a significantly reduced interfacial charge transfer resistance was noticed for MWCNT/Nafion/GCE by electrochemical impedance spectroscopy (EIS). The use of Nafion not only contributed to the non-covalent functionalization of MWCNT, but also protected the electrode surface against the polymerization of phenoxy radicals forming a passivating film. For MWCNT/Nafion/GCE, the combination of anti-passivating ability and excellent catalytic properties resulted in the rapid and direct electrochemical determination of 2,4-DCP. Under optimal experimental conditions, the DPV responses for MWCNT/Nafion/GCE is linear over the 1–150 μmol/L range with a detection limit (S/N = 3) of 0.01 μmol/L. The presence of many interfering species had no influence on the signals of 2,4-DCP. The proposed sensor was successfully tested for the determination of 2,4-DCP in tap water samples and the recovery was in the range of 99.0–102.5%. Keywords: 2,4-Dichlorophenol, Electrocatalytic oxidation, Multi-walled carbon nanotube/Nafion composite, Electrochemical sensor, Voltammetry

In this paper, laccase was immobilized with the adsorption-crosslinking method in which biochar was used as the carrier and glutaraldehyde was used as the crosslinking agent. Firstly, the optimal immobilization conditions and optimal operating conditions were investigated, and then the stability of both free laccase and immobilized laccase was compared. Finally, the 2,4-dichlorophenol contaminated soil was remedied with both free laccase and immobilized laccase, and the improvement on the remediation of the contaminated soil by immobilized laccase was analysed through the ecological evaluation. The results showed that in the optimal immobilization condition, the biochar with a particle size of 30 mesh should be selected, and glutaraldehyde with a volume fraction of 4% and 20 mL of laccase solution should be added to complete the 6-hour adsorption operation and 4-hour crosslinking operation. The stability of immobilized laccase was better than that of free laccase, and the thermal deactivation kinetic equation for the free laccase was ln

This study presents the magnetically separable TiO2/FeOx microstructure decorated with poly-oxo-tungstate (POM) leading to the endocrine disruptor 2,4-dichlorophenol (2,4-DCP) under low intensity solar light. The fastest 2,4-DCP degradation kinetics was obtained by way of the TiO2/FeOx(25%)/POM(1%) composite in acidic media. The use of magnetized photocatalysts avoids the high cost separation of the catalysts from the solution by conventional treatments after 2,4-DCP-degradation. Reactive oxygen species (ROS) leading to the 2,4-DCP degradation were identified by use of appropriate scavengers. The 2,4-DCP degradation increased with the applied light intensity (fluence rate) providing evidence for the semiconductor behavior of the composite material. FeOx/Fe2O3 intra-gap states were identified by X-ray photoelectron spectroscopy (XPS) leading to 2,4-DCP degradation. A scheme for the interfacial charge transfer (IFCT) between the oxides is suggested based on the electronic energy position of the oxides making up the photocatalytic composite.

The performance of a hydrolysis acidification + anoxic/aerobic activated sludge (HA+A/O) process under the load shock of 2,4-dichlorophenol (2,4-DCP) was investigated. Results indicated that 2,4-DCP concentration was below 100 mg/L responding to less than 50 mg/L chemical oxygen demand (COD) of HA+A/O effluent. However, further increasing 2,4-DCP concentration from 200 to 500 mg/L subsequently led to the significant reductions of COD removal. The protein-like and humic-like fluorescence intensities of HAHA+A/OA/O effluent increased gradually with 2,4-dichlorophenol concentration from 0.5 to 500 mg/L. 2,4-DCP concentration of HAHA+A/OA/O effluent gradually increased from 1.3 to 475.4 mg/L responding to 2,4-DCP removal rate from 98.8 to 4.5%. Meanwhile, the degradation intermediate products (4-chlorophenol, 4-CP; phenol) of 2,4-DCP were monitored continuously. 4-CP and phenol concentrations reached the highest values of 7.89 mg/L and 5.73 mg/L, respectively with 2,4-DCP concentration 200 mg/L. Based on chloride element conservation equation between influent and effluent, the dichlorination efficiencies decreased from 16.2 to 0.02% with 2,4-DCP concentration from 0.5 to 500 mg/L. In addition, volatile fatty acids (VAF) and oxygen uptake rate (OUR) inhibition rates of HAHA+A/OA/O increased gradually under the load shock of 2,4-dichlorophenol. When 2,4-DCP exceeded 200 mg/L, VAF and OUR inhibited rates were over 50%, respectively. Ultimately, the prediction modelling between biological toxicity and COD removal was established using regression method, which exhibited a good fit (r2 = 0.78). This study could help to predict the effect of 2,4-DCP on the performance of the HAHA+A/OA/O process.

Metal-organic frameworks (MOFs) have unique properties and stable structures, which have been widely used as templates/precursors to prepare well developed pore structure and high specific surface area materials. In this article, an innovative and facile method of crystal reorganization was designed by using MOFs as sacrificial templates to prepare a layered double hydroxide (LDH) nano-layer sheet structure through a pseudomorphic conversion process under alkaline conditions. The obtained CoMn-LDH and CoFe-LDH catalysts broke the ligand of MOFs and reorganized the structure on the basis of retaining a high specific surface area and a large number of pores, which had higher specific surface area and well developed pore structure compared with LDH catalysts prepared by traditional methods, and thus provide more active sites to activate peroxymonosulfate (PMS). Due to the unique framework structure of MOFs, the MOF-derived CoMn-LDH and CoFe-LDH catalysts could provide more active sites to activate PMS, and achieve a 2,4-dichlorophenol degradation of 99.3% and 99.2% within 20 minutes, respectively. In addition the two LDH catalysts displayed excellent degradation performance for bisphenol A, ciprofloxacin and 2,4-dichlorophenoxyacetic acid (2,4-D). X-ray photoelectron spectroscopy indicated that the valence state transformation of metal elements participated in PMS activation. Electron paramagnetic resonance manifested that sulfate radical () and singlet oxygen (1O2) were the main species for degrading pollutants. In addition, after the three-cycle experiment, the CoMn-LDH and CoFe-LDH catalysts also showed long-term stability with a slight activity decrease in the third cycle. The phytotoxicity assessment determined by the germination of mung beans proved that PMS activation by MOF-derived LDH catalysts can basically eliminate the phytotoxicity of a 2,4-D solution. This research not only developed high-activity LDH catalysts for PMS activation, but also expanded the environmental applications of MOF derivants. HIGHLIGHTS LDH derived from MOFs through a pseudomorphic conversion process.; LDH showed excellent activity to activate PMS to degrade 2,4-DCP and other pollutants.; CoMn-LDH and CoFe-LDH exhibited high stability and reusability.; High specific surface area and well developed pore structure of LDH provide more active sites.; Phytotoxicity assessment displayed the practical application value of LDH.

Biotreatment of triclosan is mainly performed in conventional activated sludge systems, which, however, are not capable of completely removing this antibacterial agent. As a consequence, triclosan ends up in surface and groundwater, constituting an environmental threat, due to its toxicity to aquatic life. However, little is known regarding the diversity and mechanism of action of microbiota capable of degrading triclosan. In this work, an immobilized cell bioreactor was setup to treat triclosan-rich wastewater. Bioreactor operation resulted in high triclosan removal efficiency, even greater than 99.5%. Nitrogen assimilation was mainly occurred in immobilized biomass, although nitrification was inhibited. Based on Illumina sequencing, Bradyrhizobiaceae, followed by Ferruginibacter, Thermomonas, Lysobacter and Gordonia, were the dominant genera in the bioreactor, representing 38.40 ± 0.62% of the total reads. However, a broad number of taxa (15 genera), mainly members of Xanthomonadaceae, Bradyrhizobiaceae and Chitinophagaceae, showed relative abundances between 1% and 3%. Liquid Chromatography coupled to Quadrupole Time-Of-Flight Mass Spectrometry (LC-QTOF-MS) resulted in the identification of catabolic routes of triclosan in the immobilized cell bioreactor. Seven intermediates of triclosan were detected, with 2,4-dichlorophenol, 4-chlorocatechol and 2-chlorohydroquinone being the key breakdown products of triclosan. Thus, the immobilized cell bioreactor accommodated a diverse bacterial community capable of degrading triclosan.

In this study, Fe3O4 magnetic nanoparticles (MNPs) were loaded on α-MnO2 nanowires using an improved hydrothermal synthesis method combined with an ultrasonic coprecipitation method, the loading ratio was optimized, the efficiency of the prepared Fe3O4/α-MnO2-activated persulfate (PS) system for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated, and the effects of PS concentration, Fe3O4/α-MnO2 magnetic nanocomposites (MNCs) dosage, pH value and initial pollutant concentration on the degradation of 2,4-DCP were investigated. The results showed that when the initial concentrations of 2,4-DCP, PS, and Fe3O4/α-MnO2 MNCs were 100 mg/L, 30 mmol/L, and 0.4 g/L, the degradation rate of 2,4-DCP reached 96.3% after 180 min of reaction at 30 °C under a neutral condition, and the fitting results showed that the degradation of 2,4-DCP by the Fe3O4/α-MnO2-activated PS system conformed to quasi-first-order kinetics. The degradation of 2,4-DCP by different Fe3O4/α-MnO2-activated PS systems was compared, and a possible PS activation mechanism was proposed. The Fe3O4/α-MnO2 MNCs exhibited excellent reusability, and by introducing Fe3O4/α-MnO2 MNCs as the PS activator into the advanced oxidation process (AOP) system, the electron transfer of Mn(III/IV) and Fe(III/II) on the surface of MNCs was realized, thus greatly improving the reaction efficiency.

MIL-100(Fe), a kind of iron-based metal-organic framework materials (MOFs), can be synthesized at room temperature or hydrothermal conditions, which are promising precursor materials for preparing photocatalysts to degrade some recalcitrant chlorophenols in industrial wastewater. However, the relationship between the structural characterization of MIL-100(Fe) derivatives and their photodegradation behavior of chlorophenol pollutants is still unclear. Thus, in this work, a porous Z-scheme α-Fe2O3/MIL-100(Fe) composite was successfully fabricated via partial-pyrolysis of MIL-100(Fe) precursor synthesized through green synthesis route, which was further used for degrading high-concentration of 2,4-dichlorophenol under visible-light illumination (λ > 420 nm). The effects of synthesis route and pyrolysis temperature of MIL-100(Fe) on the degradation efficiencies of as-derived materials for 2,4-dichlorophenol were investigated. The structure-activity relationship was illuminated in detail. Otherwise, the influence of several process factors, i.e., initial concentration and pH of the 2,4-dichlorophenol solution, catalyst dosage on the degradation efficiency of 2,4-dichlorophenol has also been performed. The removal efficiency of 2,4-dichlorophenol with the initial concentration of 100 mg L−1 reached up to 87.65% under optimized conditions. Lastly, the possible mechanism was explored based on trapping experiments and some other characterization results. The study in this paper not only exhibited new insight into the modified α-Fe2O3 material with high photocatalytic activity but also provided a promising method for treating wastewater containing 2,4-dichlorophenol or other similar organic pollutants.

Using biomass wastes as adsorbents is a promising option for organic waste reclamation, but unfortunately, their adsorption capacity is usually limited, especially for hydrophobic organic pollutants. To address this issue, this work prepared cetylpyridinium chloride (a cationic surfactant)-modified pine sawdust (CPC-PS) and further demonstrated their performance for hydrophobic bisphenol A (BPA) and 2,4-dichlorophenol (DCP) adsorption. Compared to the PS, the CPC-PS improved the maximum adsorption capacity for BPA and DCP by approximately 98% and 122%, respectively. The kinetic and thermodynamic analyses showed that the BPA and DCP adsorption onto the CPC-PS fitted the pseudo-second-order kinetics and the Freundlich model. After regeneration using NaOH, the adsorption capacity of the CPC-PS for BPA still maintained 80.2% of the initial value after five cycles. Based on the experimental results, the CPC-PS was proposed to enhance the BPA and DCP adsorption through the solubilization of hemimicelles for hydrophobic organic pollutants, the π-π stacking between benzene-ring structures, and the hydrogen binding between the adsorbents and the pollutants. This work provides a viable method to use surfactant-modified pine sawdust as effective adsorbents to remove hydrophobic pollutants.

The effects of nitrate on 2,4-dichlorophenol (2,4-DCP) dechlorination and biodegradation in a hydrogen (H2)-based palladized membrane biofilm reactor (Pd-MBfR) were studied. The Pd-MBfR was created by synthesizing palladium nanoparticle (Pd0NPs) that spontaneously associated with the biofilm to form a Pd0-biofilm. Without input of nitrate, the Pd-MBfR had rapid and stable catalytic hydrodechlorination: 93% of the 100-μM influent 2,4-DCP was continuously converted to phenol, part of which was then fermented via acetogenesis and methanogenesis. Introduction of nitrate enabled phenol mineralization via denitrification with only a minor decrease in catalytic hydrodechlorination. Phenol-degrading bacteria capable of nitrate respiration were enriched in the Pd0-biofilm, which was dominated by the heterotrophic genera Thauera and Azospira. Because the heterotrophic denitrifiers had greater yields than autotrophic denitrifiers, phenol was a more favorable electron donor than H2 for denitrification. This feature facilitated phenol mineralization and ameliorated denitrification inhibition of catalytic dechlorination through competition for H2. Increased nitrite loading eventually led to deterioration of the dechlorination flux and selectivity toward phenol. This study documents simultaneous removal of 2,4-DCP and nitrate in the Pd-MBfR and interactions between the two reductions.

With the increasing need for bio-based materials developed by environmentally friendly procedures, this work shows a green method to develop shape-controlled structures from cellulose dissolving pulp coated by chitosan. This material was then tested to adsorb a common and widespread pollutant, 2,4-dichlorophenol under different pH conditions (5.5 and 9). Herein it was noticed that the adsorption only occurred in acidic pH (5.5) where electrostatic interaction drove the adsorption, demonstrating the potential to tune the response under desired conditions only. The adsorption was successful in the hydrogel structure with an adsorption capacity of 905 ± 71 mg/g from a solution with 16.6 ppm; furthermore, adsorption was also possible with dried hydrogel structures, presenting a maximum of adsorption of 646 ± 50 mg/g in a similar 16.6 ppm solution. Finally, adsorbent regeneration was successfully tested for both, dry (rewetted) and never-dried states, showing improved adsorption after regeneration in the case of the never dried hydrogel structures.

The photocatalytic activity of TiO2 nanotubes can be improved through the construction of a Z-scheme composite, where photogenerated electrons from TiO2 recombine with the photogenerated holes in a coupled semiconductor. This arrangement allows for improved oxidation due to the residual holes of TiO2 and better chemical reduction due to the greater availability of the photogenerated electrons of the coupled semiconductor. Efficient Z-scheme porous-g-C3N4/TiO2-nanotube (PCN/TNTs) composites were developed here using a solid sublimation and transition approach, with Al–O links added by an impregnation method to increase interfacial linkages between the PCN and TNTs. The best results for photocatalytic CO2 conversion were obtained using 0.7PCN/0.4Al/TNTs, as shown by production of 54.9 ± 0.70 mg L–1 h–1 of acetic acid, 42.7 ± 0.54 mg L–1 h–1 of formic acid, and 45.4 ± 0.55 mg L–1 h–1 of methanol, which were about 3.8, 4.3, and 4.2 times that produced with bare TNTs. Photocatalytic 2,4-dichlorophenol decompos...

Recently, increasing attention has been paid to the activated peroxymonocarbonate (APMC) process, because it is envisioned to be engineered for the chemical oxidation remediation of groundwater in karstic regions with elevated levels of naturally occurring bicarbonate. In the present study, we explored the feasibility of using metal sulfides (CuFeS2, CuS, and FeS2) as the catalysts for heterogeneous APMC (H-APMC) processes. Among the three synthesized metal sulfides, the CuFeS2 catalyst exhibited reversible redox properties, thereby it had the best performance to activate peroxymonocarbonate (PMC) for the degradation of 2,4-dichlorophenol (2,4-DCP). The X-ray photoelectron spectroscopy analysis and density-functional-theory calculations both revealed that, for the CuFeS2-catalyzed APMC process, iron sites of CuFeS2 acted as the catalytic active sites. Electron spin resonance and chemical quenching experiments revealed that the intermediated reactive species for a CuFeS2-catalyzed APMC process included hydroxyl radicals ( OH), singlet oxygen (1O2), superoxide radicals ( O2−), and carbonate radicals ( CO3−). It was also found that, under a low bicarbonate condition (≤25 mM), the concentration of H2O2 was not the limiting factor that controlled the degradation rate of 2,4-DCP. Instead, bicarbonate concentration and catalyst dosage significantly influenced the performance of CuFeS2-catalyzed APMC process. Al2O3-supported CuFeS2 catalyst (Al2O3@CuFeS2) was prepared and tested as fillers for practical application. The flowing experiment using fixed-bed reactor showed that the Al2O3@CuFeS2 fillers could effectively activate PMC and thereby degraded the 2,4-DCP. Runoff of the coated CuFeS2 component occurred during the experiment, but the leached copper and iron species from the fillers were constantly at a low and safe level (