Atomic Adsorption Spectrometer Research Articles

Evaluation of the content of ceruloplasmin, copper and coppercoordinating amino acids in cow milk at different lactation periods

The purpose of the research was to study the content of ceruloplasmin, copper and copper-coordinating amino acids (in the molecule of the studied protein) in the milk of white-and- black cows at different periods of lactation. The research methods were: modified method for determining ceruloplasmin by Revin; copper was determined using a ZEEnit 650 P atomic adsorption spectrometer (Analytik Jena AG, Germany), amino acid analysis was performed using a highly efficient LC-20 Prominence liquid chromatography system (Shimadzu, Tokyo, Japan) equipped with a reaction module for post-column derivatization with ninhydrin ARM-1000 (Sevko & Co., Moscow, Russia). The study groups were formed depending on the timing of lactation: 1-2 months – group 1; 3-5 months – group 2; 6-7 months – group 3; 8-9 months – group 4. Each group included 8 animals. The Mann-Whitney U criterion and Pearson correlations were used for statistical processing of the obtained results. The average values of ceruloplasmin levels in the groups were 0.44-0.49 mg/ml, copper 71-83 mcg/l, histidine 0.11-013 g/100g, cysteine 0.03 g/100g and methionine 0.09-0.11 g/100g. In these 4 groups, small differences were found in the content of ceruloplasmin, copper and three amino acids, but only for the second and fourth groups of histidine, these differences were significant. Thus, the indicated intervals of ceruloplasmin and copper content can serve as important guidelines for determining the "reference intervals" for cow milk in general, while it is not necessary to take into account different lactation periods.

Ecological and human risk assessments of heavy metal contamination of surface soils of auto-mechanic shops at Bogoso Junction, Tarkwa, Ghana.

There is a growing recognition that activities at automobile mechanic shops could contribute to heavy metal contamination of soils. This study seeks to evaluate the ecological and human risk assessments of heavy metal contamination of surface soils of auto-mechanic shops at Bogoso Junction, Tarkwa, Ghana. Herein, 20 composite soil samples were taken, acid-digested, and the concentrations of Cu, Pb, Cd, Mn, Ni, Cr, and Fe were measured using a flame atomic adsorption spectrometer (SHIMADZU, AA 7000). Appraising metal pollution indices, the potential human and ecological risks associated with analyzed metals were carried out. Findings of the present study indicate that the levels of analyzed metals of soils exceeded the control soil sample and the European Union standards for soil quality. The mean metal concentration increased in the order Fe > Mn > Cu > Ni > Pb > Cr > Cd in the soils. Outcomes of enrichment factor, geo-accumulation index, and contamination factor revealed that the soil quality is deteriorated with Cu, Pb, and Cd. The potential ecological risk identified Cd and Pb as the richest elements and offered a high ecological risk in all sampling sites. Furthermore, hazard quotient of analyzed metals depicted that Ni and Mn in urban soils of Bogoso Junction automobile mechanic shops may pose a threat to children (HI > 1). Dermal contact and inhalation of soil particles are the main exposure routes for children susceptibility. Specifically, cancer risk associated with Cd inhalation was 10 times greater than oral ingestion of Pb, showing a relatively high carcinogenic hazard to humans. Altogether, artisanal activities such as engine repair, welding and soldering, vehicle overhauling, and oil exchange at the automobile mechanic shops could deteriorate the soil quality resulting in ecological and human health implications within the vicinity of automobile mechanic shops in Ghana.

Structural and Surface Modification of Oxalic-Acid-Activated Bentonites in Various Acid Concentrations for Bleaching Earth Synthesis—A Comparative Study

The aim of this study is to investigate the oxalic acid activation of bentonites containing different types of smectites, analyse their surface modification as a function of acid concentration and create good quality bleaching earths. In particular, two different bentonite samples (one containing aluminum and one containing ferruginous smectite), after being characterized through XRD, XRF and FT-IR analysis, are treated with oxalic acid at a concentration of 0.5, 0.7 and 1 M. Their structural modifications after treatment are observed through FT-IR spectra and surface area and porosity measurement (using the BET equation and the BJH method, respectively) combined with the determination of the main structural metals’ extraction from them (using an atomic adsorption spectrometer). The results showed that the ferruginous smectite is more susceptible to oxalic acid activation compared to the aluminum smectite, and all the final products have developed extra porosity in their structure while retaining the structure of smectite (even at 0.5 M acid concentration). The activated samples were used as bleaching earths in soybean oil, and the results proved that Lovibond yellow and red colours as well as the chlorophyll of oil (measured spectrophotometrically) were reduced to the values set by the specifications.

Flame retardant polyacrylonitrile fiber modified with hydrazine hydrate and copper ions

The limiting oxygen index (LOI) of polyacrylonitrile (PAN) fiber is only around 18%, making it urgently needed to enhance flame retardancy. Treatment with hydrazine hydrate as cross-linking agents followed by adsorption of metal ions endows PAN fibers with excellent flame retardancy. The Fourier-transform infrared spectroscopy (FT-IR) was employed to investigate the evolution of the chemical structure of the fibers. The atomic adsorption spectrometer (AAS) was carried out to study the adsorption capacity for copper ions. The wide-angle X-ray diffraction (WAXD) and scanning electron microscope (SEM) were used to study the aggregate structure and morphology of the fibers. In addition, LOI, thermogravimetric analysis/infrared spectrometry (TG-FTIR), and thermogravimetric analysis (TGA) were employed to clarify the flame-retardancy and the mechanisms. The mechanical property was studied via a single fiber tensile tester. The results showed that more chelating groups arose in macromolecular chains of PAN fibers after the reaction with hydrazine hydrate, with increased adsorption capacity for Cu2+. The LOI reached 24.0% after the treatment of hydrazine hydrate and the fiber was still flammable in the air. After the treatment with metal ions, the LOI of the fibers dramatically rose to 45.2%. The thermal decomposition process differed after the treatment of hydrazine hydrate, resulting in a more violent release of ammonia and a sharp reduction of flammable gases. The introduction of copper ions made fibers form dense carbon residue during thermal decomposition, which was beneficial for the improvement of flame retardancy.

REMOVAL OF HEAVY METALS FROM WASTEWATER BY USING PHYTOREMEDIATION TECHNOLOGY

Contamination of soil and water by toxic metals is a major environmental hazard. The removal of heavy metals from wastewater by chemical methods is very costly and does not apply to the pretreatment process. Hence, phytoremediation process is one of the simplest methods to restore polluted environments. The present research paper investigates the potential of Mimosa Pudica for bio removal of heavy metals like Cd, Pb and Cu from wastewater by using phytoremediation or bioremediation technology. Heavy Metals were detected before and after the process using Atomic Adsorption Spectrometer (AAS). The synthetic wastewater contains Cd, Pb, and Cu at an initial concentration of 0.25mg/l, 0.5mg/l, and 2mg/l was introduced to the soil mass planted by Mimosa Pudica and treated for 16 days through their root. Collected samples were taken for laboratory analysis. The result showed that there was a reduction in Cd, Pb and Cu at a concentration of 0.02mg/l, 0.21mg/l, and 0.4mg/l level of heavy metals from the wastewater. After that, investigation of the potential of Mimosa Pudica accumulates up to 92% of Cd, 58 % of Pb, and 80% of Cu. The evidence presented by this study specified that Mimosa Pudica is an efficient accumulator plant for phytoremediation or bioremediation.

Evaluation of the efficacy and optimization of indigenous microbial isolate for herbicides (Paraquat Dichloride, Glyphosate, and Glyphosate isopropylamine) degradation

The presence of herbicides in soil is a serious problem for the environment. Studies on degradation of Herbicide (Paraquate dichloride (PD), Rake out (RO) and Gobara (GB)) by bacteria and fungi species isolated from soil environment in Keffi Metropolis Nigeria were carried out. A total of twenty (20) soil samples were collected. The bacteria and fungi were isolated from the soil and identified using standard microbiological methods. The herbicides utilization was determined using Atomic Adsorption Spectrometer. The effect of temperature on utilization of the herbicides by Enterobacter asburiae at 26OC ranges from 1.23±0.11 mg/ml for PD, 1.14±0.29 mg/ml for RO and 0.53±0.86mg/ml for GB, Pseudomonas aeruginosa utilization ranges from 1.45±0.17 mg/ml for PD, 1.17±0.35 mg/ml, for RO 1.12± 0.82mg/ml for GB. Aspergillus flavus ranges from 2.12±0.19 mg/ml for PD, 2.00±0.03 mg/ml for RO and 2.02±0.57 mg/ml for GB, Fusarium redolens were 2.19±0.26 mg/ml for PD, 2.15±0.08 mg/ml for RO and 1.92±0.16 mg/ml for GB. Effect of incubation time on microbial herbicides degradations: for E. asburiae on PD it ranges from day 1 with 0.24±0.37 mg/ml to day 20 with 2.06±0.11 mg/ml. for P. aeruginosa on PD ranges from day 1 with 0.38±0.08 mg/ml to day 20 with 2.39±1.45 mg/ml. The Utilization of herbicides by A. flavus on PD ranges from day 1 with 0.10±0.01 mg/ml to day 20 with 2.29±0.12 mg/ml. for F. redolens in PD, it ranges from day 1 with 0.27±0.08 mg/ml to day 20 with 2.57±0.27mg/ml. The process of degradation of herbicide has become very attractive as it allows for removal of herbicide over a relatively broad range of pH and temperature

Circulatory cadmium positively correlates with epithelial-mesenchymal transition in patients with chronic obstructive pulmonary disease

Environmental cadmium (Cd) exposure can cause several pulmonary diseases. Epithelial-mesenchymal transition (EMT) involved in the process of chronic obstructive pulmonary disease (COPD). However, the association between environmental Cd exposure and EMT was unclear in COPD patients. This study aimed to analyze the associations among circulatory Cd, EMT and COPD based on case-control study. Four hundred COPD patients and 400 control subjects were recruited. Circulatory Cd was detected using atomic adsorption spectrometer. MicroRNA-30 (miR-30) was measured by RT-PCR and the markers of pulmonary EMT were evaluated through western blotting. Circulatory Cd concentration was increased and serum miR-30 was decreased in COPD patients. Circulatory Cd was inversely associated with pulmonary function in COPD patients. Moreover, serum miR-30 was gradually decreased in parallel with FEV1 in COPD patients. Meanwhile, there was a negative association between serum miR-30 and circulatory Cd in COPD patients. Further analysis found that E-cadherin, one of epithelial biomarkers, was reduced in lung tissues of COPD patients with higher circulatory Cd. On the contrary, pulmonary N-cadherin, Vimentin and α-SMA, three of mesenchymal biomarkers, were increased in COPD patients with higher circulatory Cd. In vitro experiments revealed that Cd exposure repressed miR-30 levels and promoted EMT in BEAS-2B cells. Our results provide evidence that miR-30 reduction contributing to pulmonary EMT may involve in the process of Cd-induced COPD.

ASSESSMENT OF MIGRATION OF HEAVY METALS (Cd, Pb, As, Hg) IN THE SYSTEM «FEED - MILK»

The article presents the results on the level of migration of heavy metals in the food chain «feed-milk» of the farm «Aidarbayev», located in the Almaty region. A total of 56 feed samples and 30 milk samples were analyzed during the study period. Sampling from the facilities was carried out in the spring, summer and autumn of 2020 in accordance with the State Standards of the Republic of Kazakhstan and interstate standards. Work on determining the concentration of heavy metals was carried out on a novaa 350 atomic adsorption spectrometer with a talab voltammetric analyzer (Germany) at the Kazakhstan-Japan Innovation Center. It is proved that the increase in the concentration of cadmium, lead, mercury and arsenic in the daily diet of cows in winter or summer pasture periods is proportional to the increase in their content in milk. It was found that the level of heavy metals (Cd, Pb, As, Hg) in feed and milk does not exceed the MPC. The results obtained can serve as a basis for monitoring the state of the environment on the content of heavy metals in natural objects of the country.

Study of Heavy Metals Variability and their Effect on Plant Growth in Kanzenze River of Upper Akagera Catchment, Rwanda

Agricultural swamps are among the major fruitful and exposed to heavy metals deposition and contributes to ecological concerns. Heavy metals are mainly pollutants to deteriorate water quality and affect plant health through leaching and seepage process from industrial services, anthropogenic activities, erosion and mining activities. The study aimed to assess heavy metals, water quality and their effect on plant growth along Kanzenze Swamp of the Akagera Upper Catchment. The total of Sixteen chemical parameters of water including Calcium, Magnesium, Sodium, Potassium, Copper, Zinc, Manganese, Lead, Cadmium, Chromium, pH, Electrical Conductivity, Sodium Adsorption Ratio, Magnesium hazards, Kelly Index and Soluble Sodium Percent were analyzed and observed values were thereafter compared with international standards values recommended by Food and Agriculture Organization. Photometric methods and Atomic Adsorption Spectrometer machines were used to detect the heavy metals while analytical. Descriptive analysis and Principal Components Analysis techniques were used to correlate water quality parameters for similarities and dissimilarities through cluster analysis. All statistical analysis were performed by using Statistical Package for Social Science version 22.0. The study findings shows that most water use for irrigation is polluted by heavy metals with maximum values compared to Rwanda national and international permissible standards for irrigation. The heavy metals with highest content included Calcium, Magnesium, Potassium, Copper, Manganese, Cadmium and Chromium. Hence farmers relaying on this water may be disposed to health hazards issues and other environmental concerns. Therefore some effective measures like water treatments are compulsory vital needed to boost the quality of water for irrigation purpose.

Assessment of Heavy Metal Pollution of Water, Sediments and Algae in River Benue at Jimeta-Yola, Adamawa State, Nigeria

Heavy metal pollution of water, sediments and Algae in the upper region of River Benue at Jimeta-Yola, Adamawa state, Nigeria was assessed. The concentrations of the heavy metals (Pb, Hg, Ni, Cu, Cr, Zn, Mn, Fe) in the samples were analyzed using Atomic Adsorption Spectrometer. Pollution parameters such as enrichment factor, contamination factor, pollution load index and geo-accumulation index were evaluated. The result of heavy metal analysis showed that, the concentration (ppm) of the metals in water samples ranged as follows: Pb(0.25-0.50), Hg(0.00-2.00), Ni(0.10-0.31), Cu(0.03-0.13), Cr(0.00-1.33), Zn(0.01-0.04), Mn(0.03-0.06) and Fe(105.15-118.75) respectively. This result when compared with the EPA maximum permissible limits for drinking water showed that, all the metals except Cu and Zn had values above the permissible limits. The evaluation of enrichment factor revealed that, Hg showed extremely high enrichment while Pb showed significant enrichment for Algae, water and sediment samples. The contamination factor showed low contamination for all metals except Hg which showed considerable contamination for sediments, water and Algae samples. The pollution load index for sediments, water and Algae indicated no pollution. The geo-accumulation index of the metals in sediments, water and Algae indicates no or minimal pollution. The samples were enriched with Hg and Pb. These metals are capable of causing various types of cancer, brain and kidney damage among other ailments.

Diurnal fluxes of gaseous elemental mercury from the water-air interface in coastal environments of the northern Adriatic Sea

A crucial step towards developing a more complete understanding of mercury (Hg) biogeochemical cycling in coastal environments is the measurement of the fluxes of gaseous elemental mercury (GEM), at the water-air interface (W-A interface). A floating flux chamber coupled with a real-time atomic adsorption spectrometer (Lumex-RA 915M) was applied to measure GEM concentrations, and to estimate the diurnal evasion flux at the W-A interface during three seasonal campaigns at four selected sites: two in a lagoon-based fish farm, one in an open lagoon environment highly impacted by long-term activities from the Idrija mercury mine (Slovenia), and an uncontaminated area of the Gulf of Trieste, the Bay of Piran (Slovenia). In this study, the regional background concentration measured at the uncontaminated site of atmospheric GEM (from 1.60 ± 0.95 to 2.87 ± 1.52 ng m−3) was determined. GEM fluxes at the W-A interface were found to be significantly higher during the summer (from 51.2 ± 8.8 ng m−2 h−1 to 79.9 ± 11.4 ng m−2 h−1) and correlated to incident solar radiation and water temperature. This finding confirms the importance of these two parameters in the photoreduction and biotic reduction of Hg2+ to dissolved gaseous mercury (DGM), which is volatile and easily released to the atmosphere in the form of GEM. These new insights will be of help for future estimates of Hg mass balance in one of the most contaminated areas in the Adriatic Sea.

Physico-chemical and Concentration of Heavy Metals Analyses in Virgin and Used Lubricating Oils: A Spectroscopy Study

As a result of the changes that occur during their use, lubricating oils from automobiles tend to differ in terms of their physical and chemical composition from virgin and used lubricating oils. The analyses of the heavy metals distribution, contaminants and physicochemical parameters of the virgin and used lubricating oils will guide us to select the possible processes that can alter the oil composition. This research examines the heavy metals distribution, contaminants and physicochemical parameters of the virgin and used lubricating oils using Atomic Adsorption Spectrometer for 7 elements using various ASTM D methods. The results obtained shows that there were significant differences in the virgin and used lubricating oils. The deleterious effects of heavy metals, contaminants and physicochemical parameters on the environment have been known for a while. These contaminants not only causes environmental problems, they also have bio-accumulation effects on living organism, poisoning and fouling of catalyst as well as corrode processing equipment. This study also presents results showing us that contaminants, heavy metals and physicochemical parameters play a major role in discriminating of lubricating oil samples.

Effect of Pyrolysis Temperature on Cadmium and Lead Concentration Distribution of Some Selected Tobacco Cigarettes in Nigeria

Consumption of tobacco as cigarette or otherwise has been demonstrated to contribute to air pollution via smoke generation resulting in adverse health effect. Therefore, this study investigates the effect of pyrolysis temperature on the concentration, distribution of cadmium and lead between ash residue and smoke in some selected cigarettes in Nigeria. Four samples consisting of three different brands of cigarette, Benson, Excel, London and fresh tobacco leaves were considered. Each of the samples was pyrolyzed at different temperatures of 300, 400 and 500°C and ash residues were collected and digested for determination of cadmium and lead concentrations using atomic adsorption spectrometer consequent upon which concentration in the smoke were calculated. For all the samples considered, it was observed that increasing the pyrolysis temperature from 300 to 500°C resulted in a decrease in concentration of cadmium and lead in ash residue and an increase in concentration of cadmium and lead in the smoke. Key words : Tobacco, cigarette, ash residue, smoke, combustion.

The Use of Scallop Shell Powder As a Method of Extracting Alkaline-Earth Metals

Introduction Approximately 260,000 tons of scallop shells become industrial waste[1] every year in Japan. So far, attempts to reuse the shells have been mainly limited to the commercial production of CaCO3. Currently, almost all CaCO3 in Japan is produced from limestone. Each year in Japan, 200 million tons of limestone is mined[2]. CaCO3 produced from limestone is less expensive than that produced from scallop shells. There are no obvious economical benefits to using scallop shells as a source of CaCO3. Therefore, we are attempting to find a new value added use for scallop shells as an advanced functional material. In previous experiments[3], we have been trying to use calcined shell powder to extract alkaline metal and alkaline-earth metal from seawater. The tsunami of March 11, 2011, caused severe damage to the Fukushima nuclear power plant. Today, many problems still exist, but a particularly serious problem is the leakage of highly toxic contaminated water. Within the storage tanks, there remains a large quantity of contaminated water. This water contains radioactive Sr2+ and Cs+. Sr2+ tends to accumulate in bones and is believed to because of bone cancer. Therefore, it is highly desirable to develop a method for the removal of Sr2+ from the contaminated water. Here we will show the potential of scallop shells to adsorb Sr2+ from the solution. Experimental First, we crushed the shells using a stamp mill and an automatic grinder. Next, we classified the shell powder by sieves according to their diameter. Then, we put the shell powder into a beaker with a solution (including Sr2+) and stirred it. Finally, we measured the Sr2+ concentration by Atomic Adsorption Spectrometer (AAS) (Thermo, iCE3300). We compared the Sr2+concentration in the solution both prior to and then again after it was stirred. We analyzed the crystal structure and the morphology of both the shell and CaCO3. The crystal structure of the sample was examined by using X-ray Diffractometer (XRD)(Rigaku, SA-HF3). The surface morphology of samples were analyzed by Scanning Electron Microscope(SEM)(JEOL, JSM-6360A). Results and discussion We calculated the amount of substance from the concentration of solution measured by AAS. The amount of both the Sr2+ and the Ca2+ was plotted against the stirring time. In Fig.1, which is the solid line, we were able to observe a clear decrease in Sr2+ amount. In Fig.1, which is the dotted line, we witnessed a marked increase in Ca2+ amount. Both, the decreasing Sr2+ and increasing Ca2+, were directly related to the amount of time spent stirring. We assumed that Sr2+ substituted with Ca2+ of the CaCO3 which is the main component of the shell. We were then able to conclude that this is the reason why the amount of Sr2+ was reduced. According to the XRD pattern shown in Fig.2, it was clear that the scallop shell and CaCO3 have almost the same crystal structure. There are no differences between scallop shells and CaCO3 as far as crystal structure is concerned. The morphology of the inner surface of the shell is shown in Fig.3. A micro column structure of the scallop shell was observed on it. This structure is supposed to be an important factor for the adsorption of Sr2+.

Design and performance study of hybrid photocatalytic reactor-PVDF/MWCNT nanocomposite membrane system for treatment of petroleum refinery wastewater

This study focuses on the design and performance of a hybrid system consisting of a photocatalytic reactor and a membrane permeation cell. Initially, an ultraviolet lamp was installed in the photocatalytic reactor to decompose the organic pollutants in the presence of 200ppm titanium-dioxide (TiO2). Individual hydrocarbon pollutants were identified by gas chromatography–mass spectrometry (GC–MS) analysis of wastewater samples. Polyvinylidene fluoride (PVDF)/multi-walled carbon nanotube (MWCNT) nanocomposite membranes were fabricated to enhance the rejection, flux and fouling resistance for full filtration of pollutants from photocatalytic reactor such as decomposed refinery wastewater and TiO2 photocatalyst. The nanocomposite membranes were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TiO2 cross-over during permeation was detected by using an atomic adsorption spectrometer, which proved that TiO2 rejection was more than 99% for oxidized MWCNT nanocomposite membranes. Furthermore, GC–MS analysis was concluded over 90% decomposition which occurred by photocatalytic reaction and practically all pollutants were removed by ultrafiltration permeation cell. The nanocomposite membrane with 1.0wt.% of oxidized MWCNTs incorporated in PVDF matrix was found to be the best nanocomposite membrane among all of the fabricated membranes for the filtration purposes, due to the over 99% rejection and excellent anti-fouling property.

Mercury and selenium intake by seafood from the Ionian Sea: A risk evaluation

The subject of the present study is the evaluation of the concentrations of mercury (Hg) and selenium (Se) in fish and shellfish from the Gulf of Catania (Ionian Sea) and the assessment of related risk-based consumption limits per single contaminant in adults and children. In contrast to the potential harm from Hg, Se is an essential element that is normally found in high levels in seafood. If the amount of Hg is high enough, it could bind Se and irreversibly inhibit selenium-dependent enzymes. Thus, adequate levels of Se need to be available to replace the amount of Se lost to Hg sequestration, thereby maintaining normal selenoprotein synthesis. Hg analysis was conducted using a flow injection analysis system coupled with an atomic adsorption spectrometer, and Se analysis was conducted using an inductively coupled plasma mass spectrometry (ICP-MS). Of the trace elements investigated, only Hg has a limit set by the European Community for human consumption, and this was never exceeded. Nevertheless, based on Target Hazard Quotient (THQ) over 1, and on the Estimated Daily Intake per meal (EDIm) higher than the Provisional Tolerable Intake (PTI) suggested by the Joint FAO/WHO Expert Committee on Food Additive (JECFA), Hg oral exposure derived from consumption of the benthonic fish and of the bigger pelagic fish species analyzed, could follow the occurrence of systemic effects. Se was found always in molar excess respect to Hg in all pelagic fish and in the shellfish, nearly equimolar in the benthonic fish. Determining the evidence that foods, such as pelagic fish, with high molar excess of Se, could contribute to replace the amount of Se bound to Hg and thereby maintaining normal selenoprotein synthesis, is useful for a better understanding of the seafood safety.

Electroplating sludge metal recovering with vitrification using mineral powder additive

Electroplating sludge is a potential secondary metal resource. In this study, vitrification process was employed to recover the metal from plating sludge, and the mineral powder additive was used to improve the recovery efficiency of vitrification process. Plating sludge was collected from an industrial Ni electroplating workshop in Taiwan. Mineral powder composed of dolomite, limestone, and cullet was employed as the reductant additive to improve the efficiency of producing metallic ingot in the vitrification process. The metals Al, Ca, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were analyzed with an atomic adsorption spectrometer (AAS). Ni, Fe, and Cr are potential candidates for recovery using the vitrification process due to their relatively high mass content. To determine the optimal efficiency, vitrification processes were performed with additive to sludge mass ratios of 5:5, 6:4, 7:3, 8:2, and 9:1. The results indicate that the optimal metal recovery efficiency of Ni, Fe, and Cr was achieved at an additive to sludge ratio of 8:2. In addition, the toxicity characteristic leaching procedure (TCLP) test results for the slag meet the Taiwan EPA's regulated level of Cr(VI), Cr, Pb, and Cu. To examine the changes in microstructure, the crystalline phases of slag were analyzed with XRD. The XRD patterns show that the appearance of pseudowollastonite improves the metal recovery efficiency, whereas the appearance of diopside and quartz decreased efficiency. The preliminary economic analysis indicated that the vitrification was not only a feasible but also a cost-effective technology for the electroplating sludge treatment in this study. However, the practical application should further depend on the building cost of the plant and financial support from the government.

Preparation of core–shell magnetic ion-imprinted polymer for selective extraction of Pb(II) from environmental samples

A novel magnetic ion-imprinted polymer (Fe 3O 4@SiO 2@IIP) was synthesized by using 3-(2-aminoethylamino)propyltrimethoxysilane (AAPTS) as the functional monomer, tetraethylorthosilicate (TEOS) as the cross-linker and Pb(II) as the template and evaluated for selective extraction of Pb(II) from environmental sample by magnetic solid phase extraction (M-SPE) procedure. The factors affecting separation and preconcentration of the target heavy metals involving pH, eluting solvent and sample volume were studied in detail. Under the optimized experimental conditions, the kinetics adsorption and adsorption capacity of the Fe 3O 4@SiO 2@IIP toward Pb(II) were estimated. The results indicated that the adsorption mechanism is corresponding with the second-order adsorption process with correlation coefficient ( r 2 = 0.990), and the maximum adsorption capacity is 19.61 mg g −1. The relative selectivity factor ( β) values of Pb(II)/Cu(II), Pb(II)/Zn(II), Pb(II)/Cd(II) and Pb(II)/Hg(II) are 7.41, 6.76, 3.75 and 6.39, respectively. The Fe 3O 4@SiO 2@IIP was applied for extracting and detecting of Pb(II) in real environmental samples combined with atomic adsorption spectrometer successfully with high recoveries of 98.0%.

Recovery of nickel from mixed solution containing light metals by PSt/MA resin

The construction procedure and structure of Ni 2+ macromolecular complexes with series of poly styrene and maleic anhydride (PSt/MA) were studied. Both the copolymers and the complexes (Ni-PSt/MA) were characterized by means of FTIR, elemental analysis, gel permeation chromatography (GPC) and atomic adsorption spectrometer (AAS). A further study using PSt/MA as chelating resin to recover Ni 2+ was performed. The adsorption behavior for Ni 2+ and various relating parameters of PSt/MA in the separation process were determined. The results indicate that the adsorption capability varies with pH values and the PSt/MA can recover Ni 2+ in higher adsorption rate and higher selective coefficient from a mixed solution containing light metals such as Ca 2+ and Mg 2+ impurities.

Degradation Characteristics of Elastomeric Gasket Materials in a Simulated PEM Fuel Cell Environment

Polymer electrolyte membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the reactant gases (hydrogen and oxygen) within their respective regions. The stability of the gaskets/seals is critical to the operating life as well as the electrochemical performance of the fuel cell. The time-dependant chemical and mechanical degradation of two commercially available silicones-based elastomeric gasket materials in a simulated fuel cell environment was investigated in this work. Two temperatures based on actual fuel cell operation were selected and used in this study. Using optical microscopy, the topographical damage on the sample surface due to the acidic environment was revealed. Atomic adsorption spectrometer analysis shows that silicon, calcium, and magnesium were leached from the materials into the soaking solution. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were employed to study the surface chemistry of the elastomeric gasket materials before and after exposure to the simulated fuel cell environment over time. The ATR-FTIR and XPS test results indicate that the surface chemistry changed significantly and the chemical degradation mechanism is de-crosslinking and chain scission in the backbone. The microindentation test results show that the mechanical properties of the silicone materials changed significantly after exposure to the simulated PEM fuel cell environment over time.