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Persistent organic pollutants seriously affect the growth and development of crops. 1,2,4-Trichlorobenzene (TCB), as one of the most widely used chlorobenzenes, can affect the yield of japonica rice. However, existing research on the effect of TCB on japonica rice yield is not in-depth, and a basic understanding of commonality has not yet been formed. In this study, 28 conventional japonica rice varieties were selected to investigate the effects of TCB stress on their yield, yield composition, and TCB accumulation. This study also evaluated the efficiency of conventional tolerance indices in evaluating the TCB stress tolerance of japonica rice. The results showed that TCB caused sustained inhibition of the growth of japonica rice, which was considerably manifested in plant height, root length, soil plant analysis development (SPAD), and dry weight at different growth stages. Under TCB stress, TCB accumulation in various tissues of japonica rice increased sharply. TCB stress reduces the yield of japonica rice by reducing the number of panicles per hill, the number of spikelets per panicle, the grain filling percentage, and the grain weight. Overall, the results of this study indicate that TCB stress can cause a decrease in the yield of japonica rice, and the decrease in panicle number is the main reason. The conventional tolerance index can effectively evaluate the tolerance of japonica rice to TCB. The results of this study are substantial for the breeding and cultivation of japonica rice.

The aim: implementation of the principles of green chemistry by regenerating the synthesis solvent 1,2,4-trichlorobenzene and reusing it during the synthesis of the Naphazoline nitrate substance. Study of the influence of the regenerated solvent on the quality of the final product by controlling analytical quality parameters. Development of a method for the quantitative determination and validation of synthesis solvents in a substance. Materials and methods: samples of the substance were synthesized according to the optimized proprietary technology of Farmak JSC. The obtained batches of fresh and regenerated 1,2,4-trichlorobenzene were analyzed according to the monograph of the European Pharmacopoeia on Naphazoline nitrate 0147. Results: the possibility of using regenerated 1,2,4-trichlorobenzene for the synthesis of the substance Naphazoline nitrate has been proven. It is shown that the regenerated solvent does not have a negative effect on the profile of impurities and the polymorphic form of the substance. Analytical quality parameters met the requirements of the internal specification and the requirements of the European Pharmacopoeia monograph. The developed and validated method of quantitative determination of synthesis solvents makes it possible to determine them at the required level. Conclusions: the introduction of regenerated 1,2,4-trichlorobenzene into the synthesis scheme made it possible to significantly reduce the amount of waste per 1 kg of product, which in turn significantly reduced the negative impact on the environment. Analytical quality parameters for regenerated 1,2,4-trichlorobenzene meet the requirements of the internal specification. Industrial series obtained on the regenerated solvent meet the requirements of the monograph of the European Pharmacopoeia. The polymorphic form of the substance batches manufactured on regenerated 1,2,4-trichlorobenzene corresponds to the polymorphic form of the substance batches manufactured on the fresh solvent. The obtained results on the influence of the regenerated solvent on the profile of impurities in the finished substance show the similarity of the profile of the series manufactured on both solvents. According to the requirements of ICH Q3C Impurities: Guideline for residual solvents, a method for quantitative determination of the residual content of 1,2,4-trichlorobenzene in the final product by gas chromatography was developed and validated. The absence of synthesis solvents at the limit of detection is shown. [ABSTRACT FROM AUTHOR]

With the development of modern industry and agriculture, a large amount of 1,2,4-trichlorobenzene (TCB) is being discharged into the environment, which inhibits the growth of rice and threatens food production and food safety. Silicon plays an important role in the process of plants coping with stress, but little is known about the mechanism of silicon regulating TCB tolerance in rice. In this study, two rice varieties with different TCB resistance were studied to explore the alleviating effect and mechanism of silicon on TCB stress in rice. The results showed that silicon alleviated the inhibitory effect of TCB stress on rice growth, which was mainly manifested in that silicon increased the plant height, root length, dry weight and root activity of rice under TCB stress. Silicon alleviated the excessive accumulation of malondialdehyde caused by TCB, which was mainly due to the increase of antioxidant enzyme activity under TCB stress. Similarly, silicon also increases the soluble protein content in rice. In conclusion, silicon enhanced the tolerance of rice to TCB, the performance of rice varieties with different TCB resistance is consistent. This study has guiding significance and theoretical basis for rice production under TCB stress. [ABSTRACT FROM AUTHOR]

The extractive distillation was used to separate ethylbenzene and m-xylene. After the solvent screening, 1,2,4-trichlorobenzene was chosen as the extractive solvent. The vapor–liquid equilibrium (VLE) of binary mixtures of m-xylene, ethylbenzene, and 1,2,4-trichlorobenzene was measured at 101.33 kPa. The measurements were taken with a modified Rose equilibrium still. The Wisniak's test was used to assess the thermodynamic consistency of the VLE experimental results. To obtain the binary interaction parameters, the binary VLE experimental data were correlated with the NRTL, Wilson, and UNIQUAC activity coefficient models. The results showed that three models all fit the experimental values of three binary systems well, and the ternary VLE data of m-xylene + ethylbenzene + 1,2,4-trichlorobenzene were estimated using Aspen Plus V11 based on these model parameters. The experimental data agree well with the estimation values generated from three models. Finally, the effect of 1,2,4-trichlorobenzene as an extractant was analyzed, and it is proved to have a good influence on the separation of ethylbenzene from mixed xylenes by extractive distillation. [ABSTRACT FROM AUTHOR]

In this paper, the separation of the p-xylene and ethylbenzene was explored. The COSMO-SAC-UNIFAC model, σ-profile analysis, solvent power and selectivity were used to screen for a suitable solvent for this process. Then, 1,2,4-trichlorobenzene was selected as target solvent to extract the p-xylene from ethylbenzene. The vapor–liquid-phase equilibrium (VLE) data for binary systems of p-xylene + ethylbenzene, p-xylene + 1,2,4-trichlorobenzene, and ethylbenzene + 1,2,4-trichlorobenzene and ternary system of p-xylene + ethylbenzene + 1,2,4-trichlorobenzene were determined with a modified Rose still at atmospheric pressure (101.3 kPa) and all the binary data passed the Wisniak's test, which accorded with the thermodynamic consistency. Three thermodynamic models, Wilson, NRTL and UNIQUAC were used to correlate the VLE data and get binary interaction parameters, then the ternary VLE data of p-xylene + ethylbenzene + 1,2,4-trichlorobenzene were estimated based on these model parameters using Aspen Plus V10. The estimation values of the three models are in good agreement with the experimental data. Moreover, the effect of 1,2,4-trichlorobenzene was analyzed and it was found to be an effective candidate extractant for the extractive distillation of ethylbenzene from mixed xylenes. [ABSTRACT FROM AUTHOR]

Intimate coupling photocatalysis and biodegradation treatment technology is an emerging technology in the treatment of refractory organic matter, and the carrier plays an important role in this technology. In this paper, sugarcane cellulose was used as the basic skeleton, absorbent cotton was used as a reinforcing agent, anhydrous sodium sulfate was used as a pore-forming agent to prepare a cellulose porous support with good photocatalytic performance, and nano-TiO2 was loaded onto it by a low-temperature bonding method. The results showed that the optimal preparation conditions of cellulose carriers were: cellulose mass fraction 1.0%; absorbent cotton 0.6 g; and Na2SO4 60 g. The SEM, EDS and XPS characterization further indicated that the nano-TiO2 was uniformly loaded onto the cellulose support. The degradation experiments of Rhodamine B showed that the nano-TiO2-loaded composite supports had good photocatalytic performance. The degradation rate of 1,2,4-trichlorobenzene was more than 92% after 6 cycles, and the experiment of adhering a large number of microorganisms on the carriers before and after the reaction showed that the cellulose-based carriers obtained the required photocatalytic performance and stability, which is a good cellulose porous carrier. [ABSTRACT FROM AUTHOR]

Persistent organic pollutants seriously affect the growth and development of crops. 1,2,4-Trichlorobenzene (TCB), as one of the most widely used chlorobenzenes, can affect the yield of japonica rice. However, existing research on the effect of TCB on japonica rice yield is not in-depth, and a basic understanding of commonality has not yet been formed. In this study, 28 conventional japonica rice varieties were selected to investigate the effects of TCB stress on their yield, yield composition, and TCB accumulation. This study also evaluated the efficiency of conventional tolerance indices in evaluating the TCB stress tolerance of japonica rice. The results showed that TCB caused sustained inhibition of the growth of japonica rice, which was considerably manifested in plant height, root length, soil plant analysis development (SPAD), and dry weight at different growth stages. Under TCB stress, TCB accumulation in various tissues of japonica rice increased sharply. TCB stress reduces the yield of japonica rice by reducing the number of panicles per hill, the number of spikelets per panicle, the grain filling percentage, and the grain weight. Overall, the results of this study indicate that TCB stress can cause a decrease in the yield of japonica rice, and the decrease in panicle number is the main reason. The conventional tolerance index can effectively evaluate the tolerance of japonica rice to TCB. The results of this study are substantial for the breeding and cultivation of japonica rice., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Yan, Zhang, Liu, Wang, Zhao, Huang and Niu.)

Two strains were isolated, Achromobacter sp. NE1 (GenBank MW132988) and Brevundimonas sp. 242 (GenBank MW132989), which possessed a unique ability to use lindane and the intermediates of its a-erobic biotransformation, 1,2,4-trichlorobenzene (strain NE1) and 2,5-dichlorophenol (strain 242) as a sole source of carbon and energy. The strains were found to contain the linA gene encoding dehydrochlorinase, the first enzyme of lindane degradation, exhibiting 99.65–100% sequence identity to the linA genes of Sphingobium degrader strains. [ABSTRACT FROM AUTHOR]

Intimate coupling photocatalysis and biodegradation treatment technology is an emerging technology in the treatment of refractory organic matter, and the carrier plays an important role in this technology. In this paper, sugarcane cellulose was used as the basic skeleton, absorbent cotton was used as a reinforcing agent, anhydrous sodium sulfate was used as a pore-forming agent to prepare a cellulose porous support with good photocatalytic performance, and nano-TiO2 was loaded onto it by a low-temperature bonding method. The results showed that the optimal preparation conditions of cellulose carriers were: cellulose mass fraction 1.0%; absorbent cotton 0.6 g; and Na2SO4 60 g. The SEM, EDS and XPS characterization further indicated that the nano-TiO2 was uniformly loaded onto the cellulose support. The degradation experiments of Rhodamine B showed that the nano-TiO2-loaded composite supports had good photocatalytic performance. The degradation rate of 1,2,4-trichlorobenzene was more than 92% after 6 cycles, and the experiment of adhering a large number of microorganisms on the carriers before and after the reaction showed that the cellulose-based carriers obtained the required photocatalytic performance and stability, which is a good cellulose porous carrier.

Abstract A home-made analytical instrument based on thermal desorption gas chromatography coupled to resonance enhanced multiphoton ionization time-of-flight mass spectrometry (TD-GC-REMPI-TOFMS) was applied for atline measurement of 1,2,4-trichlorobenzene for the prediction of polychlorinated dibenzodioxin and dibenzofuran (PCDD/F) concentrations in the stack gas of a municipal solid waste incinerator (400 ton/day). Conventional high resolution gas chromatography/high resolution mass spectroscopy (HRGC/HRMS) measurements for the determination of PCDD/F concentrations were performed to compare with TD-GC-REMPI-TOFMS measurements. 1,2,4-Trichlorobenzene correlated with I-TEQ at r = 0.867, 0.953 and 0.944 in unstable, stable and integrated conditions. The correlation was independent of the facility operating conditions observed in this study. Using a linear model to predict I-TEQ by 1,2,4-trichlorobenzene over the test, the average of the relative difference between predicted and measured I-TEQ was 18.9%. 1,2,4-Trichlorobenzene measured by TD-GC-REMPI-TOFMS can be used as a robust indicator of I-TEQ in stack gas. Graphical abstract Image 1 Highlights • Correlation between 1,2,4-Cl 3 Bz and I-TEQ was independent of incinerator conditions. • Lower-range data was crucial to correlations. • I-TEQ prediction post APCDs was more accurate than that prior to APCDs. Robust correlations between I-TEQ and 1,2,4-Cl 3 Bz were found in waste incineration stack gas. 1,2,4-Cl 3 Bz measured by TD-GC-REMPI-TOFMS could be used to predict I-TEQ. [ABSTRACT FROM AUTHOR]

1,2,4-Trichlorobenzene (1,2,4-TrClBz) as dioxin indicator in municipal solid waste incineration can increase risk of human health. Aerobic denitrifying membrane biofilm reactor (MBfR) was investigated for 1,2,4-TrClBz removal in flue gas. During the 75 days of operation, 1,2,4-TrClBz removal efficiency achieved 94%. Pseudomonas , Halomonas , Paracoccus , Thauera , Azoarcus , Proteiniphilum , Mesorhizobium , Pelagibacterium , Chelativorans were the core 1,2,4-TrClBz biodegrading-denitrifying bacteria. 1,2,4-TrClBz biodegradation genes and denitrification genes were responsible for the oxidation of 1,2,4-TrClBz and nitrate reduction. 1,2,4-TrClBz was degraded by ring-cleavage before aerobic dechlorination, 1,2,4-TrClBz bio-oxidation was coupled to denitrification formed redox between 1,2,4-TrClBz and nitrate, as shown by metagenomic sequencing and untargeted metabolomic analysis. Therefore, MBfR effectively achieved bioremoval and biodegradation of 1,2,4-TrClBz in flue gas by aerobic denitrification, which may provide a feasible and environment-friendly biotechnique for decontamination of chlorobenzene compounds in flue gas. • Aerobic denitrifying MBfR achieved removal of 1,2,4-trichlorobenzene in flue gas. • Pseudomonas , Halomonas , Paracoccus , Thauera were the core 1,2,4-trichlorobenzene biodegrading-denitrifying genus. • 1,2,4-trichlorobenzene was biodegraded by ring-cleavage before aerobic dechlorination. • 1,2,4-trichlorobenzene bio-oxidation was couple to denitrification. [ABSTRACT FROM AUTHOR]

A selected set of new 4H-benzothiopyran-4-one derivatives 6a-h has been prepared by a one-pot reaction involving deprotonated methyl 3-oxo-3(2',4',5'-trichlorophenyl)propanoate 5 and the appropriate aryl or alkyl isothiocyanate. 2,4,5-Trichloroacetophenone 4, required for the synthesis of 5, is successfully prepared by Friedel-Craft's acetylation of 1,2,4-trichlorobenzene in 82% yield. The structures of the new compounds 5 and 6a-h are based on microanalytical and spectral (NMR, MS(EI), and HRMS) data. [ABSTRACT FROM AUTHOR]

Dehalobacter sp. strain TeCB1 was isolated from groundwater near Sydney, Australia, that is polluted with a range of organochlorines. The isolated strain is able to grow by reductive dechlorination of 1,2,4,5-tetrachlorobenzene to 1,3- and 1,4-dichlorobenzene with 1,2,4-trichlorobenzene being the intermediate daughter product. Transient production of 1,2-dichlorobenzene was detected with subsequent conversion to monochlorobenzene. The dehalogenation capability of strain TeCB1 to respire 23 alternative organochlorines was examined and shown to be limited to the use of 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene. Growth on 1,2,4-trichlorobenzene resulted in the production of predominantly 1,3- and 1,4-dichlorobenzene. The inability of strain TeCB1 to grow on 1,2-dichlorobenzene indicated that the production of monochlorobenzene during growth on 1,2,4,5-tetarchlorobezene was cometabolic. The annotated genome of strain TeCB1 contained only one detectable 16S rRNA gene copy and genes for 23 full-length and one truncated Reductive Dehalogenase (RDase) homologs, five unique to strain TeCB1. Identification and functional characterization of the 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene RDase (TcbA) was achieved using native-PAGE coupled with liquid chromatography tandem mass spectrometry. Interestingly, TcbA showed higher amino acid identity with tetrachloroethene reductases PceA (95% identity) from Dehalobacter restrictus PER-K23 and Desulfitobacterium hafniense Y51 than with the only other chlorinated benzene reductase [i.e., CbrA (30% identity)] functionally characterized to date. [ABSTRACT FROM AUTHOR]

Montmorillonite–TiO2 nanocomposites were prepared using two different methods (ultrasonic or stirring) and using titanium(IV) isopropoxide as precursor. The solids were characterized by element chemical analysis, X-ray diffraction, FTIR spectroscopy, thermal analyses, and nitrogen adsorption. The evolution of the properties as a function of the preparation method was discussed. These nanocomposites were used as catalysts for the photodegradation of 1,2,4-trichlorobenzene. The degradation pathway and the nature of the by–products were investigated by mass spectrometry.

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The natural attenuation of 1,2,4-trichlorobenzene (1,2,4-TCB) in shallow aquifer was investigated at the Luhuagang's landfill site (LLS), where the subsoil and shallow aquifer have been contaminated by certain chemicals owning to a lack of protective structures and leachate collection systems. Batch natural attenuation experiments and molecular biology experiments were conducted to study the natural attenuation characteristics of 1,2,4-TCB, the relative contributions of the primary natural attenuation processes and the functional microorganisms degrading 1,2,4-TCB, respectively. The results indicated that the relationship between degradation rate and 1,2,4-TCB concentrations was in line with first-order decay kinetics, and the natural attenuation rate of 1,2,4-TCB in the three media followed the order silt > fine sand > medium sand, which was related to the size of the media and the microbial population. The relative contribution of adsorption to natural attenuation was 97.7%, 98.2%, and 95.7% in unsterilized silt, fine sand and medium sand, respectively, and that of biodegradation was 2.3%, 1.8%, and 4.3%, respectively. These properties are related to the characteristics of the pollutants and the specific conditions at the contaminated sites, such as the characteristics of the aquifer media and microbial communities. The functional microorganisms degrading 1,2,4-TCB at the site were proved to be primarily Pseudomonas sp. This study indicates the feasibility of bioremediation (bioaugmentation and biostimulation) by indigenous microorganisms to treat 1,2,4-TCB contamination at the site. [ABSTRACT FROM AUTHOR]

The Luhuagang landfill site (LLS) in Kaifeng, China, lacks liner and leachate collection systems. Thus, leachate generated from the waste dump has contaminated the surrounding subsoil and shallow aquifer with various chemicals, including 1,2,4-Trichlorobenzene (1,2,4-TCB). This paper is a part of a series of studies on adsorption, transport and biodegradation and fate of 1,2,4-TCB in the shallow aquifer beneath LLS. Here, adsorption of 1,2,4-TCB onto silt, fine sand and medium sand aquifer deposits collected at LLS was conducted by performing batch experiments involving four common adsorption kinetic models. The results of the analyses showed that the pseudo-second-order adsorption kinetic model provided the best fit for the equilibrium data with a coefficient of determination ( R) greater than 0.99. Least squares analysis of Henry, Freundlich and Langmuir linearly transformed isotherm models was used to establish the best isotherm for 1,2,4-TCB adsorption onto the three aquifer materials. The Freundlich isotherm provided the best fit for experimental data with R > 0.99. The results further suggested that the highest adsorption rate of 1,2,4-TCB (27.55 μg/g) was onto silt deposit, followed by fine sand (21.65 μg/g) and medium sand (14.88 μg/g). This showed that silt layer beneath the LLS was critical for retarding the downward percolation and migration of 1,2,4-TCB into the shallow aquifer systems under the landfill. The findings of the study were adopted as basis for designing the slated transport and biodegradation study of 1,2,4-TCB in aquifer system at LLS. [ABSTRACT FROM AUTHOR]

Highlights: [•] During 1,2,4-TCB mineralization signal molecules are produced. [•] Microbial communities attached on a carrier establish a cell-to-cell communication. [•] Efficient cell-to-cell communication results in high 1,2,4-TCB mineralization. [•] Quantity and quality of signaling molecules depend on the type of inoculation. [•] Cell-to-cell communication occurs via interspecies communication. [Copyright &y& Elsevier]

Eisenia fetida was tested to assess terrestrial ecotoxicity in microcosms contaminated by copper (Cu), lead (Pb), and 1,2,4-trichlorobenzene (TCB) separately and in combinations. Toxicity endpoints were the median lethal concentration (LC50) and acid phosphatase (ACP), adenosine triphosphatase (ATPase), and glutathione S-transferase (GST) activities. Single toxicity tests revealed that the toxicity order was 1,2,4-TCB>Cu>Pb for E. fetida with LC50 as the toxicity criterion. A binary combination of Cu (25 or 200 mg/kg) and TCB (25 or 200 mg/kg) caused increased ACP and ATPase activities but decreased GST activities in all treatments. A combination of Pb (50 or 400 mg/kg) and TCB (50 or 400 mg/kg) caused increased (days 2 and 14) and decreased (day 7) ACP activities, initially increased (day 2) and then decreased (days 7 and 14) ATPase activities, and decreased GST activities in all treatments. In general, antagonistic and/or synergistic responses reflected bioaccumulation patterns in some binary combinations, but patterns in mixtures were not always consistent with toxicity data. This work presented in the article is original and novel and the results of this work can be regarded as sensitive parameters for monitoring the contamination in soils. [ABSTRACT FROM AUTHOR]

Abstract: A micrometer-sized, nanostructured, flower-like Co3O4–CeO2 composite oxide was synthesized by an ethylene-glycol-mediated process. The composite oxide was an assembly of polycrystalline nanoparticles, with a typical mesoporous structure. The composite''s catalytic activity in 1,2,4-trichlorobenzene degradation was evaluated using a pulsed-flow microreactor–gas chromatography system, and compared with that of quartz sand, commercial CeO2, commercial Co3O4, and a Co3O4/CeO2 equimass mixture. The composite oxide was a promising catalyst for 1,2,4-trichlorobenzene degradation. This is attributed to the structural features of the composite oxide with a high specific surface area and a high total pore volume, and the synergistic effect between the two composite phases. The easy creation of high-mobility active oxygen on CeO2 and the easy cleavage of Cot the interface of the two components promote reactivity of Co3O4 in 1,2,4-trichlorobenzene degradation. Pulsed catalytic theory suggests a first-order reaction between the composite oxide and 1,2,4-trichlorobenzene, with an apparent activation energy of about 27kJ/mol, and degradation on the Co3O4–CeO2 composite oxide would occur easily. [Copyright &y& Elsevier]

Abstract: Hydrodechlorination of 1,2,4-trichlorbenzene was carried out over ruthenium catalysts supported on γ-Al2O3, CeO2, ZrO2, SiO2, SBA-15 and activated carbon. In the hydrodechlorination of 1,2,4-trichlorobenzene, higher catalytic activities and longer catalyst life was achieved for Ru catalysts supported on carbon compared to Ru catalysts supported on other supports. The higher catalytic activity exhibited by carbon supported ruthenium catalysts was attributed due to high dispersion of Ru, metal area and smaller crystallite size owing to strong chemisorption of 1,2,4-trichlorobenzene leading to complete hydrodechlorination. [Copyright &y& Elsevier]

Abstract: Co3O4 was synthesized with cabbage-like, plate-like and sphere-like morphologies. The effect of different morphologies on the degradation of 1,2,4-trichlorobenzene (1,2,4-TrCB) was evaluated, and the cabbage-like Co3O4 exhibited the highest reactivity. The degradation of 1,2,4-TrCB on the cabbage-like Co3O4 is hypothesized to act competitively via hydrodechlorination and oxygen-attacking pathways. By the hydrodechlorination pathway, 1,2,4-TrCB is successively dechlorinated into the three dichlorobenzenes (DCBs) and then monochlorobenzene (MCB). The yield of the DCBs was in the order of p-DCB> m-DCB> o-DCB, which can be explained by the calculated C–Cl bond dissociation energies in 1,2,4-TrCB and DCBs. Derivatization and electron spin resonance experiments identified that lattice oxygen and superoxide anions may take part in the oxidation pathway. The lattice oxygen initiated a partial oxidation of 1,2,4-TrCB, leading to the formation of chlorinated phenols. The superoxide anions caused ring-cracking oxidation of 1,2,4-TrCB, possibly producing some low-molecular-weight products, thus explaining a mass imbalance in the chlorine atoms and total organic carbon. [Copyright &y& Elsevier]

Abstract: Alkali-modified Pd (wt%)/HT catalysts, where HT is calcined Mg/Al hydrotalcite (Mg(Al)O), were studied for the HDC reaction of 1,2,4-trichlorobenzene at mild conditions (atmospheric pressure and 373K) using a continuous reactor. Characterization of the alkali-modified Pd/HT catalysts by H2-chemisorption, N2-physisorption, SEM, HRTEM and CO2-TPD analysis revealed different textural, metallic and basic properties depending on the type of alkaline metal and precursor. The hydrodechlorination reaction of 1,2,4-trichlorobenzene was strongly dependent on the type of alkaline additives (Li, Na or Cs) and alkaline precursors (OH− or NO3 −). The basic properties of the catalysts showed a predominant role in activity, selectivity and stability of the catalysts. Furthermore the HDC catalytic activity is highly dependent in the intrinsic property of alkali metal species. The affinity of the chloride produced during the reaction to the strong basic alkali surface contributes for the higher stability of the alkali-modified catalyst. Calcination–reduction and reduction treatments were employed to regenerate the catalyst. The initial catalytic activity was recovered when the used sample was regenerated by reduction treatment. [Copyright &y& Elsevier]

Abstract: Molecular dynamics simulations have been carried out to assess event details in the adsorption of the hydrophobic substrate 1,2,4-trichlorobenzene (TCB) on the hydrophilic TiO2 particle surface in the presence of the biosurfactant 4-O-(4′,6′-di-O-acetyl-2′,3′-di-O-alkanoyl-β-d-mannopyranosyl)-d-erythritol (MEL) and the SDS (sodium dodecylsulfate) surfactant in aqueous media at ambient temperature with interaction forces between organic molecules and TiO2 calculated from Lennard–Jones and Coulomb potential models. The surfactant and the TCB substrate were arranged in the vicinity of TiO2 using 768 water molecules in the simulations. Results indicate that the MEL molecules adsorb on the TiO2 surface in ca. 5ps (k =2×1011 s−1) through the oxygen atoms of the hydrophilic functions. Contact distance between the MEL and the TiO2 surface shortened further after 10ps with adsorption controlled mostly by van der Waals’ forces. The TCB molecules are trapped within the alkyl chains of the MEL system, which subsumes TCB to a greater extent by the repulsion of water, thereby facilitating the TCB molecules to approach the highly hydrophilic and positively charged TiO2 particle surface. Along with the simulations, also examined was the photodegradation of this hydrophobic TCB substrate that takes place at the TiO2/water interface in the presence of the MEL biosurfactant. For comparison, the advantages of the MEL in this task and of the commonly used SDS surfactant were determined under otherwise identical experimental conditions (200mgL−1 of surfactants) by examining the dynamics of the photo-induced degradation and dechlorination of TCB. The photodegradation of TCB was nearly quantitative in MEL/TiO2 in contrast to only ca. 22% complete in SDS/TiO2 dispersions. It is deduced that wastewater treatments with the highly hydrophilic TiO2 are seriously limited in their photodegradation of hydrophobic pollutants, an issue easily resolvable by the presence of biodegradable surfactants. [Copyright &y& Elsevier]

Fly ash, industry lime and an additive, Ca(ClO2 )2 (C) were used to prepare the 'oxygen-enriched' highly active absorbent (HAA). The influencing factors for removal of 1,2,4-trichlorobenzene (TCB) using this absorbent such as reaction temperature, simulating gas flow rate, oxygen content, etc. were studied in a self-designed reactor. The optimum experimental conditions of removing 1,2,4-TCB are that the content of an oxidizing additive in the absorbent is 3% (wt), simulating gas flow rate is 100 mL/min, reaction temperature is 250°C, and the content of oxygen in simulating gas is 6%. The maximum removal efficiency is 81.71% in 10 mins. The absorption capacity of the absorbent is 0.000111 g/g. The reaction products were determined by gas chromatograph/mass spectrometer (GC/MS), 2,6-Bis-[1,1-Dimethylethyl]-4-methyl-Phenol is considered to be the major intermediate product. The reaction route was revealed. [ABSTRACT FROM AUTHOR]

Synthesis and kinetics of dichloro-methoxybenzenes were studied from 1,2,4-trichlorobenzene and sodium methoxide in a temperature range of 353–383 K. Effects of molar ratio of reactants, solvent and reaction temperature were investigated. Reaction products include three isomers. The order of selectivity for the three isomers was 1,4-dichloro-2-methoxybenzene>>2,4-dichloro-1-methoxybenzene>1,2-dichloro-4-methoxybenzene. Kinetic equations for the parallel liquid-solid interface reaction between 1,2,4-trichlorobenzene and sodium methoxide were established in the absence of catalyst. Kinetic parameters such as the pre-exponential factors and the activation energy were determined with the Arrhenius equation. [ABSTRACT FROM AUTHOR]

Abstract: Catalytic hydrodechlorination (HDC) is an efficient way to remove chloride species from chlorinated hydrocarbons. Hydrodechlorination reaction of 1,2,4-trichlorobenzene was studied over a series of palladium (1wt.%) catalysts supported on calcined Mg/Al hydrotalcite-like materials (HT) prepared with different Mg/Al ratios. The fresh catalysts were characterized using ICP-OES, XRD, N2-physisorption, H2-chemisorption, TPR, and TEM. It has been observed that the activity, stability and selectivity of the catalysts in the hydrodechlorination reaction of 1,2,4-trichlorobenzene were strongly dependent on the Mg/Al molar ratio in the Mg(Al)O support. The sample with Mg/Al ratio of 4 exhibited the highest activity and selectivity towards total hydrodechlorination reaction giving benzene. Rehydration of the calcined hydrotalcite catalyst resulted in an enhancement of the hydrodechlorination performance. The spent samples were characterized by TPO/MS, TGA and ESEM–EDS techniques. Based on our results it was revealed that catalyst deactivation was mainly due to coke formation. The amount of coke decreased with the base character of the support. The amount of coke formed during the reaction can be eliminated by combustion recovering the initial activity. [Copyright &y& Elsevier]

Abstract: A series of Ru/Nb2O5 catalysts with Ru loadings from 0.5–7.18wt.% were prepared and characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption (TPD) of hydrogen and CO chemisorption measurements. XRD patterns reveal the presence of RuO2 from 3.0wt.% Ru loading. TPR profiles show only one peak due to reduction of RuO2 to Ru0. The H2-TPD exhibits two peaks, one due to desorption of hydrogen from Ru metal and another due to spill over from metal to the support. The catalytic properties were evaluated for the vapor-phase hydrodechlorination of 1,2,4-trichlorobenzene and related to Ru dispersion. [Copyright &y& Elsevier]

The genetic information encoding metabolic pathways for xenobiotic compounds in bacteria often resides on catabolic plasmids. The aim of the present work was to know the location of the genes for degrading 1,2,4-trichlorobenzen. In this paper a 1,2,4-trichlorobenzene-degrading strain THSL-1 was isolated from the soil of Tianjin Chemical Plant using 1,2,4-trichlorobenzene as the sole carbon source. The strain was identified as Pseudomonas stutzeri through morphologic survey and 16S rDNA sequence determination. A plasmid was discovered from strain THSL-1 by using the alkali lysis method. When the plasmid was transformed into E. coli. JM109 by the CaCl2 method, the transformant could grow using 1,2,4-trichlorobenzene as the sole carbon source and had the degradation function of 1,2,4-trichlorobenzene. Therefore, it could be deemed that the plasmid carried the degradative genes of 1,2,4-trichlorobenzene. The average size of the plasmid was finally determined to be 40.2 Kb using selectively three kinds of restricted inscribed enzymes ( HindIII, BamHI, and XholI) for single cutting and double cutting the plasmid pTHSL-1, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The effects of 5 mg/L 1,2,4-trichlorobenzene (TCB) and 0.1 mmol/L mercury ion (Hg2+) stresses on Ca2+ fluxion and protein phosphorylation in rice seedlings were investigated by isotope exchange kinetics and in vitro phosphorylation assay. The Ca2+ absorption in rice leaves and Ca2+ transportation from roots to leaves were promoted significantly in response to Hg2+ and TCB treatments for 4-48 h. The Ca2+ absorption peaks presented in the leaves when the rice seedlings were exposed to Hg2+ for 8-12 h or to TCB for 12-24 h. Several Ca2+ absorption peaks presented in the roots during rice seedlings being exposed to Hg2+ and TCB, and the first Ca2+ absorption peak was at 8 h after being exposed to Hg2+ and TCB. The result of isotope exchange kinetic analysis confirmed that short-term (8 h) Hg2+ and TCB stresses caused Ca2+ channels or pumps located on plasmalemma to open transiently. The phosphorylation assay showed that short-term TCB stress enhanced protein phosphorylation in rice roots (TCB treatment for 4-8 h) and leaves (TCB treatment for 4-24 h), and short-term (4-8 h) Hg2+ stress also enhanced protein phosphorylation in rice leaves. The enhancement of protein phosphorylation in both roots and leaves corresponded with the first Ca2+ absorption peak, which confirmed that the enhancement of protein phosphorylation caused by TCB or Hg2+ stress might be partly triggered by the increases of cytosolic calcium. TCB treatment over 12 h inhibited protein phosphorylation in rice roots, which might be partly due to that TCB stress suppressed the protein kinase activity. Whereas, Hg2+ treatment inhibited protein phosphorylation in rice roots, and Hg2+ treatment over 12 h inhibited protein phosphorylation in rice leaves. This might be attributed to that not only the protein kinase activity, but also the expressions of phosphorylation proteins were restrained by Hg2+ stress. [Copyright &y& Elsevier]

Abstract: A risk assessment on 1,2,4-trichlorobenzene was carried out specifically for the marine environment according to the methodology laid down in the EU Risk Assessment Regulation 1488/94 and the Guidance Documents of the EU Existing Substances Regulation 793/93. The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentrations (PNEC) for the marine aquatic environment. A PNECwater value of 0.3μg/l and a PNECsed value of 38μg/kgdw were derived from the results of toxicological studies in organisms representing three trophic levels, i.e. aquatic plants, invertebrates and fish. Based on monitoring data two situations are distinguished: a typical case and a worst case with a PECwater of <0.047 and 0.1μg/l, respectively, and a PECsed of 40 and 90μg/kgdw, respectively. The calculated PEC/PNEC ratios were 0.16 and 0.3 for water and 1 and 2.4 for sediment, respectively. It was concluded that no risks are expected for aquatic organisms. Based on the combination of worst-case assumptions risks to benthic organisms could not be fully excluded, but since all open uses of 1,2,4-trichlorobenzene will be ended following the EU risk assessment outcome of 2001 any potential risk is expected to be reduced accordingly. 1,2,4-trichlorobenzene is not considered toxic according to the EU criteria and the available data on persistence of 1,2,4-trichlorobenzene indicate a half-life in water of a few days and a significant biodegradation potential. The bioaccumulation potential is low to moderate with most BCF ratios for fish ranging from 600 to 1400 and one highest of 2020. Based on an extensive evaluation of persistence, biodegradation and bioaccumulation data it is concluded that 1,2,4-trichlorobenzene is not a PBT, since it does not fulfill any of the EU criteria. Biomagnification in the food chain is not expected due to the relatively high elimination rate constants. [Copyright &y& Elsevier]

In laboratory experiments the mineralisation of 14C-labelled 1,2,4-trichlorobenzene (1,2,4-TCB) in soils was studied by direct measurement of the evolved 14CO2. The degradation capacity of the indigenous microbial population was investigated in an agricultural soil and in a soil from a contaminated site. Very low mineralisation of 1% within 23 days was measured in the agricultural soil. Whereas in the soil from the contaminated site the mineralisation occurred very fast and in high rates; up to 62% of the initially applied amount of 1,2,4-TCB were mineralised within 23 days. The transfer of the adapted microbial population into the agricultural soil significantly enhanced the mineralisation of 1,2,4-TCB in this soil, reflecting, that the transferred microbial population survived and maintained its degradation ability in the new microbial ecosystem. Additional nutrition sources ((NH4)2HPO4) increased the mineralisation rates in the first days significantly in the contaminated soil. In the soil from the contaminated site high amounts of non extractable 14C-residues were formed. [Copyright &y& Elsevier]

Unusual regiochemistry is observed in the products arising from the reaction of lithiated 1,2,4-trichlorobenzene with N,N-dimethylformamide and tetraalkyloxamides. [Copyright &y& Elsevier]

Several Ni/Al-MCM-41 catalysts were tested in the gas phase hydrodechlorination of 1,2,4-trichlorobenzene at atmospheric pressure. They showed high activity and selectivity towards benzene at reaction temperatures between 473 and 523 K with values of 100% conversion and 100% benzene selectivity at 523 K for all of them. [ABSTRACT FROM AUTHOR]