ADSORPTION CHARACTERISTICS OF CHLOROPHENOLS FROM AQUATIC SYSTEMS BY HYPERCROSSLINKED RESINS MODIFIED WITH BENZOYL GROUP

A hypercrosslinked polymeric adsorbent （ZH-03） for adsorbing and removing chlorophenolic compounds from their aqueous solutions was studied, including the static adsorption. The equilibrium adsorption data were fit to Freundlich adsorption isothermic models to evaluate the model parameters. Thermodynamic studies on the adsorption of chlorophenolic compounds on ZH-03 indicated that there were chemisorption transitions for 2,4,6-trichlorophenol and physical adsorption processes for 2-chlorophenol and 2,6-chlorophenol, and ZH-03 showed the homogeneous nature of the adsorbent surface. Column adsorption for chlorophenols wastewater shows the advantages of the ZH-03 adsorbent for adsorbing the following chlorophenolic compounds as 2-chlorophenol, 2,6-dichlorophenol and 2,4,6-trichlorophenol. Sodium hydroxide was used for desorpting chlorophenols from ZH-03 and showed excellent performance.

分散液液微萃取-反相液液微萃取-扫集-胶束电动色谱法测定红酒中的3种氯酚类物质

建立了分散液液微萃取（DLLME）-反相液液微萃取（RP-LLME）-扫集-胶束电动色谱富集模型，并用于红酒中五氯酚（PCP）、2，4，6-三氯酚（TCP）和2，4-二氯酚（DCP）3种氯酚的测定。实验考察了两步微萃取的萃取参数对氯酚萃取率的影响和样品分离富集的电泳条件。最佳萃取条件 DLLME 为：3.5 mL 红酒（ pH 3.0，120 g / L NaCl），300μL 正己烷（萃取剂）；RP-LLME 为：25μL 0.16 mol / L NaOH（萃取剂）。最佳电泳条件：25 mmol / L NaH2 PO4，100 mmol / L 十二烷基硫酸钠（ SDS），30％（ v / v）乙腈，pH 2.3；分离电压-15 kV；样品基质为80 mmol / L NaH2 PO4；压力进样20 s×20.67 kPa（3 psi）。PCP 和 TCP 的线性范围为0.5～100μg / L（ r≥0.9910）， DCP 的线性范围为1.5～80μg / L（r =0.9851）。3种分析物的检出限（ S / N =3）为0.035～0.114μg / L，加标回收率为75.2％～104.7％，相对标准偏差≤6.17％。该方法富集倍数高、灵敏度高、重现性好、分析速度快，可为不同样品基质中痕量氯酚污染物及某些弱酸性有机污染物测定提供参考。

Studies on the Quantitative Structure-activity Relationship of Toxicity of Chlorophenol Serial Compounds in the ab initio Methods and Substitutive Position of Chlorine Atom (N_(PCS))

20 Quantum chemical parameters of chlorophenol compounds were fully optimized by using B3LYP method on both 6-31G^＊ and 6-311G^＊ basis sets. These structural parameters are taken as theoretical descriptors, and the experimental data of 20 compounds＇ aquatic photogen toxicity（-lgEC50） are used to perform stepwise regression in order to obtain two predicted -lgEC50 correlation models whose correlation coefficients R^2 are respectively 0.9186 and 0.9567. In addition, parameters of chlorine atom＇s substitutive positions and their correlations （NPCs） are taken as descriptors to obtain another predicted -lgEC50 model with the correlation coefficient R2 of 0.9444. Correlation degree of each independent variable in the three models is verified by using variance inflation factors （VIF） and t value. In the cross-validation method, cross-validation coefficients q^2 of 3 models are respectively 0.8748, 0.9119 and 0.8993, which indicates that the relativity and prediction ability of this model are superior to those of the model obtained by topological and BLYP methods.

Immobilization of microorganisms using carrageenan gels coated with chitosan and application to biodegradation of 4-chlorophenol

A new cell immobilization method based on the replacement of KCl by KCl+chitosan as the gelling agent was developed. The experimental results showed that through addition of chitosan into gelling agent, the mechanical strength and the thermal stability of the carrageenan gel were greatly improved. The new immobilization method was used to entrap a chlorophenol degrading microorganism. The immobilized microbial cells were applied for chlorophenol biodegradation. The experiments demonstrated that immobilized cells exhibit a higher bioactivity in the degradation of chlorophenol than free cells.

Electrochemical Removal of Chlorophenol Pollutants by Reactive Electrode Membranes: Scale-Up Strategy for Engineered Applications

Chlorophenols(CPs)are significant refractory pollutants that are highly toxic to humans and other organ-isms.Reactive electrode membranes(REMs)show considerable potential in the electrochemical removal of refractory pollutants by allowing flow-through operations with convection-enhanced mass transfer.However,relevant studies are commonly performed on the laboratory scale,and there is no straightfor-ward method that guarantees success in scaling up engineered REM reactors.In this study,we demon-strated that a tubular concentric electrode(TCE)configuration with a titanium suboxide ceramic anode and a stainless-steel cathode is suitable for large-scale CPs removal.Both theoretical and experi-mental results showed that the TCE configuration not only allows the electrode surface to be orthogonal to electric field lines everywhere,but also has an ohmic resistance that is inversely proportional to the length of the electrode.In addition,the TCE configuration can be operated in either the anode-to-cathode(AC)or the cathode-to-anode(CA)mode based on the flow direction,creating adjustable condi-tions for selective degradation of CPs.This was confirmed by 98%removal of 2,4-dichlorophenol(2,4-DCP)and 72.5%removal of chemical oxygen demand(COD)in the CA mode,in which the kinetic constant was one order of magnitude higher than that for the AC mode under flow-through single-pass operations.This can be explained by the lower activation energy and free energy in the CA mode,as revealed by the-oretical calculations and experimental measurements.The TCE configuration is also suitable for a numbering-up strategy to scale up the electrochemical reactor without increasing the ohmic resistance or decreasing the specific electrode area,achieving 99.4%removal of 2,4-DCP with an energy consump-tion of 1.5 kW·h·m^(-3) when three TCE modules were employed.This study presents a suitable electrode design configuration for the REM reactor,offering effective strategies to bridge the“Valley of Death”encountered when scaling up the electrochemical removal of CP pollutants.

An Optical Fiber Sensor Probe Using a PMMA/CPR Coated Bent Optical Fiber as a Transducer for Monitoring Trace Ammonia

Ammonia sensors have broad spectrum of applications for industrial process control as well as for environ-mental monitoring. An optical fiber ammonia sensor probe has been developed by using a bent optical fiber having dual poly(methyl methacrylate) (PMMA)/chlorophenol red (CPR) coatings as a transducer. This sen-sor probe was tested for monitoring trace ammonia in gas samples using air as sample matrix. The reaction of ammonia with CPR causes a color change of the reagent, which was detected by using fiber optic evanes-cent wave absorption spectrometry as a sensing signal. By adopting a dual layer coating structure, the sensor probe has faster response compared to a sensor using a broadly accepted sensing reagent-immobilized poly-mer coating structure. The sensor developed in this work is sensitive, has a detection limit of 2.7 ppb NH3 in air, which is the most sensitive among the reported optical fiber ammonia sensors to the best knowledge of the authors. The sensor is also reversible and has a response time of 25 minutes. The features of high sensi-tivity, reversibility and reasonable response time make this sensor technique very attractive for air quality monitoring.

Reversed flow injection spectrophotometric determination of low residuals of chlorine dioxide in water using chlorophenol red

A novel, simple, rapid, sensitive and highly selective flow injection procedure for the spectrophotometric determination of chlorine dioxide in the presence of other chlorine species, viz,free chlorine, chlorite, chlorate and hypochlorite, is developed. The method is based on the discoloration reaction between chlorine dioxide and chlorophenol red and can overcome the shortcomings existed in direct spectrophotometric determination for chlorine dioxide owing to the serious interference of free and combined chlorine. The procedure gave a linear calibration graph over the range 0—0.71 mg/L of chlorine dioxide. With a detection limit of 0.024 mg/L and a sample throughput of 60 samples/h.

QSBR Study on the Anaerobic Biodegradation of Chlorophenols

18 Physicochemical and quantum chemical parameters of 12 kinds of chlorophenols are calculated in this paper. QSBR （quantitative structure-biodegradability relationship） study is performed using simca statistical software by PLS regression analysis method on anaerobic biodegradation data （logKb）, and the QSBR model is developed with favorable prediction. The model shows that the size and energy of the molecule are the dominant factors affecting the anaerobic biodegradation of chlorophenols. And the degradation rate constants （logKb） increase with the increase of core-core repulsion （CCR）, average molecular polarizability （α）, total surface area （TSA）, heat of formation （HOF） and total energy （TE）. while decrease with the increase of molecular connectivity index （^1X^V）, relative molecular mass （Mw） and electronic energy （EE）.

Efficient oxidative degradation of 2-chlorophenol and 4-chlorophenol over supported CuO-based catalysts

A series of metal oxide catalysts for catalytic oxidative degradation of 2-chlorophenol （2-CP） and 4-chlorophenol （4-CP） were prepared, and the supported CuO catalysts were studied particularly. The supported CuO catalysts were characterized by XRD and NH3-TPD techniques, in which CuO/γ-Al2O3 exhibited high degradation activity. The addition of Na2O or K2O into CuO/γ-Al2O3 improved the oxidative degradation of CPs remarkably, in which Na2O was more efficient than K2O. Over CuO/γ-Al2O3-Na2O, CPs were completely converted and the liberation of the inorganic chloride from 2-CP or 4-CP reached 97% or 100% respectively at 30 ？C for 2 h. The supported CuO catalysts with good dispersion of CuO particles and less acid sites were favorable for the efficient oxidative degradation of CPs. In addition, the initial pH of the reaction solution was found to be an important factor which influenced the catalytic oxidative degradation of CPs and the initial pH of 11.2 and 9.8 was preferred for the oxidative degradation of 2-CP and 4-CP respectively over CuO/γ-Al2O3 catalyst.

Phytotoxic Effects of 4-Chlorophenol and 2,4-Dichlorophenol in the Germination of Seeds of <i>Phaseolus vulgaris</i>and <i>Zea mayz</i>

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.

Development of Simultaneous HPLC-Fluorescence Assay of Phenol and Chlorophenols in Tap Water after Pre-Column Derivatization with 3-Chlorocarbonyl-6,7-dimethoxy-1- methyl-2(1H)-quinoxalinone

Chlorophenols (2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol and 2,4, 6-trichlorophenol) may be presented in natural waters or drinking water as a result of disinfection processes involving chlorination, or as contaminants derived from domestic products, industrial operations and agricultural chemicals. A previous HPLC-UV method for determination of phenol and five chlorophenols in tap water using 4-fluoro-7-nitro-2,1,3-benzoxadiaole as a UV labeling reagent shows limited sensitivity. Here, we present an improved HPLC-fluorescence detection method for simultaneous determination of phenol and the above chlorophenols in tap water after pre-column derivatization with 3-chlorocarbonyl-6,7-dimethoxy-1-methyl-2(1H)-quino- xalinone (DMEQ-COCl), using a short, narrow column (50 × 2.1 mm i.d., packed with 5 μm particles of C18 material) to improve the sensitivity. Standard samples containing the compounds are derivatized with DMEQ-COCl in borate buffer (pH 9.0) at room temperature for 3 mins. The response is linear in the concentration range of 0.01 - 0.05 to 0.5 mg/L with r2 values ≥0.9967 for all compounds. The lower limits of detection are 0.001 to 0.008 mg/L, and the coefficients of variation are less than 8.8%. The recovery values from tap water spiked with standard samples are satisfactory. The present method is suitable for examining whether or not tap water samples are contaminated with phenol and chlorophenols in excess of regulatory values.

Phenoxyacid Herbicides in Stormwater Retention Ponds: Urban Inputs

Surface water runoff from urban centers is a major source of environmental pollution which impacts water quality in downstream aquatic habitats. Phenoxyacid herbicides are some of the most widely globally used herbicides in agriculture and urban environments for weed control. Their transformation products which in- clude chlorophenols can be more toxic than the active ingredients. We used LC/MS/MS to analyzed simul- taneously these acid herbicides and their transformation products in stormwater retention ponds taken from an urban environment to examine the occurrence and potential release of these herbicides from urban inputs into downstream waters. 2,4-dichlorophenoxyacetic acid and mecoprop were detected in all samples col- lected from the ponds and at the highest concentrations, while 2-methyl-4-chlorophenoxyacetic acid was de- tected only in spring and summer. Two transformation products, 4-chloro-2-methylphenol and 2,4-di- chlorophenol were detected in samples primarily at inlet locations on the ponds indicating that degradation had occurred in surface soils prior to surface water runoff.

Flow Injection Amperometric Determination of Phenol and Chlorophenols at Single Wall Carbon Nanotube Modified Glassy Carbon Electrode

Single wall carbon nanotube modified glassy carbon electrode (SWCNT/GCE) was used for flow-injection analysis (FIA) for phenolic compounds (phenol (P), 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorphenol (TCP) and pentachlorophenol (PCP)). Experimental variables such as the detection potential, flow rate and pH of the carrier solution, 0.1 M sodium acetate, were optimized. Under these conditions, the designed electrode showed a very good performance for the amperometric measurements, with no need to apply a cleaning or pre-treatment procedure. The operational stability was tested with 20 repetitive injections of each analyte and was found to be good. The analytical performance of the SWCNT/GCE electrode under flow through conditions was tested and was found to be impressive. When it is compared with other enzymatic and non-enzymatic sensors, it shows wider dynamic range for the detection of phenolic compounds with low limits of detection. These results suggest that the method is quite useful for monitoring and analyzing phenols and chlorophenols.

Extraction and Determination of Three Chlorophenols by Hollow Fiber Liquid Phase Microextraction - Spectrophotometric Analysis, and Evaluation Procedures Using Mean Centering of Ratio Spectra Method

A method termed hollow fiber liquid phase microextraction (HF-LPME) was utilized to extract three chlo- rophenols, 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6- trichlorophenol (2,4,6-TCP), separately from water. The extracted chlorophenols were then separated, identified, and quantified by UV-Vis spectrophotometry with photodiode array detection (UV-Vis/DAD). In the study, experimental con-ditions such as organic phase identity, acceptor phase volume, sample agitation, extraction time, acceptor phase NaOH concentration, donor phase HCl concentration, salt addition, and UV absorption wavelength were optimized. The statistical parameters of the proposed method were investigated under the selected con-ditions. The analytical characteristics of the method such as detection limit, accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) was calculated. The results showed that the proposed method is simple, rapid, accurate and precise for the analysis of ternary mixtures.

Simple HPLC–UV Analysis of Phenol and Its Related Compounds in Tap Water after Pre-Column Derivatization with 4-Nitrobenzoyl Chloride

The purpose of this study is to develop an HPLC-UV (280 nm) method for simultaneous determination of phenol, five chlorophenols (2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, and 2,4,6-trichlorophenol), and three phenylphenols (2-phenylphenol, 3-phenylphenol, and 4-phenylphenol) in tap water after pre-column derivatization with 4-nitrobenzoyl chloride. Standard curves were obtained after derivatization with 4-nitrobenzoyl chloride in borate buffer (pH 8.5) at 50°C for 1 min. The nine 4-nitrobenzoyl derivatives were well separated in less than 15 min on a Cholester column. Calibration plots were linear in the range of 0.02 ~ 0.12 to 0.9 mg/L, with r2 values ≥0.9928, for all compounds. The lower limits of detection were 0.006 to 0.05 mg/L. The coefficients of variation were less than 12.0%. The recovery values from tap water spiked with a standard mixture of test compounds were satisfactory. While the levels of phenol, five chlorophenols, and three phenylphenols in tap water were below the lower limit of determination, our method is expected to be useful for monitoring and/or identifying environmental water samples that are contaminated with these compounds, i.e., for assessing compliance with the official guidelines of the World Health Organization.

Dechlorination of chlorophenols by zero valent iron impregnated silica

Laboratory studies were conducted to find out the efficacy of uniquely prepared zero valent iron impregnated silica in transforming xenobiotic chlorophenols namely 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. Continuous mode column experiments were performed to investigate the transformation of chlorophenols by varying pH, column height, flow rate and initial chlorophenol concentration. Reusability study of the zero valent iron impregnated silica was studied as well as the morphological changes and the chemical composition of the catalyst medium were also investigated. Dechlorination kinetic studies were conducted and the order of dechlorination of chlorophenols was found to be 2,4,6-trichlorophenol 〉 2,4-dichlorophenol 〉 4-chlorophenol. The optimum pH, column height and flow rate were found to be 7, 20 cm and 0.75 L/hr respectively for all chlorophenols in the reaction duration of 4 hr. Intermediates formed during dechlorination study were identified by gas chromatography-mass spectroscopy analysis. This method was applied to real pulp and paper wastewater and was found satisfactory.

Probabilistic ecological risk assessment for three chlorophenols in surface waters of China

Individual and combined assessment of risks of adverse effects to aquatic ecosystems of three chlorophenols（CPs）,including 2,4dichlorophenol（2,4-DCP）,2,4,6-trichlorophenol（2,4,6-TCP） and pentachlorophenol（PCP）,were conducted.A probabilistic approach based on the concentrations of CPs in surface waters of China was used to determine the likelihood of adverse effects.The potential risk of CPs in surface waters of China was determined to be of concern,especially PCP and mixtures of CPs.The risks of adverse effects were examined as the joint probabilities of exposure and response.The joint probability for PCP was 0.271 in the worst case and 0.111 in the median case,respectively.Based on the cumulative probability,5% of aquatic organisms included in the assessment would be affected 21.36% of the time in the worst case and 5.99% of the time in median case,respectively.For the mixtures of CPs,the joint probability were 0.171 in the worst case and 0.503 in median case,respectively and 5% of species would be affected 49.83% of the time for the worst case and 12.72% in the median case,respectively.Risks of effects of the individual CPs,2,4-DCP and 2,4,6-TCP were deemed to be acceptable with a overlapping probability of 0.1 with 5% of species being affected less than 4% of the time.

Mineralization of 4-Chlorophenol under Visible Light Irradiation in the Presence of Aluminum and Zinc Phthalocyaninesulfonates

Photosensitized oxidation of 4 chlorophenol (4CP) by the title complexes (AlPcS and ZnPcS) in aerated aqueous solution upon visible light irradiation ( λ ≥450 nm) has been investigated using methanol as a disassociating reagent. It is confirmed that the monomeric species of the sensitizer is more active than the corresponding dimer in singlet oxygen generation for 4CP oxidation. However, the monomer is also the main component found in the sensitizer's photobleaching. In this regard, AlPcS is much more stable than ZnPcS, and the photobleaching is observed to proceed via singlet and triplet oxygen, respectively. The final products of 4CP oxidation in alkaline solution are carbon dioxide and chloride ions, while at pH=7 and pH=3 the p benzoquinone is the product. The temperature is found to have influence on both the photosensitized degradation of methyl orange and ZnPcS photobleaching, with an activation energy of 15 8 and 24 2 kJ/mol, respectively.

Sorption of chlorophenols onto fruit cuticles and potato periderm

To better understand the interaction mechanisms of plant surfaces with polar organic compounds, sorption of 4-chlorophenol, 2,4- dichlorophenol, and 2,4,6-trichlorophenol by fruit cuticles （i.e., tomato, apple, and pepper）, and potato tuber periderm were investigated. The roles of cuticular components （waxes, cutin, cutan and sugar） on sorption of chlorophenols are quantitatively compared. Cutin and waxes govern the sorption capacity of bulk apple cuticle by hydrophobic interactions. Potato periderm with highest sugar content exhibits the lowest sorption capability for the chlorophenols. With the increase of hydrophobicity （i.e., Kow ） of sorbate, the relative contribution of lipophilic components （wax, cutin and cutan） on total sorption increases, however, the ratios of Koc to Kow decreases due to increasing ionization degree of sorbates.

Newly developed Fe3O4–Cr2O3 magnetic nanocomposite for photocatalytic decomposition of 4-chlorophenol in water

Chlorophenols, typically 4-chlorophenols are highly toxic and non-biodegradable organic contaminants which pose serious threat to the environment, particularly when released into aqueous medium. The removal of these pollutants by efficient method has received worldwide concern in recent past. A new Fe3O4–Cr2O3 magnetic nanocomposite was synthesized by wet chemical method under ultrasonic irradiation. Microstructure and morphology of the nanocomposite were characterized by powder X-ray diffraction（XRD）,Fourier transform infrared（FT-IR）, and a transmission electron microscope（TEM）. Magnetic and optical properties were studied by a vibrating sample magnetometer（VSM） and an ultraviolet–visible（UV–Vis） spectrophotometer respectively. The magnetic nanocomposite（MNC） was used as photocatalyst for effective decomposition of 4-chlorophenol in water under ultraviolet（UV） irradiation.