Free Heavy Metal Research Articles

A synergistic strategy for the removal and secondary utilization of Cu(II) organic complexes in wastewater for the efficient degradation of tetracycline

Heavy metals in industries such as electroplating plants and semiconductor industries usually exist in the form of heavy metal organic complexes, and the removal of heavy metal organic complexes is troubled by the difficulty of decomplexation as well as the complexity of the treatment process of the free heavy metal ions after decomplexation. In this study, we proposed a synergistic strategy for the removal and secondary utilization of Cu(II) organic complexes (Cu-EDTA) in wastewater through mixed pyrolysis of carbon nitride precursor and Cu-EDTA, and the resulted product was used for the efficient degradation of tetracycline (TC). The unique electronic structure of carbon nitride and abundant surface defects anchor Cu during pyrolysis, which effectively realizes the removal of Cu-EDTA from wastewater. In addition, the Cu and O co-doped carbon nitride (Cu/O-CN) catalyst constructed by this strategy was proved to be effective in peroxydisulfate activation TC degradation, with a removal efficiency of 91.5% in 20 min, a degradation rate of 0.1643 min−1, and a TOC removal efficiency of 53%. X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculation revealed Cu+ active center constructed by the strong metal support interaction between Cu and carbon nitride in Cu/O-CN and the 1O2 dominated nonradical degradation pathways of TC. This study demonstrated a synergistic strategy for the efficient removal and secondary utilization of Cu-EDTA in wastewater, providing new insights into the use of environmentally friendly and cost-effective methods for the removal and recovery of heavy metal organic complexes from wastewater.

Factors controlling the heavy metal ion activity in soil contaminated by microplastics with different mulch durations: Partial least squares path model

Film covers have been widely applied worldwide. However, the effects of long-term plastic film mulching use on heavy metal (HM) activity in soil remain unclear. This study focused on farmland in the upstream part of the Pearl River in China and collected 103 soil samples after 2, 5, and 15 years of plastic film mulching. The main environmental factors controlling microplastics (MPs), plasticizer phthalic acid esters (PAEs), HM pollution characteristics, and HM activity were analyzed. The results showed that Polyethylene (PE) and di(2-ethylhexyl) dicyclohexyl phthalate (DCHP) were the main MPs and PAEs, respectively. The abundance of MPs and the concentrations of free HM ions (Cd, Cu, and Ni) in the soil solution increased with increasing plastic film mulching duration. The Partial Least Squares Path Model (PLS-PM) indicated that after plastic film mulching, soil chemical properties (pH/amorphous Fe) and biological properties (Dissolved organic carbon/ Easily oxidizable carbon/Microbial biomass carbon) were the main controlling factors for free and complexed HM ions (Cd, Pb, Cu, and Ni). These results suggest that, after plastic film mulching, MPs indirectly regulate HM activity by altering soil properties. This study provides a new perspective for the management of MPs and HM activities in agricultural ecosystems.

Development of a Novel Sulfur Quantum Dots: Synthesis, 99mTc Radiolabeling, and Biodistribution.

Sulfur quantum dots (SQDs) as free heavy metal element quantum dots have promising applications in diagnosis and therapy; however, SQDs' in vivo biodistribution has not been studied. In the current study, SQDs were synthesized directly from cheap sublimated sulfur powder via a one-pot solvothermal method, and sucrose was used as a stabilizer to enhance stability and biocompatibility. The as-obtained SQDs with an average size of 4.6 nm exhibited great water dispersity, highly favorable quantum yield (21.5%), and uniformly spherical shape which were confirmed by UV-Vis, fluorescence spectrophotometer, TEM, and FESEM/EDX/PSA analyses. Moreover, the as-synthesized SQDs had very low cytotoxicity based on cancer (C26) and normal (L929) cell lines via MTT assay. And also, SQDs were radio-labeled directly by Technetium-99m (99mTc), which had good stability ranging from 86 to 99% in PBS and human serum. The SQDs' cell uptake on C26 and L929 cell lines demonstrated that cancer cells had more uptake than normal cells by increasing concentrations. Moreover, SQDs' in vivo biodistribution results displayed high kidney dose accumulation and rapid renal clearance, making them suitable for imaging and therapeutic applications.

Molecular insights into migration of heavy metal ion in calcium silicate hydrate (CSH) surface and intra-CSH (Ca/Si = 1.3)

In order to enhance the efficiency of heavy metal solidification/stabilization (s/s), unexplored atomic-scale interaction mechanisms between cement hydration products and metal ion are important. The atomic underlying mechanism of migration of heavy metals in the main cement hydration products, hydrated calcium silicate (CSH), is investigated under multifactor via molecular dynamics simulation. The multifactor combines: The adsorption at CSH surface determining the ratio of free ions to adsorbed ions; Heavy metals at CSH interlayer causes CSH particles swelling/shrinkage. The pore consisting of CSH will be wider/narrower, in turn acting on the migration of free heavy metal ion. Simulation shows that CSH bonding heavy metal (Cu/Zn/Pb) capacity depends on the ability of Ca exchanging with them as determined by hydration shell stability of heavy metals. Within interphase zone, part heavy metals form a stable chemisorption with silicon chains via metal-OCSH-Si connection and others form fragile physical adsorption near the outside interphase. Moreover, Pb ion swells the particles but Cu and Zn shrink them, making the multilevel pore structures denser/sparser. Different amounts of free ions due to different interaction with CSH migrates in sparser/denser pores, ultimately determining the solidification/stabilization efficiency.

Stabilization of Pb, Cd, and Zn in soil by modified-zeolite: Mechanisms and evaluation of effectiveness

As a type of soil stabilization material, zeolite has good cation exchange ability and synchronous stabilization potential for multiple active heavy metal cations in soil. However, natural zeolite contains relatively high amounts of impurities, and has a single heavy metal stabilization mechanism, which limits its capacity to stabilize heavy metals in soil. To develop a stabilization material that could efficiently stabilize several heavy metals simultaneously, in the present study, modified zeolite (MZEO) was prepared via NaCl pretreatment, chitosan modification, modified chitosan loading, and CaSiO3 modification to enable Pb, Cd, and Zn stabilization in soil. The aim of the present study was to explore zeolite modification technologies, reveal the stabilization mechanism of polymetallic contaminated soil and evaluate the stabilization effects of MZEO. According to the results, the modification treatment increased the cation exchange capacity of MZEO nearly 8-fold, the specific surface area 3.4-fold, and its internal pore structure was richer, with more adsorption sites. The appearance of a -NH2 absorption bands confirmed the loading of chitosan successfully, and the modification enhanced the heavy metal stabilization mechanism. Upon the addition of MZEO to Baiyin soil, the chemical morphologies of heavy metals changed, which reduced the weak acid extracted forms of Pb, Cd, and Zn in the soil by 21%, 10%, and 19%, respectively. The potential mechanisms of free heavy metal reduction were ion exchange with Na in MZEO, heavy metal mineral formation by Al replacement in the crystal lattice, and bonding with SiO32− formed by the hydrolysis of MZEO-loaded synaptic CaSiO3 particles, to form silicate precipitation. MZEO application minimized heavy metal leaching risk in the soil and heavy metal biological/plant accessibility, with potential economic benefits. MZEO has promising applications in polluted soil remediation.

Performance of Chlorella Vulgaris Exposed to Heavy Metal Mixtures: Linking Measured Endpoints and Mechanisms.

Microalgae growth inhibition assays are candidates for referent ecotoxicology as a fundamental part of the strategy to reduce the use of fish and other animal models in aquatic toxicology. In the present work, the performance of Chlorella vulgaris exposed to heavy metals following standardized growth and photosynthesis inhibition assays was assessed in two different scenarios: (1) dilutions of single heavy metals and (2) an artificial mixture of heavy metals at similar levels as those found in natural rivers. Chemical speciation of heavy metals was estimated with Visual MINTEQ software; free heavy metal ion concentrations were used as input data, together with microalgae growth and photosynthesis inhibition, to compare different effects and explain possible toxicity mechanisms. The final goal was to assess the suitability of the ecotoxicological test based on the growth and photosynthesis inhibition of microalgae cultures, supported by mathematic models for regulatory and decision-making purposes. The C. vulgaris algae growth inhibition test was more sensitive for As, Zn, and Pb exposure whereas the photosynthesis inhibition test was more sensitive for Cu and Ni exposure. The effects on growth and photosynthesis were not related. C. vulgaris evidenced the formation of mucilaginous aggregations at lower copper concentrations. We found that the toxicity of a given heavy metal is not only determined by its chemical speciation; other chemical compounds (as nutrient loads) and biological interactions play an important role in the final toxicity. Predictive mixture effect models tend to overestimate the effects of metal mixtures in C. vulgaris for both growth and photosynthesis inhibition tests. Growth and photosynthesis inhibition tests give complementary information, and both are a fast, cheap, and sensitive alternative to animal testing. More research is needed to solve the challenge of complex pollutant mixtures as they are present in natural environments, where microalgae-based assays can be suitable monitoring tools for pollution management and regulatory purposes.

Possibility of using modified fly ash and organic fertilizers for remediation of heavy-metal-contaminated soils

New modified fly ash is an excellent amendment for stabilising soil heavy metals. In this study, new modified fly ash and an organic fertilizer were employed for soil heavy metal remediation. The applications of the organic fertilizer to the soil can lead to buffering of the alkalinity of new modified fly ash. The results of mixture treatments were better than those of the application of only new modified fly ash for free heavy metal reduction. Among them, the treatment of 0.4% organic fertilizer and 4% new modified fly ash led to a reduction in the Mehlich-3 extractable cadmium (Cd), copper (Cu), and lead (Pb) of 49.0%, 53.5%, 67.83%, respectively, but the treatment of 4% new modified fly ash led to the reduction of 47.6%, 48.09%, and 62.73%, respectively. By the end of the experiment, the urease and alkaline phosphatase activities in the soil had considerably improved, and those activities in the soil treated with 0.4% organic fertilizer and 4% new modified fly ash increased by 2.21 and 3.2 times, respectively, compared with that in the control treatment soil. Similarly, organic matter and available N, P, and K considerably improved with the addition of the organic fertilizer. This study demonstrated the importance of the application of organic fertilizers and new modified fly ash mixture for the remediation of HM-contaminated soils and the improvement of soil quality.

Decontamination of heavy metal complexes by advanced oxidation processes: A review

Heavy metal complexes with high mobility are widely distributed in wastewater from modern industries, which are more stable and refractory than free heavy metal ions. Their removals from wastewater draw increasing attentions and various technologies have been developed, among which advanced oxidation processes (AOPs) are more effectively and promising. Progresses on five representative types of AOPs, including Fenton (like) oxidation, electrochemical oxidation, photocatalytic oxidation, ozonation and discharge plasma oxidation for heavy metal complexes degradation are summarized in this review. Their rationales, advantages, applications, challenges and prospects are introduced independently. Combinations among these AOPs, such as electrochemical Fenton oxidation and photoelectrocatalytic oxidation, are also comprehensively highlighted. Future efforts should be made to reduce acid requirement and scale up for practical applications of AOPs for heavy metal complex degradation efficiently and cost-effectively.

Preparation and application properties of sustainable gelatin/chitosan soil conditioner microspheres

Traditional soil conditioners can be used as drugs to regulate elements in soil due to overuse or pollution. There are some negative effects such as low efficiency, hard to degrade and harmful to the environment when they are used. Soil conditioners prepared from sustainable macromolecules can reduce or eliminate these negative effects. In this work, gelatin (GL), chitosan (CS), magnesium ammonium phosphate (MAP) and fulvic acid (FA) were combined and prepared into GL/CS/MAP-FA soil conditioner microspheres with core-shell structure through emulsion crosslinking method. Scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FT-IR) analysis results clarified the surface composition of the microspheres and revealed the good coating performance of GL/CS shell materials. The thermal stability of the microspheres was measured by thermogravimetric analysis (TGA). Water-retention, degradation and crop cultivation showed that these microspheres owned good biocompatibility, which can extend the water-retention time of the soil, settle free heavy metal ions and promote crop growth. The load of fertilizer in the microsphere can effectively prolong the release cycle and improve the utilization rate of fertilizer.

Effects of phenolic acids on free radical scavenging and heavy metal bioavailability in kandelia obovata under cadmium and zinc stress

Current mechanism studies in plant heavy metal tolerance do not consider the effects of different phenolic acids on the bioavailability of heavy metals and the comparison with antioxidant enzyme system in the hydroxyl radical scavenging capacity. In present study, by a set of pot culture experiments with adding cadmium (Cd) and zinc (Zn) to the sediments, the effects of different phenolic acids on the toxicity of Cd and Zn in Kandelia obovata and the dominant role in scavenging hydroxyl radicals were evaluated. The results showed that 100 mg kg−1 Zn treatment promoted the growth of plant under high concentrations of Cd and Zn stress. Under the stress of Cd and Zn, the phenolic acids were mainly metabolized by phenylpropanoid and flavonoid pathways, supplemented by shikimate and monolignol pathways in K. obovata. Eleven phenolic acids with different abilities of scavenging free radicals were detected in the plant, including pyrogallic acid (Gal), coumaric acid (Cou), protocatechuic acid (Pro), chlorogenic acid (Chl), 4-hydroxy benzoic acid (Hyd), caffeic acid (Caf), vanillic acid (Van), ferulic acid (Fer), benzoic acid (Ben), and salicylic acid (Sal). By adding phenolic acids to the sediments, chlorogenic acid (Chl), pyrogallic acid (Gal), cinnamic acid (Cin), and coumaric acid (Cou) behave as more reactive in changing Cd or Zn into residual fractions than the others, and chlorogenic acid (Chl), pyrogallic acid (Gal), ferulic acid (Fer) and caffeic acid (Caf) have higher ability of scavenging hydroxyl radicals than the others. In summary, K. obovata tends to synthesize phenolic acids with strong scavenging ability of free radicals and changing the bioavailability of Cd and Zn under high concentration of Cd and Zn stress. Phenolic acids played a crucial role in the mitigative effect of heavy metal stress via scavenging free radicals and involving in the process of Cd and Zn uptake and tolerance. The results will provide important theoretical basis and method guidance for mangrove wetland conservation.

FORMULATION AND EVALUATION OF STABILITY OF THAI PURPLE RICE BRAN-BASED COSMETIC PRODUCTS

Objective: The rice bran (RB) phytochemicals are known for several pharmacological properties. The current study aimed to extract the active principles from Thai purple rice bran, formulate the cosmetic products, evaluate the physical property, and stability of the products.Methods: The RB was prepared by 80% ethanolic extraction, and measured the total phenolic and anthocyanin content by HPLC, and spectrophotometric methods. The antioxidant capacity of RB oil (RBO), RB extract (RBE) was assessed by spectrophotometric methods. The cosmetic products were formulated with rice bran extract and fermented and distilled purple rice solution (FDPRS). The stability of the formulations was assessed. The heavy metal and microbial contamination were determined by atomic absorption spectrometry, and plating assay, respectively.Results: The yield of PRE and RBO was 0.92, and 1.62%, respectively. The total phenolic and anthocyanin content of PRE was 305.30 ± 6.15 mg gallic acid/g of extract, and 877.33 ± 87.73 mg cyanidin chloride /g of extract, respectively. RBO, PRE, and FDPRS exhibited high antioxidant capacity. The cosmetic formulations were physically stable in the heat-cool cycle, and the stability of active compounds was not affected while stored at 30°C for two months. The storage temperature affected the phenolic compounds present in the cosmetic formulations, especially at 45°C. There was no significant decrease in oryzanol content of soap formulation. All the formulations were free microbial and heavy metal contamination.Conclusion: The rice bran phytochemical based cosmetic products are rich in antioxidants, stable, free from heavy metals and microbial contaminations, and further fine tuning of the formulation may achieve the market quality.

FORMULATION AND EVALUATION OF STABILITY OF THAI PURPLE RICE BRAN-BASED COSMETIC PRODUCTS

Objective: The rice bran (RB) phytochemicals are known for several pharmacological properties. The current study aimed to extract the active principles from Thai purple rice bran, formulate the cosmetic products, evaluate the physical property, and stability of the products.Methods: The RB was prepared by 80% ethanolic extraction, and measured the total phenolic and anthocyanin content by HPLC, and spectrophotometric methods. The antioxidant capacity of RB oil (RBO), RB extract (RBE) was assessed by spectrophotometric methods. The cosmetic products were formulated with rice bran extract and fermented and distilled purple rice solution (FDPRS). The stability of the formulations was assessed. The heavy metal and microbial contamination were determined by atomic absorption spectrometry, and plating assay, respectively.Results: The yield of PRE and RBO was 0.92, and 1.62%, respectively. The total phenolic and anthocyanin content of PRE was 305.30 ± 6.15 mg gallic acid/g of extract, and 877.33 ± 87.73 mg cyanidin chloride /g of extract, respectively. RBO, PRE, and FDPRS exhibited high antioxidant capacity. The cosmetic formulations were physically stable in the heat-cool cycle, and the stability of active compounds was not affected while stored at 30°C for two months. The storage temperature affected the phenolic compounds present in the cosmetic formulations, especially at 45°C. There was no significant decrease in oryzanol content of soap formulation. All the formulations were free microbial and heavy metal contamination.Conclusion: The rice bran phytochemical based cosmetic products are rich in antioxidants, stable, free from heavy metals and microbial contaminations, and further fine tuning of the formulation may achieve the market quality.

Biosurfactants enhanced heavy metals removal from sludge in the electrokinetic treatment

High content of heavy metals in the sludge was the obstacle of sludge land application and resource recycling. In this work, rhamnolipid, saponin and sophorolipid were used to enhance heavy metals removal from the sludge in the electrokinetic tests. Also, the 0.1 mol L−1 HNO3 was used to control catholyte pH in the electrokinetic tests. The electric current with the duration time variation, sections pH and heavy metals residual concentrations with space and time variations were investigated in the electrokinetic tests. Results indicated that these three biosurfactants and catholyte conditioning (0.1 mol L−1 HNO3) could enhance heavy metals removal from sludge in the electrokinetic experiments. After EK experiments, Cu, Zn, Cr, Pb, Ni, Mn, Fe and Hg removal efficiencies in the enhanced EK experiment were higher than unenhanced EK experiment. Cu, Zn, Cr, Pb, Ni, Mn, Fe and Hg obtained an effective removal efficiency in the EK3 test, which were 55.8 ± 5.46%, 73.8 ± 6.23%, 64.0 ± 5.11%, 51.6 ± 5.32%, 60.8 ± 2.12%, 56.0 ± 3.21%, 41.0 ± 2.12%, 35.0 ± 2.12%, respectively. Heavy metals transferring toward the cathode were greater than anode, due to the free heavy metal ions and positively charged complexed heavy metal moved to the cathode chamber by electromigration. Rhamnolipid, saponin and sophorolipid can effectively enhance heavy metals removal from the sludge in the electrokinetic tests.

Performance of Raphidocelis subcapitata exposed to heavy metal mixtures

Microalgae growth inhibition assays are candidates for referent ecotoxicological assays, and are a fundamental part in the strategy to reduce the use of fish and other animal models in aquatic toxicology. In the present work, the performance of Raphidocelis subcapitata exposed to heavy metals following standardized growth inhibition assays has been assessed in three different scenarios: 1) dilutions of single heavy metals, 2) artificial mixture of heavy metals at similar levels than those found in natural rivers and, 3) natural samples containing known mixtures of contaminants (heavy metals). Chemical speciation of heavy metals has been estimated with Eh-pH diagram and Visual MINTEQ software; heavy metal and free heavy metal ion concentrations were used as input data, together with microalgae growth inhibition, for Dr. Fit software. The final goal was to assess the suitability of the ecotoxicological test based on the growth inhibition of microalgae cultures, and the mathematic models based on these results, for regulatory and decision-making purposes.The toxicity of a given heavy metal is not only determined by its chemical speciation; other chemical and biological interaction play an important role in the final toxicity. Raphidocelis subcapitata 48h-h-EC50 for tested heavy metals (especially Cu and Zn) were in agreement with previous studies, when ion metal bioavailability was assumed to be 100%. Nevertheless, the calculated growth inhibition was not in agreement with the obtained inhibition when exposed to the artificial mixture of heavy metals or the natural sample. Interactions between heavy metal ions and the compounds of the culture media and/or the natural sample determine heavy metal bioavailability, and eventually their toxicity.More research is needed for facing the challenge posed by pollutant mixtures as they are present in natural environments, and make microalgae-based assays suitable for pollution management and regulatory purposes.

Antibacterial, Antioxidant analysis of Phytochemical Extracts derived from seeds of Syzygium cumini L. against Pathogenic Bacteria

Syzygium cumini is a tropical fruit tree of great economic importance. The fruit is commonly known as jamun (Hindi), java plum, black plum, jambul and Indian blackberry. It is a large, evergreen widely distributed forest tree of India, Sri Lanka, Malaysia and Australia which is also cultivated for its edible fruits. The tree was introduced from India and tropical Asia to southern Africa for its edible and attractive fruits. S. cumini tree has proved to have medicinal properties against a number of diseases it has a high economic value for the application in the medicinal field its extract contain compound like flavonoids, alkaloids, glycosides, steroids, phenols, saponins, terpenoid, cardiac glycosides and tannins as the chemical class present in the extracts. In current research study, phytochemical extracts derived from seed of S. cumini for antimicrobial analysis and to explore its potential applications to develop green drug and as an alternative to antibiotics available to cure diseases without side effects. Phytochemical extracts were obtained by using water, methanol and acetone and various tests were performed to evaluate the presence of alkaloids and flavnoids with standard protocol; then biochemical characterization of these extracts were analyzed by using Fourier Transform Infrared (FT-IR) spectroscopy to evaluate the phytoconstiutents present in extracts. Then phytochemical extracts derived from seed extracts were examined for antimicrobial effects against various gram positive (Bacillus subtilis, Staphylococcus aureus, Bacillus cereus) and gram negative bacteria (Salmonella typhimurium, Salmonella enteric, E.coli) by disc diffusion method. After incubation period of 24 hrs at 370C zone of inhibition was measured and compared with standard antibiotic chloromphenicol and gentamycin. Antioxidant analysis was determined on the basis of the scavenging effect on the stable DPPH (2, 2-diphenyl-1-picrylhydrazyl) free radical activity and heavy metal absorption was also analyzed to detect the potential uses of these extracts as antioxidant. Methanolic extracts have shown more potent antimicrobial effects than water and acetone derived extracts. Terpenoids are well known for their antimicrobial, anti-inflammatory and anti-neoplastic activities, triterpenes and terpenoids have already been isolated. Saponins are reported to have antimicrobial, antiviral, antifungal, anti-inflammatory and haemolytic, hepatoprotective and anti- ulcer activities. Findings in current research studies can be implemented to develop green drug and nanoparticles for antimicrobial, anti-diabetic purposes and various immunomodulation studies to improve immunity of an individual.

Investigation of Anticorrosion Coatings for Iron Using Polyaniline By Electrochemical Impedance Method

<Introduction>The most efficient corrosion inhibitors are based on heavy metal such as Cr. However, the use of them has now been widely restricted by law due to environmental and toxicological issues. So recently, anticorrosion method with conducting polymer has attracted attention because of free heavy metal. The conducting polymer, polyaniline is known to have a number of molecular configurations by redox status and pH. Two half oxidized forms, protonated emerardine salt(ES) and deprotonated emerardine base(EB) change reversibly by acid-base processing. In order to investigate the anticorrosion mechanism of the iron plate coated by deprotonated polyaniline film, we investigate electrochemical characteristics by AC impedance technique in the different anion solutions. Moreover, native oxidation layer of bare iron is also investigated. The three models of the equivalent circuits are proposed to explain the anticorrosion mechanism of the iron plate coated by deprotonated polyaniline film. <Experiment>The metallic samples used in this study were bare iron JISG3141, rolled steel plate. All metallic samples were degreasing with acetone. EB was dissolved in N-methyl-2-pyrrolidinone and that 5.0 mg/mL polyaniline(EB) solution was prepared. This solution was casted to iron plate on the hot plate at 60 ° C. This state was maintaining for 6 hours to get EB coating plate. All AC impedance measurements were conducted using three-electrode system. Working electrode is iron electrode, reference electrode is saturated calomel electrode and counter electrode is Pt coil electrode. Also, two electrolysis solutions, 1.0 M NaCl solution and 0.1 M Na2B4O7 solution were used to compare corrosion behavior by anion species. [1] D. W. DeBerry, J.Electrochem.Soc., 132, 1022-1026(1985).

EFFECT OF DIFFERENT COOKING METHODS ON CHANGES OF FREE FATTY ACIDS, THIOBARBITORIC ACID, HEAVY METAL (NI, CR, CO, CD, PB) AND SENSORY PROPERTIES OF GRASS CARP (CTENOPHARYNGODONIDELLA)

Introduction: Grass carp (Ctenopharyngodonidella, family Cyprinidae) is one of the main fresh water fish species and highly demanded aquaculture species in Iran. Among the cultivated fish, grass carp, also called farmed white fish, has received great attention because of its similarity to Caspian white fish in Iran. The muscle of fish contains important levels of nutrients which are beneficial to health. Most research has been done and published on raw flesh. Cooking can lead to a loss of the nutritional value of foods. In this case the preservation of the maximum nutritive value can be ensured by using correct methods of cooking. The aim of this research was the influence of five cooking methods (poaching, boiling, microwave pan- frying and deep- frying) on changes of free fatty acids, thiobarbitoric acid, heavy metal (Ni, Cr, Co, Cd, Pb) and sensory properties of grass carp (Ctenopharyngodonidella)fillets was evaluated. Materials and method: Grass carpsamples were purchased from a local market in Khorramshahr city, Khuzestan province, Iran. The fish were kept alive and transported to thelaboratory. On arrival,tsamples were washed and eviscerated. The samples were filleted and cut into slices (100 g each). The fish samples were cooked using AOAC 976.16 procedure (method for cooking seafood). Five common cooking procedures were selected: poaching in stainless steel pot of boiling water for 30 min and 30 s, steaming in stainless steel steamer for 5 min and 30 s, microwaving in microwave for 40 s, pan-frying (without oil) in frying pan for 6 min at 180 oC and deep-frying in olive oil in a deep fryer for 5 min at 180 oC. After the cooking process, the samples were cooled to room temperature and the skin and backbone of the samples were removed. All fish in each lot were homogenized using a kitchen blender and analyzed to determine free fatty acid, thiobarbitoric acid, heavy metal and sensory properties. All sample homogenates were assayed in triplicate. Results and discussion: The results indicated that the cooking methods of pouching, microwave and deep-frying increased thiobarbitoric acid (TBA), while cooking methods of boiling and pan- frying did not change TBA. The free fatty acid (FFA) content of the fillets was significantly reduced by the different cooking methods. The Ni in the cooking methods of boiling, pan- frying and deep- frying was not detected. The Cr in the cooking method of deep-fried samples was significantly decreased. The Co concentrations were below limits of detection in all samples. The Cd was only detected in microwave samples. The Pb content increased during cooking of fillets. The results of sensory properties were showed that the texture, odour, flavor, colour and overall likeness properties improve likeness score to some extent in deep-frying method and there were not significantly different between boiling, poaching and pan-frying.

Construction of a self-luminescent cyanobacterial bioreporter that detects a broad range of bioavailable heavy metals in aquatic environments.

A self-luminescent bioreporter strain of the unicellular cyanobacterium Synechococcus sp. PCC 7942 was constructed by fusing the promoter region of the smt locus (encoding the transcriptional repressor SmtB and the metallothionein SmtA) to luxCDABE from Photorhabdus luminescens; the sensor smtB gene controlling the expression of smtA was cloned in the same vector. The bioreporter performance was tested with a range of heavy metals and was shown to respond linearly to divalent Zn, Cd, Cu, Co, Hg, and monovalent Ag. Chemical modeling was used to link bioreporter response with metal speciation and bioavailability. Limits of Detection (LODs), Maximum Permissive Concentrations (MPCs) and dynamic ranges for each metal were calculated in terms of free ion concentrations. The ranges of detection varied from 11 to 72 pM for Hg2+ (the ion to which the bioreporter was most sensitive) to 1.54–5.35 μM for Cd2+ with an order of decreasing sensitivity as follows: Hg2+ >> Cu2+ >> Ag+ > Co2+ ≥ Zn2+ > Cd2+. However, the maximum induction factor reached 75-fold in the case of Zn2+ and 56-fold in the case of Cd2+, implying that Zn2+ is the preferred metal in vivo for the SmtB sensor, followed by Cd2+, Ag+ and Cu2+ (around 45–50-fold induction), Hg2+ (30-fold) and finally Co2+ (20-fold). The bioreporter performance was tested in real environmental samples with different water matrix complexity artificially contaminated with increasing concentrations of Zn, Cd, Ag, and Cu, confirming its validity as a sensor of free heavy metal cations bioavailability in aquatic environments.

Synthesis, Spectral and Antioxidant Properties of Tin(II)-Rutin Complex

Rutin is one of the most common flavonoids present in nature that has a wide range of biological properties. A Tin(II)-rutin complex was synthesized from the raw material rutin and SnCl2 in an alkaline solution. The complex was characterized by UV-vis, IR, 1H NMR, and 13C NMR spectroscopy. We evaluated the free radical scavenging activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method, and the results showed that pure rutin was more effective than the Tin(II)-rutin complex in terms of antioxidant activity. Supplementing diet by foods rich in rutin and other flavonoids, such as vegetables and fruits, may contribute to removing free radicals and heavy metal ions in our body.

A novel synthesis, characterization and application of Fe and Co anionic metal complex azo dyes based on environmental considerations

The synthesis and characterization of a novel Fe-complex as a substitute for the Cr-complex and Co-complex acid azo dyes was carried out and the subsequent use of ultra-filtration was studied with the aim of purifying the metal complex dyes and thus increasing dye strength and solubility and additionally reducing the free heavy metal present in the final dye. A drastic reduction in the content of inorganic additives and free metal was achieved by the ultra-filtration process. The ultra-filtrated and non-ultra-filtrated dyes were used to dye wool and nylon fabric. Colour measurements and fastness properties were performed on the dyeings made on wool and nylon and compared with the Cr-complex dyeings thus examining the possibility of using successfully the Fe-complex dye as possible replacement of the Cr- and Co-complex dyes. The synthesis of the Fe-complex dye combined with the implementation of ultra-filtration technology results in producing a more environmentally friendly innovative dye with greatly improved purity and solubility.