P-chloroaniline Research Articles

Dipole Moment Studies in some Substituted Anilines with Alcohols

Dipole moments have been determined by using the mixtures of diluted solutions of aniline, o-chloro aniline, p-chloro aniline, ethanol, 2-butoxy ethanol and 2-methoxy ethanol in carbon tetrachloride at 30° C based on Debye’s polarization method and Huysken’s method. The results are interpreted that the complex dipole moment for the halogen substitution of acceptor complexes is greater than the mono substituted acceptor complexes. But the case is reversed in halogen substitution of donor complexes.

Compound specific isotope analysis to characterize degradation mechanisms of p-chloroaniline by persulfate at ambient temperature

Compound-specific isotope analysis (CSIA) is a useful technique that has received an increasing attention for studying the degradation mechanisms of organic contaminants based on stable isotope fractionation concepts. This study reports the degradation mechanisms of p-chloroaniline (PCA) at different pH values (3, 5, 7 and 9) induced by persulfate (PS) based on 13C isotope fractionation during its preferential oxidation with SO4− and OH. The results showed that the degradation of PCA followed first-order kinetics (rate constants, 0.026, 0.0362, 0.0754 and 0.0497 h−1 at pH = 3, 5, 7 and 9, respectively), with the fastest degradation under neutral conditions (pH 7). The degradation rate was found to be higher under alkaline conditions (pH 9) compared to acidic conditions (pH 3 and 5). A normal carbon isotope fractionation of PAC was observed under neutral and alkaline conditions (eg., εC = −0.8‰ ±0.10 at pH 7 and εC = −1.0‰ ±0.17 at pH 9). However, a reverse carbon isotope effect at pH 3 (εC = 0.6‰ ±0.07) and pH 5 (εC = 1.1‰ ±0.06) was observed, respectively. Based on the identified transformation products and the insights revealed by CSIA, the degradation pathways were proposed. The current findings are crucial in understanding the PCA degradation mechanisms with SO4− and OH in aqueous systems.

Activation of persulfate by MnOOH: Degradation of organic compounds by nonradical mechanism

Advanced oxidation processes (AOPs) based on persulfate (PS) has attracted great attention due to its high efficiency for degradation of organic pollutants. Manganese-based materials have been considered as the desirable catalysts for in-situ chemical oxidation since they are abundant in the earth’s crust and environment-friendly. In this study, manganese oxyhydroxide (MnOOH) was used as an activator for PS to degrade p-chloroaniline (PCA) from wastewater. The effects of MnOOH dosage, PS dosage and initial pH on PCA degradation performance were studied. Experimental results showed that PCA degradation efficiency was enhanced by higher MnOOH and PS addition, and the degradation efficiency was slightly inhibited as the initial pH increased from 3 to 9. MnOOH showed excellent stability and reusability when used as the activator of PS. In addition, a comprehensive study was conducted to determine the PS activation mechanism. The results revealed that PS activation by MnOOH followed a nonradical mechanism. No 1O2 was generated, and the main active substance in the reaction was the activated PS molecule on the surface of MnOOH. The hydroxyl group on the catalyst surface acted as a bridge connecting PS and the catalyst, leading to the activation of PS. The intermediates during PCA degradation were also analyzed, and three possible degradation pathways of PCA were proposed. This study expects to deepen the understanding of the PS activation mechanism by manganese oxide, and provides technical support for the practical application of AOPs of manganese-based materials for wastewater treatment.

Evaluating metabolic potential of Thauera sp. M9 for the transformation of 4-chloroaniline (4-CA)

Abstract Thauera sp. M9, was isolated after enrichment of microbial diversity in nitrogen free mineral salt medium (NFMSM) supplemented with 300 mg/l of 4-chloroaniline (4-CA). The isolate M9 was able to achieve complete degradation of 300 mg/l 4-CA supplement to NFMSM, after 30 h incubation. In addition to 4-CA, isolate M9 was able to achieve complete degradation of 300 mg/l 3-chloroaniline (3-CA), 21% degradation of 300 mg/l 2-chloroaniline (2-CA), and complete transformation of 50 mg/l of 3, 4-dichloroaniline (3, 4-DCA), was observed only in the presence of 0.02% (w/v) yeast extract (YE) supplement to NFMSM. The presence of catechol 2, 3-dioxygenase (C23O) activity in cell free extract and detection of 4-chlorocatechol (4-CC); 2-hydroxy muconic semialdehyde (2-HMS) in biologically transformed samples by mass spectroscopy (MS) analysis indicated to meta-cleavage of the aromatic ring. A plug flow reactor (PFR) was developed using polyurethane foam (PUF) and refractory brick pieces (RBP) as immobilization matrix. The treatment of simulated effluent supplemented with 300 mg/l 4-CA through PFR, resulted in 88% transformation of 4-CA and 70% lowering of chemical oxygen demand (COD). These observations suggest that Thauera sp. M9 could be a potential inoculum for developing bioremediation protocols for waste rich in chloroanilines (CAs).

Effect of Fe2O3 loading on CuO/CNT photocatalyst for degradation of p-Chloroaniline

Chloroaniline and its derivatives are generated from industrial chemical manufacturing processes including agricultural chemical, azo dyes and pigments, pesticides and herbicides. These compounds are found to be toxic and dangerous to aquatic and human life. Hence, their discharge into the environment must be regulated. Photocatalytic degradation is one of a promising method to remove such compounds due to its safety, low energy consumption and high efficiency. In this study, the research focused on the effect of iron oxides (Fe2O3) loading (5-50 wt%) on copper-carbon nanotubes (CuO/CNT) photocatalyst for degradation of p-chloroaniline (PCA) under visible light irradiation. The synthesized catalysts were characterized using Fourier Transform Infrared Spectroscopy to analyze its functional groups. Besides Fe2O3 loading, various parameters such as effect of PCA pH solution (3-11), catalyst dosage (0.125- 0.625 g L−1) as well as PCA initial concentration (10-100 mg L−1) were investigated. It was found that the highest degradation (75 %) of 10 mg L−1 PCA was achieved using 0.325 g L−1 10 wt% Fe2O3/50 wt% CuO/CNT at pH 7. Kinetics study showed that the PCA photodegradation followed pseudo first-order Langmuir-Hinshelwood model. It is believed that the Fe2O3/CuO/CNT can be a potential photocatalyst for degrading organics pollutant efficiently.

Toxicity assessment of p-choroaniline on Platymonas subcordiformis and its biodegradation.

The use of p-chloroaniline (PCA) in various aspects leads to its existence and accumulation in the environment. Relevant researches showed that PCA was a prime toxic pollutant that had imposed a serious risk to public health and the environment. This paper investigated the toxicity effects of PCA on Platymonas subcordiformis (P. subcordiformis) and the biodegradation of PCA by the marine microalga. In the toxicity experiments, the EC50 of PCA on P. subcordiformis at 24h, 48h, 72h and 96h was 41.42, 24.04, 17.15 and 13.05mgL-1, respectively. The pigment parameters including chlorophyll a, chlorophyll b, carotenoids, photosynthetic O2 release rate, respiration O2 consumption rate and the chlorophyll fluorescence parameters including Fv/Fm, ETR and qP decreased greatly while antioxidant enzyme activities (SOD, CAT) and the chlorophyll fluorescence parameter NPQ increased when P. subcordiformis exposed to PCA compared with the control group. Fv/Fm would be a suitable indicator for assessing the toxicity of PCA in marine environment based on the analysis of Pearson's correlation coefficient and Integrated Biomarker Response (IBR). The degradation assay in P. subcordiformis indicated that the green marine microalga had the ability to remove and degrade PCA, and the order of removal and degradation proportion of PCA was 2mgL-1 > 5mgL-1>10mgL-1. The maximum removal and biodegradation percentage was 54% and 34%, respectively.

Insights into the mechanism of non-radical activation of persulfate via activated carbon for the degradation of p-chloroaniline

Persistent organic pollutants (POPs) are widely distributed and have significant negative environmental impacts. Advanced oxidation processes (AOPs) based on sulfate radicals produced from persulfate (PS) have attracted considerable attention for the degradation of POPs, however, there are several disadvantages with these radical activation systems. This study examined the degradation of p-chloroaniline (PCA) by persulfate (PS) activated with activated carbon (AC). The effects of initial pH and dosage of AC were also investigated. Results showed that AC exhibits good catalytic activity toward PS. Increasing AC dosage significantly improved the PCA degradation rate but PCA removal was not obviously influenced by initial pH ranging from 3 to 9. PS activation in the PS/AC system was a non-radical process as demonstrated by (i) ethanol and tert-butyl alcohol having little effect on PCA removal and (ii) Electron Paramagnetic Resonance results showing no radicals signals in the PS/AC system. Results also demonstrated that TOC could be removed in PS oxidation and PCA dechlorination was rapid (in the initial 30 min). The three major intermediates identified during the PCA degradation in the non-radical oxidation process were N-(4-chloro-phenyl)-benzene-1,4-diamine, 4-chloro-phenyl-diazene and hydroquinone and two pathways of PCA degradation was proposed. This study proposes a new insights into the mechanism of PS activation by AC and an efficient method for POPs removal.

Anaerobic Degradation of Chloroanilines by Geobacter sp. KT5.

A chloroaniline-degrading bacterial strain isolated from polluted sediment in the Mekong River was identified as Geobacter sp. KT5. The obtained isolate was found to utilize a wide range of trichloroanilines (TCAs), dichloroanilines (DCAs), monochloroanilines (MACs), and aniline as sources of carbon and energy. It also used Fe(III) as a terminal electron acceptor under anaerobic conditions. Among the chlorinated anilines, KT5 utilized 2,3,4-trichloroaniline (234TCA) with the highest rate (2.48 ± 0.32µM day-1). On determining the degradation pathway for chloroanilines (CAs) in Geobacter sp. KT5, it showed that the removal of ortho and para halogen was dominant. Firstly, KT5 ortho-dechlorinated some TCAs to DCAs, and then reductively transformed them into MACs and aniline prior to complete degradation with the iron reduction stoichiometry and release of nitrogen and chlorine. The KT5 augmentation in sediment slurry enhanced the degradation of CAs and aniline; however, the anaerobic degradation rates in slurry were significantly lower compared to those in liquid media.

Investigation of p-chloroaniline formation in the reactions between different endodontic irrigants

The aim of this study was to determine whether p-chloroaniline (PCA) is formed in the reactions of sodium hypochlorite (NaOCl) with final rinse chlorhexidine (CHX), QMix (combination of ethylenediaminetetraacetic acid (EDTA), CHX and detergent) and EDTA/CHX solutions by thin-layer chromatography (TLC), proton nuclear magnetic resonance (1H NMR) and infrared (IR) spectroscopy. Commercially available 5.25% NaOCl solution was mixed with 2% CHX and QMix in 1:1 (v/v) ratio at room temperature. Furthermore, 2% CHX was associated with 17% EDTA under the same experimental conditions. The obtained solutions were evaluated qualitatively for color changing, precipitate and/or bubble formation and analyzed by TLC chromatography. The association products were investigated by spectroscopic (1H NMR and IR) methods in order to determine whether they contain PCA. It was found that interactions between NaOCl/CHX and CHX/EDTA led to forming of brown and white precipitate. When NaOCl was mixed with QMix, an orange-brown precipitate was formed. PCA was not detected as a product of the reactions between NaOCl and final rinse solutions of CHX, QMix and EDTA/CHX association.

Removal of p-chloroaniline from polluted waters using a cathodic electrochemical ceramic membrane reactor

Degradation of p-chloroaniline (PCA) was investigated using an electrochemical reactor with Ti/SnO2-Sb anode and cathodic electrochemical porous ceramic microfiltration (MF) membrane under galvanostatic control. Results showed that electrochemical degradation of PCA followed pseudo-first-order kinetics. At applied current 0.8 A and membrane flux 80 L m−2 h−1, complete degradation of PCA (initial concentration of 0.6 mM) was achieved after 90-min electrolysis following adding 0.2 mM Fe2+ at pH 3, with 75.1% of mineralization ratio and 46.7% of total nitrogen abatement. The production of OH via either anodic water oxidation or homogeneous and surface Fenton reaction was responsible for PCA degradation. The degradation pathways of PCA involving protonation, OH oxidation, and cathodic reduction were proposed by quantifying generated organic byproducts and inorganic nitrogen ions. Compared to cross-by operation, the cross-through operated EF system exhibited an enhanced oxidation power, leading to more efficient destruction of PCA and its toxic intermediate byproducts and improving electrical energy efficiency. This was ascribed to the increased ROS production and better contact of the contaminants with ROS present in the vicinity of membrane (cathode) surface induced by the enhanced mass transfer under membrane filtration. These results highlight the potential of the cross-through operated EF system to be used for the treatment of PCA-contaminated water and wastewater.

Activation of persulfate with metal–organic framework-derived nitrogen-doped porous Co@C nanoboxes for highly efficient p-Chloroaniline removal

Cobalt-based nanostructures have shown a great potential for radical production by activating persulfate (PS). Here, we report a facile strategy to synthesize nitrogen-doped porous Co@C nanoboxes (Co@NC) by pyrolysis of zeolitic imidazolate frameworks (ZIF-67), followed by partially etching away the metallic cobalt. With a nitrogen-enriched hollow porous carbon nanobox and embedded Co nanoparticles, the Co@NC shows high efficiency in PS activation for p-Chloroaniline (PCA) removal. The degradation study shows that a complete removal of high concentration PCA is done within two minutes, which is superior to most of the reported PCA removals with PS-based advanced oxidation processes (AOPs). More importantly, the Co@NC exhibits high catalytic activities in a wide range of pH from 5 to 9. The Co@NC also shows very limited Co2+ release with a dissolution proportion of 0.28%, much lower than previously reported Co-based catalysts, and remains high efficiency after five successive reaction cycles. A heterogeneous activation mechanism though surface reaction is proposed, in which PCA firstly absorbs on the carbon nanobox surface, then being oxidized by generated radicals and non-radical species. The unique structure and outstanding performance of Co@NC catalysts present new insights in catalyst design for PS-based advanced oxidation for organic pollutants removal in waste water.

Degradation of p-chloroaniline using an electrochemical ceramic microfiltration membrane with built-in electrodes

An electrochemical ceramic microfiltration membrane with built-in cathode (Ti mesh) and Ti/RuO2 anode, which had dual functions of separation and electrochemical oxidation, was developed for p-chloroaniline (PCA) removal from contaminated waters. Results showed that the degradation of PCA followed the pseudo-first-order kinetics in all conditions. PCA degradation efficiency increased with the increase of applied voltages in the range of 0–3.0 V. The optimum solution pH for PCA decay was 7.0. An initial PCA concentration higher than 30 μM had no significant influence (p > 0.05) on the degradation efficiency of PCA. At an applied voltage of 2.0 V and an electrolysis time/hydraulic retention time of 2 h, the removal efficiency of PCA under flow-through mode was found to be 3.6 times that of flow-by mode, due to the better contact and reaction of contaminants with the oxidants generated in the vicinity of membrane surface. It also showed that OH arisen from anodic water oxidation reaction played a key role in PCA degradation. Benzoquinone, aniline, p-aminophenol, hydroquinone, malonic acid, succinic acid, oxamic acid, maleic acid, oxalic acid, α-ketoglutaric acid and formic acid were identified as the main PCA decay products, leading to a lower biological toxicity of the effluent. The system also demonstrated a favorable performance for contaminant elimination after a long-term operation. These results highlight the potential of this electrochemical microfiltration membrane system for efficient PCA degradation.

FIA– Spectrophotometric methods for the determination of Naringenin in supplements and urine samples using diazotization coupling reactions

Direct FIA methods for estimation of Naringenin (NG) in different samples were proposed. These methods are based on diazotization coupling reactions of two reagents: method (A) p-chloroaniline (PCA) and method (B) procaine hydrochloride (PRH) with NG in basic medium. Yellow dyes with maximum absorption at 416 and 415 nm were formed respectively. Calibration curves were constructed over different NG concentrations, linearity was from 1- 70 and 1- 40 µgmL -1 with detection limits of 0.55 and 0.24 µgmL -1 for (A) and (B) respectively. All analytical variables involved in the FIA procedure were evaluated and optimized. The established methods were successfully applied for the determination of NG in its supplements and urine samples.

Physical and Chemical Methods Used for Determination of Structures of Some Imines Derived from Different Carbonyl Compounds

The project is concerned with the preparation of fifteen imines derived from 2-acetyl pyridine ,3 or 4 –hydroxy benzaldehyde and m-anisaldehyde with aromatic primary amines by standard method . These imines include namely ,hydroxylamine hydrochloride,o,m,p-amino phenols ,4-amino naphthol ,bromo or chloro aniline and p-anisidine . The main aims of the study is the determination of structures of these imines by the available physical method ,namely ,the melting points ,boiling points , U.V and IR spectra . Some chemical tests for functional groups are also included .This seems important from chemistry point of view as in the elucidation of tautomerism reactions happen in some oximes and phenolic oximes . Finally ,the influence of inter molecular hydrogen bonding on association (polymerization) of imines was also discussed

Directing the amount of CNTs in CuO–CNT catalysts for enhanced adsorption-oriented visible-light-responsive photodegradation of p-chloroaniline

Copper oxide (CuO, 10–90wt%) was loaded onto carbon nanotubes (CNTs) by electrosynthesis method. The catalysts (CuO/CNT) were characterized by XRD, nitrogen adsorption–desorption, ESR, FTIR, Raman, and XPS spectroscopy. The results indicated that a lower amount of CuO was dispersed well on the CNT, while higher loading was agglomerated, producing large-size crystallites, hence resulting in lower specific surface area. Adsorption studies revealed that the isotherms are fitted well with the Langmuir model. Moreover, the n value that was obtained from Freundlich model indicated that adsorption process is chemisorption. Photodegradation of p-chloroaniline (PCA) under visible light irradiation demonstrated that the 50wt% CuO/CNT catalyst gave the highest degradation (97%). It was concluded that CN moieties of PCA were chemisorbed on the catalyst prior to photodegradation, while the CuOC bonds, surface defects and oxygen vacancies were the main active site in enhancing the subsequent photodegradation. The kinetics of photodegradation were correlated with pseudo-first-order model, verifying the surface reaction was the controlling step. Remarkable mineralization results of PCA were attained by TOC (89.1%) and BOD5 (50.7%). It was also evidenced that the catalyst has a good potential toward degradation of various endocrine disruption compounds.

Mixtures of diflubenzuron and p-chloroaniline changes the activities of enzymes biomarkers on tilapia fish (Oreochromis niloticus) in the presence and absence of soil

The insecticide Diflubenzuron (DFB), used by many fish farming, when metabolized or degraded produces the extremely toxic compound p-chloroaniline (PCA). Once in the aquatic environment, these compounds can form mixtures and their bioavailability depends on factors such as the presence of soil. The toxic effects of the isolated compounds and their mixtures in the proportions: 75%, 50%, and 25% of PCA were analyzed in tilapia (Oreochromis niloticus) in the presence and absence of soil after 96h. The enzymes catalase (CAT), acid (AcP) and alkaline (AlP) phosphatases and alanine (ALT) and aspartate (AST) aminotransferases of the liver of the tilapia (Oreochromis niloticus) were used as biomarkers. DFB and the mixture containing 75% of this compound did not present high toxicity to fish; however, 25mg/L of PCA alone and 15mg/L of the mixture with 75% of this compound promoted 50% mortality of tilapia (Oreochromis niloticus). In the presence of soil, these toxicity values decreased to 37 and 25mg/L, respectively. Independent of the presence of soil, a synergistic effect was observed when the proportion of PCA was 75% and to the mixture, with 25% PCA was observed the antagonistic effect. Different concentrations of the compounds and their mixtures induced CAT activity independently of the presence of soil. Additionally, increases in phosphatases and transaminases activities were observed. In some cases, the enzymes also had their activities decreased and the dose-dependence effects were not observed. This research showed that the presence of soil influenced the toxicity of the compounds but not altered interaction type among them. Diflubenzuron, p-chloroaniline, and mixtures thereof caused disorders in enzymes important for the health of tilapia (Oreochromis niloticus).

Evaluation of degradation mechanism of chlorhexidine by means of Density Functional Theory calculations

Chlorhexidine (CHD), a germicidal drug, has degradation products that can be hemotoxic and carcinogenic. However, there is no consensus in literature about the degradation pathway. In order to shed light on that mechanism, we have employed Density Functional Theory to study reactants, in different protonation states, products and intermediates involved in the different pathways. Based on free energy values comparison and frontier molecular orbital analysis, we have obtained the most stable structures in each protonation state. CHD in saturated form has HOMO localized in one p-chloroaniline, and, due to molecule’s symmetry, HOMO-1 has contributions from the other side of the molecule, but mainly from the biguanide portion of the molecule, instead of from the p-chloroaniline. For the saturated form, we have studied two possible degradation pathways, starting from the monoprotonated structure, and three pathways starting from the neutral structure. We found out that the mechanisms proposed in literature, whose pathways lead to p-chloroaniline (PCA) formation in a smaller number of steps, are more likely than the mechanisms with more intermediate steps or pathways that do not predict PCA formation. Also, based on free energy results, we have found that the formation of another sub-product (PBG-AU) is favorable as well.

Mackinawite (FeS) activation of persulfate for the degradation of p-chloroaniline: Surface reaction mechanism and sulfur-mediated cycling of iron species

Among the numerous iron-based materials for persulfate (PS) activation, mackinawite (FeS) particles have gained considerable interest as a ubiquitous natural mineral due to their high reactivity. However, the iron and sulfur co-mediated reaction mechanism of PS activation by FeS remains ambiguous. In this study, FeS was applied as a catalyst to activate PS for p-chloroaniline (PCA) degradation and mineralization over a wide initial pH range (3.0–11.0). The reaction was found to follow pseudo-first-order kinetics, with rate constants ranging from 0.0044 to 0.0144min−1. The reaction mechanism was elucidated by electron spin resonance (ESR) and quenching studies. A heterogeneous activation mechanism, in which surface Fe(II) species activated PS to produce OHads and SO4−ads, controlled by surface reaction and diffusion was proposed, whereas OHfree and SO4−free diffusing from the FeS surface were mainly responsible for PCA degradation. The sulfur-mediated cycling of iron species was investigated by comparing PS activation by zero-valent iron (ZVI) and FeS, exogenous Fe(III) addition and X-ray photoelectron spectroscopy (XPS). The results suggested that Fe(II) and S(-II) experienced independent oxidations and that S(-II) species could regenerate Fe(II) from Fe(III) at the FeS surface. Therefore, the S(-II)-promoted Fe(II)/Fe(III) cycle resulted in less PS decomposition but a higher PCA mineralization efficiency. The findings of this study elucidated the novel surface activation mechanism of PS by FeS and provided useful information for utilizing FeS to remediate contaminated water.

Low transition temperature mixtures prompted one-pot synthesis of 5, 10 dihydropyrimido[4,5-b]quinoline-2,4(1H,3H)-dione derivatives

An efficient green protocol has been investigated for the synthesis of pyrimido[4,5-b]quinolines derivatives via one-pot three-component condensation of 4-chloro aniline, aromatic aldehyde and barbituric acid using low transition temperature mixtures as new generation and sustainable solvents. The process was accomplished with the use of greener and recyclable reaction media, simple methodology, easy workup procedures and no chromatographic purification with high yield. This new approach is expected to discover some significance in combinatorial synthesis of biologically active scaffolds.

Indium doped BiOI nanosheets: Preparation, characterization and photocatalytic degradation activity

Semiconductor photocatalysis is a promising method to remove the harmful compounds into harmless molecules. Herein, In-doped BiOI (In-BiOI) photocatalysts with highly exposed dominant {001} facets were synthesized through a facile hydrothermal method. The XRD, SEM and TEM determinations revealed the high crystallinity structure of the samples, and the XPS results confirmed the doping of In. The In-BiOI nanosheets exhibited a higher activity in the photodegradation of p-chloroaniline (PCA) than that of pristine BiOI, among which the In-2 BiOI sample (feed mole ratio of In:Bi=2%) possessed the best performance. Doping with In didn’t alter the structure, morphology, specific surface area or light absorption capacity of BiOI, but significantly improved its charge separation efficiency and transport capability, which were verified by the results of the lower PL emission, larger photocurrent intensity and smaller arc radius of EIS plots. More importantly, the mechanism of photocatalytic degradation is studied systematically, revealing that O2− and h+ were the major reactive species during the photodegradation process. Finally, the possible role of In-doping in enhancing the photocatalytic performance of BiOI is proposed.