Chloroorganic Compounds Research Articles

Vacuum - UV - oxidation of chloroorganic compounds in an excimer flow through photoreactor

The application of a novel vacuum-UV excimer flow through photoreactor (Λ = 172 nm) to the degradation of chloroorganic compounds in water is presented. A sample of ground water, contaminated with trichloroethene (Tri), 1,2-dichloroethene (1,2-DCE) and tetrachloroethene (Per), was purified successfully without the addition of oxidizing agents like H 2 O 2 or O 3. During the VUV-oxidation the intermediary formation of 1,1,2-trichloroethane (1,1,2-Tri) was established by GC-MS analysis. Over 93% of the organically bound chlorine atoms were transformed to inorganic chlorine ions ( Cl −). The photomineralization of 2,4-dichlorophenol (2,4-DCP) is presented on the basis of 2,4-DCP, Cl − and TOC analyses. In few of technical applications the volume-corrected energy efficiencies | −s of the degradation of 2,4-DCP were determined for different intensities of irradiation and different flow rates (e.g. | −s(142 W, 481/min) = 16200 mg/kWh).

The development of a new water quality classification system for Finland

The water quality classification system in Finland consists of three different sub-systems: a quality-based classification of watercourses for recreational purposes, a raw water (for domestic use) classification and a quality classification of watercourses for fishing. As a combination of these three sub-systems a general water quality classification has been widely used since 1988. However, there is a need to improve this system to be more sensitive in classification e.g. in the occurrence of harmful substances, especially organic chlorocompounds originating from pulp bleaching, and the early stages of eutrophication in very oligotrophic lakes. Also the quality classification of small rivers, very typical for Finland, needs more data about the biocoenosis, the living part of the river. Some ideas to improve the classification system in these respects are presented.

Anaerobic treatment of kraft bleaching plant effluent

Anaerobic treatment of a kraft bleaching plant effluent was studied with focus on the removal of chlorinated organic compounds and biochemical O2 demand (BOD). Experiments were carried out using a laboratory-scale anaerobic fixed-film process operated at different hydraulic retention times (HRTs). The process efficiently removed a variety of chloro-organic compounds when the HRT was 10 h or longer. However, a very long treatment time was required for significant removal of chlorofor; in fact, at the shortest HRT tested (6 h), there was a net production of chloroform. The overall removal of organically bound chlorine, measured as adsorbable organic halogens, was about 50%, and 60% removal of the extractable organic chlorine was achieved at an HRT of 15 h. About 70% of the BOD7 and 20% of the chemical O2 demand (COD) were removed. Up to 0.19 Nl of methane was produced per gram of COD removed by the treatment. When th HRT of the anaerobic process was shortened from 10 to 6 h, the methane production ceased.

The oxidative degradation of carbon and its role in the de-novo-synthesis of organohalogen compounds in fly ash

The behaviour of organic carbon, organic chlorine, and the volatile organic chlorine in fly ash was studied during thermal treatment at 275°, 300°, 350° C. Additionally the formation of PCDD/PCDF, PCIBz and PCIPh was investigated. It is shown that the degradation of carbon can be described by a combination of two first order reactions. These reactions and the change of the organic chlorine are correlated with the de-novo-synthesis of organic chlorocompounds. The yields of the reaction giving PCDD/PCDF PCBz and PCIPh were determined. In addition differential scanning calorimetry is used to describe the change of reactivity of the fly ash during the thermal treatment.

Fate of Organochlorine Compounds During Aquifer Storage and Recovery: The Las Vegas Experience

AbstractTwo water quality concerns with aquifer storage and recovery (ASR) operations are (1) the fate of organochlorine compounds, such as trihalomethanes (THMs), in the treated recharge source, and (2) the formation of organochlorine compounds from precursor materials following the chlorination of recovered water. The fate of chloroorganic compounds in chlorinated Colorado River water was studied during a 1989 recharge/recovery operation conducted by the Las Vegas Valley Water District (LVVWD). Water samples were obtained from two dual‐purpose wells during the pumping cycle for THMs and other indicators of organochlorine precursors. The percentage recovery of THMs was approximately the same as the percentage recovery of Colorado River water. This suggests that the removal of organochlorine compounds (e.g., by sorption) did not appreciably occur in the aquifer materials at the two well sites. Recovery of source water was incomplete. Accordingly, dissolved organic carbon (DOC), representing precursor material, remained in the aquifer at the end of the pumping cycle. The Las Vegas experience suggests that prolonged recharge and storage of Colorado River water in similar hydrogeologic basins (e.g., the Tucson basin) could result in problems with THM compliance at the well head. This will be a problem if THM standards are reduced during the interval that water is stored.

Supercritical fluid extraction of polychlorinated dibenzodioxins and dibenzofurans from soil samples

The extraction with supercritical CO 2 is compared with the well known soxhlet method in order to reduce the required time for the extraction of soil samples. In the first step of this study extractions were carried out using sand spiked with three chloroorganic compounds. In order to explore the influence of three variables on the recovery of these compounds the statistical method of factorial design was applied. Using the results of this investigation the optimum extraction conditions from soil samples were determined by means of the sequential simplex method. In these experiments the extractable organic halogen (EOX) was used as a rough estimation parameter. Finally the extraction of two soil samples was conducted in order to determine the concentration of polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF). The results of the trials with supercritical CO 2 were compared with the extraction data of the soxhlet method and they correspond well.

Treatment of Bleaching Effluents in Aerobic/Anaerobic Fluidized Biofilm Systems

Biodegradation of chloroorganic compounds in real industrial bleaching effluents (chlorination and extraction), with adapted biofilm in fluidized sand bed reactors, was studied under aerobic and anaerobic conditions. The effluents were only diluted and supplied with mineral nutrients. Two reactor combinations were compared with a single stage aerobic digestor (AFB). In the anaerobic-aerobic reactors in series (AAS), the effluents were first treated anaerobically followed by an aerobic reactor in a single pass. In the anaerobic-aerobic recycle reactor (AAR), the reactor content was periodically moving back from aerobic to anaerobic fluidized beds. The reactors were running continuously for one year. The most significant differences observed were between aerobic and anaerobic single reactors. Generally anaerobiosis reduced performance in terms of global parameters (COD, NPOC, AOX). With a residence time of 18 h for each reactor, COD and AOX typically decreased by 15-32 % for each aerobic reactor system (AFB, AAS, AAR), whereas a decrease of typically 4-15 % was observed in the purely anaerobic system. From GC and GC/MS analysis it was evident that in the anaerobic reactors, 2,4,6-trichlorophenol was first converted to 2,4-dichlorophenol. In all three systems 2,4,6-trichlorophenol and dichlorophenols were almost completely removed.

Degradation of chlorinated lignin compounds in a bleach plant effluent by the white-rot fungus Trametes versicolor

Chlorinated lignin derivatives in a combined bleach plant effluent from sulphite pulping were degraded by several white-rot fungi among which Trametes versicolor (Coriolus versicolor) strains were the most efficient. With glucose as co-substrate, about 90% colour reduction was achieved within 3 days. Simultaneously, the concentration of chloro-organic compounds measured as adsorbable organic halogens decreased by about 45%. As shown by gel chromatography, the high-molecular-weight fraction in the effluent was completely depolymerized while over 50% of total aromatic compounds were degraded. The presence of a co-substrate was necessary for all these activities of the fungus. The residue obtained after degradation was extremely recalcitrant and not further degradable.

Fractionation of chloroorganic compounds on a carbon cartridge

Solid phase extraction on a carbon cartridge for fractionation of some chlorinated compounds (non-planar and planar polychlorinated biphenyls, polychlorinated naphthalenes, hexachlorobenzene and DDE) is demonstrated. The method is simple and requires small volumes of solvents in comparison to other separation techniques on carbon columns.

Study on the electrostatic interaction in organic chlorocompounds. Enthalpies of combustion and formation of 1,3- and 1,4-dichlorobutanes

The enthalpies of combustion and vaporization of 1,3- and 1,4-dichlorobutanes have been measured in a tantalum-lined rotation bomb calorimeter and an LKB vaporization calorimeter and from these values the gaseous enthalpies of formation of the compounds are calculated as 194.98 ±1.78 and 183.40±1.94 kJ mol −1, respectively. The electrostatic interactions in these molecules are discussed.

Impact of bleached kraft mill effluents on drinking water quality

Bleaching effluents from kraft pulp mills contain large quantities of chlorinated organic compounds, some of which are mutagenic. Mutagenic chloro-organic compounds are also formed as by-products in chlorination of drinking water. The work reported here was a combined field and laboratory study aimed at comparing the evidence of health risks from pulp mill contaminants in drinking water, with corresponding evidence from normal, chlorine disinfection by-products. The study was performed in a Swedish river basin with a large, public water works located downstream from a bleached kraft mill. Chemical analyses (gas chromatography and determination of adsorbable organic halogen) and bioassays for mutagenic activity (bacterial and mammalian cell bioassays) were performed on samples of river water, drinking water and laboratory produced drinking water. The study showed that the bleached kraft effluents caused a considerable, long-range transport of chloro-organic substances in the receiving waters, and a substantial increase in the total amount of organic chlorine in drinking water produced downstream from the mill. As regards Ames mutagenic compounds, however, chlorination of naturally occurring humic substances during the chlorine disinfection step in drinking water production, proved to be a far more important source. The contribution of volatile chloro-organic compounds from the kraft mill was also much smaller than the contribution from normal disinfection by-products. The chromosome aberration tests gave no clear evidence of a positive response for any of the samples tested.

Removal of Chlorophenols and Chlorolignins from Bleaching Effluent by Combined Chemical and Biological Treatment

Organic matter from spent bleaching effluents (from chlorination (C) or extraction (E) stages, or a mixture of both) was effectively precipitated as a water insoluble complex with polyethyleneimine (polyimine). Precipitation was performed in a pilot unit operating automatically. The colour, chemical oxygen demand (COD), and adsorbable organic halogens (AOX) were reduced in the C-effluent by up to 92%, 65%, and 84%, respectively. Regarding the E-stage effluent, reduction was up to 76% for colour, 70% for COD, and 73% for AOX. No significant reduction of BOD5 was observed in the supernatant of the treated effluent. Fish toxicity was greatly reduced. Laccase increased the molecular weight of the effluent constituents, thus facilitating subsequent precipitation. After treatment with laccase, the bulk of mono- and dichlorophenol is coprecipitated with the liquors from the C and E bleaching stages. Fungi (representatives of the genera Aspergillus and Penicillium) achieved an appreciable level of degradation of chlorophenols and other chloroorganic compounds from the bleaching effluent.

A simple, selective and sensitive liquid-chromatographic or flow-injection detector for chloro-organic compounds based on ion-selective electrodes

The application of a chloride-selective electrode in flow injection analysis of chloro-organic compounds is described. In this feasibility study, the organic compound is destroyed, liberating chloride ions, either electrochemically or by UV radiation before entering the electrochemical cell. The detection limit of an assay performing about 30 determinations per minute lies in the nanomole range. The standard deviation lies at about 5% if 50 μl of a 10−3 mol/l solution of a Cl-containing compound are injected. Compounds containing bromo-, iodo- or thiol groups are also detected. With additional ISE's they can be determined more selectively.

Triplet exciplexes — have they been detected in the liquid phase?

The quenching of triplet porphyrins, chlorophyll-a and anthracene by nitro compounds, quinones and organic chloro compounds and triplet phenazine by N,N-dimethylaniline in non-polar solvents has been reinvestigated using conventional and laser flash photolysis techniques. Contrary to earlier reports, neither kinetic nor spectral evidence has been found to corroborate the formation of triplet exciplexes in these systems.

Radiolytic dechlorination of polychlorinated biphenyls

In the late 1960s, Sherman (J. Phys. Chem., 1968, 72 , 2287) found that in alkaline isopropanol solutions some chloro-organic compounds were radiolytically dechlorinated, via a chain reaction. In the 1970s, this work was extended to the polychlorinated biphenyls (PCBs) by Shinozaki and co-workers (Bull. Chem. Soc. Jpn., 1974 47 , 1889). We have successfully repeated and extended the work reported by Shinozaki and co-workers. We found a higher efficiency (G value) for dechlorination. The effects of various inorganic and organic additives on the dechlorination process were also determined. The radiolytic dechlorination process has been used successfully with drained capacitors containing adsorbed PCBs, as well as with soil contaminated with PCBs. Successful runs were done with 20-L solutions. A mobile industrial plant, with a capacity to dechlorinate about 25 000 kg of PCBs per year, is being designed. The results of the experiments and some aspects of the design of the mobile plant are presented.

Photochemistry of Colloidal Metal Sulfides. 5. Fluorescence and Chemical Reactions of ZnS and ZnS/CdS Co‐Colloids

AbstractSmall colloidal particles of ZnS were obtained by precipitation of Zn2+ with SH− in the presence of colloidal silicon dioxide. Co‐colloids were prepared by simultaneously precipitating ZnS and CdS. Colloidal ZnS fluoresces at 425 nm. 90% of the fluorescence decays within 30 ns. The fluorescence is partly quenched by oxygen, chloroethanol and chloralhydrate. It can be completely quenched by methyl viologen and sulfide anions at low concentrations. The quenching actions are attributed to the scavenging of electrons or positive holes which are photo‐generated in ZnS. The onset of the absorption and the maximum of the fluorescence band are shifted towards shorter wavelengths with increasing Zn/Cd ratio of the co‐colloid. – ZnS in deaerated solution undergoes a slow photo‐anodic dissolution (quantum yield ø = 2 · 10−3 ZnS molecules/photon), the products being H2, Zn2+ (aq), sulfur and SO (aq). In the presence of air, a rapid decomposition with ø = 0.32 ZnS/photon takes place. In deaerated solutions, chloroorganic compounds promote the dissolution of ZnS. The chloroorganic compounds are decomposed, too. In the presence of sulfite, zinc metal is photo‐deposited onto the colloidal particles until hydrogen production takes over with ø = 0.18 H2/photon. In the presence of both sulfite and carbon dioxide, formic acid is produced with ø = 0.2 HCOOH/photon.

Biodegradation of Recalcitrant Organochlorine Compounds in Fixed Film Reactors

Biodegradation in fixed film reactors of chloroorganic compounds in kraft bleaching effluent and in pesticides was studied. Specific biofilm reactors could be adapted for the mineralization of chloroform, chlorophenols, chlorocatechols, chloroguaiacols, chloroveratroles and chlorinated resin acids in bleaching effluent and for chlorophenols in spills of pesticides for blue stain and wood rot. Mineralization of chloroorganic compounds into inorganic chloride and carbon dioxide occurred in the solid phase of the reactor. The ability to degrade the chlorine compounds could be transferred from one reactor to another by transferring the liquid but no degradation occurred before addition of solids in the reactor. The degradation of pentachlorophenol was most active when softwood bark was used as the solid material It was less active on unglazed pottery, and inactive on glass (beads or fibre), cellulosic fibre, clay and ion exchange resin. The mineralization of the chloroorganics occuring in kraft bleaching effluent was less fastidious about the type of solid materials used. The biofilm grew equally well on softwood bark, ion exchange resin and various types of plastic and fiber.

クラフトパルプの漂白廃水成分およびその毒性

This paper deals with the identification of low molecular weight compounds in spent chlorination liquor of kraft pulp, and the evaluation of acute toxicities of various bleaching effluents and their components. Thiolignin and holocellulose were used as the model substance of unbleached kraft pulp components.The results are as follows : 1) The major components in spent chlorination liquor of thiolignin were oxalic acid and chloro-aliphatic acids.2) Dichloromaleic acid and trichloroacetic acid were newly identified in spent chlorination liquors. These are originated from lignin in unbleached kraft pulp.3) In the chlorination stage chloro-organic compounds are not originated from carbohydrate. The major components in spent chlorination liquor of holocellulose are glycolic acid and glyceric acid.4) The toxicity of each spent liquor to Himedaka (Oryzias latipes) is in the increasing order of AP liquor (spent alkaline extraction liquor of chlorinated pulp), AL liquor (spent alkaline extraction liquor of chlorinated lignin), CL liquor (spent chlorination liquor of thiolignin), and CP liquor (spent chlorination liquor of kraft pulp).5) Aliphatic acids, except chloromaleic acid and chlorofumaric acid, in spent chlorination liquors showed no toxicity. They are hardly responsible for the toxicity of bleaching effluents.

Catalyst for fluorination of organic chlorocompounds

A procedure for the preparation of a catalyst for fluorination of organic chlorocompounds is described. It is based on precipitation of chromic hydroxide from a diluted solution of a chromic salt under suitable conditions of concentration, temperature and pH. The chromic hydroxide, washed up to complete removal of ionic impurities, was dried and calcined under controlled temperature conditions. The chromic salt giving the oxide with the most satisfactory physical and catalytic properties was chromic-potassium sulphate. The chromic oxide thus prepared exhibited long catalytic life in the gaseous fluorination with hydrogen fluoride of various organic chloro-compounds, such as CCl4, CHCl3, CH2Cl2, C2Cl6, C2HCl5, C2HCl3, C2Cl4, C2Cl3F3, C2Cl2F4, CF3CH2Cl, CCl3COCCl3.

Reduction pathways of organohalogen compounds Part III. A molecular orbital (CNDO/2) study of the chlorinated benzenes, DDT, and lindane

Molecular orbital calculations, using the CNDO/2 method which treats both the σ and π systems of molecules, were carried out for all the chlorinated benzenes, DDT (1,1,1-trichloro-2,2-bis-( p -chlorophenyl)ethane), lindane ( γ -1,2,3,4,5,6-hexachlorocyclohexane) and γ -BTC ( γ -3,4,5,6-tetrachlorocyclohexene). The energy level and electron distribution for the lowest unoccupied molecular orbital (LUMO), both LUMO- σ and LUMO- π when each system is present in the molecule, were compared with the electrochemical behavior of these compounds. The energies of both the LUMO- σ and LUMO- π are about equal and each give a linear correlation with reduction potentials for all the chlorinated benzenes. However, the CNDO/2 calculations for their respective radical anions show that the electron has entered the σ orbital. The LUMO- σ is antibonding with the electron density localized in the C−Cl bonds which undergo cleavage to the reduction products. The relative electron density for different C−Cl bonds correlates with the product ratios when several products are found. The evidence indicates that upon electrochemical reduction of chloro organic compounds the first electron should enter the LUMO- σ , even if there is a π system available.