Mercury In Wastewater Research Articles

Flow-through stripping chronopotentiometry for the monitoring of mercury in waste waters

A simple method for the determination of total mercury in waste waters is described. It makes use of a flow system incorporating a wall-jet cell equipped with a gold working electrode. The untreated sample is mixed on-line with the acidic carrier electrolyte which contains potassium permanganate and transforms the various species of mercury, especially elementary Hg, to Hg(II). The pre-treated solution enters the cell where mercury is deposited on the gold electrode. In the next step the deposit is stripped at constant current and the time corresponding to the dissolution of the deposit is obtained from the chronopotentiometric signal. The method enables it to determine and monitor Hg in the concentration range of 1 to 1000 μg/L in 5 min intervals.

Spectrofluorometric method for determination of the total mercury content in environmental samples — Waste waters

A highly selective spectrofluorometric method for the determination of total mercury (Hg) in waste waters is described. Fluorescence quenching of rhodamine B with Hg(II) in the presence of iodide, after a concentration step, is the basis of this sensitive method. All forms of mercury, including organic compounds, are pre-oxidized to ionic mercury by acidic potassium permanganate. The final and complete oxidation is achieved by adding potassium persulphate and heating. Hg(II) was reduced by tin(II) chloride and Hg vapour driven by an air stream into an absorption solution containing potassium permanganate and sulphuric acid, using a closed, recirculating air stream. In this solution fluorescence quenching of rhodamine B at an excitation wavelength of 485 nm and emission wavelength of 586 nm was measured. The recoveries were done by adding 3.0 μg Hg/100 ml to each sample before the digestion. It was indicated that the recoveries for determining mercury in waste waters were 98.3%–102.7%. The method gives reliable results down to a concentration of 10 ng Hg/ml waste water.

Spectrophotometric Determination of Trace Amounts of Mercury(II) in Waste Water with p-Azobenzenediazoaminoazobenzene Sulfonic Acid

Abstract A new method for the direct determination of trace mercury in aqueous solution with high selectivity and sensitivity is reported. In the presence of Triton X-100 and NH3.NH4Cl medium, a new chromogenic reagent p-azobenzenediazo- aminoazobenzene sulfonic acid (ADAAS) forms a red complex with mercury(II). The molar absorptivity is 1.76×105 l. mol−1 cm−1 at 528 nm. Beer's law is obeyed in the range of 6.0×10−8 - 6.0×10−6 mol/L for Hg(II). Only cadmium interferes in the determination of mercury, and it can be eliminated by masking with nitrilotriacetic acid. The proposed method has been successfully used for the determination of trace amounts of mercury in waste water.

Mercury determination by CV-AAS in wastewater and sewage sludge from a stabilization pond system.

The mercury concentrations in wastewater and sewage sludge of a stabilization pond system have been evaluated. The system is built by three parallel facultative ponds followed by two systems of three maturation ponds in series. The samples of wastewater and sludge were digested using nitric acid and placed into a Parr-type bomb for 4 h at 110 degrees C. Mercury was measured by Cold Vapour Atomic Absorption Spectrometry (CV-AAS) at 253.7 nm with sodium tetrahydroborate as reductant. The methodologies were checked with an USEPA quality control sample, a standard reference material from NIST and with another method of mineralization (cold mineralization) showing good results. Concentrations of mercury in wastewater between 1.47 +/- 0.75 microgl(-1) have been found at the entrance of the system and 0.74 +/- 0.0 microgl(-1) at the exit, while in sludge the results were between 0.29 +/- 0.12 microgkg(-1) in the facultative pond and 0.04 +/- 0.02 microgkg(-1) in the second maturation pond (exit).

Studies on the Synergistic Effects of Metal Cations on Kinetic Reactions and Their Analytical Applications

The synergistic or mutual catalytic effect between metal cations such as molybdenum(VI) and tungsten(VI), silver(I) and mercury(II), and iron(II) and antimony(III) on different kinetic reaction systems had been studied spectrophotometrically with a stopped flow-FIA technique. The degree of synergistic effect was expressed by the proposed synergistic catalytic coefficientD.The deviations of absorbance from additivity of outside certain concentration ranges could be compensated, for by introducing the synergistic coefficient into the procedures for simultaneous determination of a binary mixture with the stopped flow-FIA method proposed previously, and the linear concentration ranges could be enlarged by compensating. Molybdenum and tungsten in steel, iron and antimony in a zinc standard, and silver and mercury in wastewater had been determined, and the results are satisfactory.

Determination of mercury in environmental and biological samples by cold vapour atomic absorption spectrometry

A continuously operating monitoring method for total mercury at sub-ng/ml level in environmental and biological samples by cold vapour atomic-absorption spectrometry with NaBH4 as a reductant was developed. The mercury vapour generator and absorption cell closed-end by quartz were used in this study. The detection limit (S/N = 3) and relative standard deviation of 12 determinations of 10 ng/ml Hg(II) were 0.11 ng/ml and 1.1%, respectively. The range of standard calibration curve was 0–50 ng/ml Hg, The proposed method was successfully applied to the completely continuous monitoring of total mercury in waste water, sediments and pork liver.

1-(4-nitrophenyl)-3-(2-quinolyl) triazene as an extremely sensitive reagent for spectrophotometric determination of mercury

1-(4-Nitrophenyl)-3-(2-quinolyl)triazene has been synthesized, and used as an extremely sensitive reagent for the spectrophotometric determination of mercury by the decrease in the absorbance of the reagent at 490 nm and pH 9.0–10.8 in the presence of cetylpyridinium bromide. Beer's law is obeyed over the range 0–120 ng/ml Hg(II), the apparent molar absorptivity being 1.0 × 10 6 l.mole −1.cm −1. The effect of 69 ionic species or compounds has been examined. Trace mercury in waste water has been determined satisfactorily.

The Pollution of Minamata Bay by Mercury

Minamata Disease, methylmercury poisoning, was recognized late in 1953 among the inhabitants living around Minamata Bay. In a chemical factory situated near Minamata Bay, acetaldehyde had been synthesized by the hydration of acetylene till 1968; in the reaction mercury oxide dissolved in sulfuric acid had been used as a catalyst. Inorganic mercury in waste water from the acetaldehyde plant had been discharged into the bay and it had accumulated into bottom sediment. It was proved that a part of inorganic mercury used as the catalyst had changed into methylmercury by a sidereaction in the plant and waste water containing methylmercury from the plant had discharged into the bay and methylmercury had accumulated into the fishes. The mercury concentrations in the muds were very high: in 1963, 29~713 ppm (dry weight); in 1969, 19~908 ppm (dry weight); in 1970, 8~253 ppm (dry weight) and in 1971, 14~586 ppm (dry weight). Since 1977, dredging work had been carried out to remove mercury-contaminated mud and all of the work had finished at March 1990. The concentration of mercury in fishes from the bay was very high in 1959: shellfishes 108~178 ppm (dry weight) and fish 15 ppm (wet weight). Mercury concentration in fishes has decreased markedly since 1966. Total mercury concentration in fishes (87 species) were 0.01~1.74 ppm (wet weight) and fishes containing over 0.4 ppm of total mercury were 16 species in 1989. The hair of patients contained a high concentration of mercury, the highest being 705 ppm. In 1968, the average mercury concentration in patients was 10.6 ppm, for fishermen, the average was 9.2 ppm, and for general inhabitants, the average was 8.1 ppm. In 1982, the average methylmercury concentration in fishermen was 6.15 ppm and for general inhabitants, the averge was 3.78 ppm. Thus, the mercury content in hair decreased gradually with time. After treatment of mercury in waste water was initiated, the mercury content in fishes from Minamta Bay was gradually reduced. It is necessary to supervise strictly to avoid mercury pollution of the environment.

Enhancement effect of iron addition for the decomposition of organic mercury as studied by continuous flow analysis with cold vapor atomic absorption spectrometric detection

A continuous flow analysis is described for the determination of total mercury by cold vapor atomic absorption spectrometry. Organic mercury compounds such as methylmercury(II) chloride, ethylmercury(II) chloride and phenylmercury(II) chloride were decomposed by potassium peroxodisulphate with addition of ferric chloride as catalytic reagent. The reducing reagent used was tin(II) chloride in sodium hydroxide solution. With 1,000 mg Fe/l added in the decomposition process, we found that methylmercury(II) chloride and ethylmercury(II) chloride gave response signals similar to those of mercury(II) chloride. The proposed method was applied to the analysis of total mercury in waste water.

A Continuous Monitoring System for Total Mercury in Waste Water by Cold Vapor Atomic Absorption Spectrometry and Continuous Microflow Analysis

An automated system based on «continuous microflow analysis» and cold vapor atomic absorption spectrometry has been developed for monitoring the concentration of total mercury at sub-μg/l levels. The method involves a continuous microflow technique for sample digestion, reduction and extraction in small bore tubes (0.5 mm i.d.) at μl/min flow rates of reagents. Sodium tetrahydroborate in sodium hydroxide solution was used as the reducing reagent. In the case of discrete injection of sample (200 μl), analysis time for the determination of total mercury was about 3 min per sample

A simple determination of mercury by cold-vapor atomic absorption spectrophotometry in alkaline for the samples co-existing organic substances.

The simple method by cold-vapor atomic absorption spectrophotometry was studied for the samples co-existing organic substances by the rapid determination of mercury using alkaline tin (II) reduction. It is known that in the presence of tin (II) organomercury compounds such as methyl-, ethylmercury chloride and phenylmercury nitrate are reduced to inorganic mercury (II) in alkaline with a certain amount of copper (II) ion. But the reduction of organomercury compounds cannot proceed in the presence of potassium zinc cyanide as a masking agent for silver ion which is effective for the complicated environmental samples. However, the present paper shows that the addition of a large amount of copper (II) ion resolved this complicated problem. The reason for the remarkable effect of copper (II) ion was on the reduction of organomercuy compounds was therefore discussed. These aspects gave a simple method without time-consuming pre-treatment step in the samples which contained several organic substances. This method was applied for the determination of mercury in wastewater or biological samples with satisfactory results. The detection limit and precision of this method were 0.2 μg/l and 3%, respectively.

Automated continuous monitoring of inorganic and total mercury in wastewater and other waters by flow‐injection analysis and cold‐vapour atomic absorption spectrometry

An automated continuous monitoring system for the determination of inorganic and total mercury by flow-injection analysis followed by cold-vapour atomic absorption spectrometry is described. The method uses a typical flow-injection manifold where digestion and reduction of the injected sample takes place. Mercury is removed by aeration from the flowing stream in a specially designed air-liquid separator and swept into a silica cell for absorption measurement at a wavelength of 253.7 nm. A calibration curve up to 10 μg Hg ml-1 using three different path length cells is obtained with a detection limit of 0.02 μg Hg ml-1. The sampling rate of an injection every 3 min produces 20 results per hour from a flowing stream.

Continuous monitoring of total and inorganic mercury in wastewater and other waters

An automated continuous monitoring system for the determination of total as well as inorganic mercury by cold-vapor atomic absorption spectrometry is described. The method uses continuous flow digestion, reduction and extraction in small bore tubes at slow flow rates, and is suitable for use in the analysis of wastewater and natural waters. A detection limit of 0.1 ppb is obtained when a specially designed, complete gas—liquid separator is used with a condenser circulated with ice-chilled water for removing water vapor, and an 8-μl flow cell for detection. The response times for the determination of inorganic and total mercury are about 3 and 5 min, respectively. The amount of reagents required is about one-tenth of that in conventional Auto-Analyzer methods.

Investigation of the use of cuprous iodide for the removal of mercury in wastewater

Investigation of the use of cuprous iodide for the removal of mercury in wastewater

Mercury Pollution in Dental Practice

A recent problem is mercury pollution of river and fish, and the allowable level of mercury in waste water has been fixed at below 5 ppb. Environmental mercury contamination through dental procedures, especially through waste water from dental offices, was studied and the following results were obtained.1) High levels of mercury were contained in saliva vacuumed from the oral cavity during amalgam filling, but mercury levels were decreased by using a net bag for removal of amalgam scrapings.2) Mercury was detected in all waste water from dental practice, such as saliva vacuumed from the oral cavity, water gargled after amalgam filling, waste water from the dental unit, and the final waste water from dental offices. As the amount of flowing waste water increases, mercury levels in waste water decrease. But the amount of mercury discharged from dental practice through waste water was not small.3) Mercury levels in final waste water from dental offices were at an average of 11.3 ppb. The final waste water of almost all dental offices exceeded the allowablelevel (5 ppb).4) Mercury levels in soil around dental offices, and even in soil of houses next to dental offices, was higher than control houses. Then it was shown mercury contamination in dental practice was caused not only through waste water but also through the atomosphere.5) Very high levels of mercury was contained in soil soaked in waste water from dental offices and in sludge from drain-pipes of dental offices. It was shown that soil and sludge absorb and concentrate mercury in waste water.6) There is almost no risk that mercury metal discharged from dental offices will be converted to more poisonous methylmercury by the action of microorganisms in soil and sludge.A large amount mercury metal is discharged from dental offices, and it is absorbed, accumulated, and concentrated to very high levels in soil and sludge. Therefore we should strive to find a practical method of extracting mercury from dental waste water.

Hygienic Chemical Studies on Mercury. III. Rapid Flameless Atomic Absorptiometric Determination of Organic Mercury by Quartz Tube Combustion-Gold Amalgamation Method

A simple and sensitive method for the quantitative determination of organic mercury in waste water, fish tissues, and sea or river bottom sediments is described. This method consists of extraction of organic mercury from the material with benzene, reverse-extraction of the organic mercury with cysteine acetate solution, and combustion of the solution in the system described earlier. This method has the following features : (1) It is not necessary to use organic mercury such as methylmercuric chloride, ethylmercuric chloride, butylmercuric chloride, or phenylmercuric acetate, as the standard substance in the determination of organic mercury compounds, and inorganic mercuric chloride can be used as the standard in this method. (2) Organic mercury compounds can be completely separated from inorganic compounds by using benzene and cysteine acetate solution. (3) Analytical values of organic mercury compounds obtained by the proposed method agree completely with that obtained by the gas chromatographic analysis with electron captuer detector (ECD-GC method). (4) In carrying out this proposed method, it is not necessary to obtain any licence for handling radioactive rays which is required in the case of the ECD-GC method. Satisfactory results have been obtained by applying this proposed method to the analysis of organic mercury in various materials.