Monitoring and statistical evaluation of heavy metals in airborne particulates in Cairo, Egypt

Airborne particulate material was monitored as total suspended particles and particulate matter less than 10 μm at selected sites in Cairo. The selected sites represent heavily industrial and industrial–residential areas of Cairo, Egypt. The filters were further analyzed for lead, cadmium, zinc and nickel using ion chromatography. The chosen method was modified to improve resolution and decrease the retention time. The data obtained were treated statistically using one-way analysis of variance and correlated with the anthropological and industrial activities of the sites. The concentrations of the heavy metals are studied in terms of particle size, time dependence, and safety.     

Adsorption of a few heavy metals on natural and modified kaolinite and montmorillonite: a review

The feasibility of using two important and common clay minerals, kaolinite and montmorillonite, as adsorbents for removal of toxic heavy metals has been reviewed. A good number of works have been reported where the modifications of these natural clays were done to carry the adsorption of metals from aqueous solutions. The modification was predominantly done by pillaring with various polyoxy cations of Zr4+, Al3+, Si4+, Ti4+, Fe3+, Cr3+or Ga3+, etc. Preparation of pillared clays with quaternary ammonium cations, namely, tetramethylammonium-, tetramethylphosphonium- and trimethyl-phenylammonium-, N'-didodecyl-N, N'-tetramethylethanediammonium, etc, are also common. Moreover, the acid treatment of clays often boosted their adsorption capacities. The adsorption of toxic metals, viz., As, Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni, Zn, etc., have been studied predominantly. Montmorillonite and its modified forms have much higher metal adsorption capacity compared to that of kaolinite as well as modified-kaolinite.     

Effects of heavy metals and oxalate on the zeta potential of magnetite

Zeta potential is a function of surface coverage by charged species at a given pH, and it is theoretically determined by the activity of the species in solution. The zeta potentials of particles occurring in soils, such as clay and iron oxide minerals, directly affect the efficiency of the electrokinetic soil remediation. In this study, zeta potential of natural magnetite was studied by conducting electrophoretic mobility measurements in single and binary solution systems. It was shown that adsorption of charged species of Co(2+), Ni(2+), Cu(2+), Zn(2+), Pb(2+), and Cd(2+) and precipitation of their hydroxides at the mineral surface are dominant processes in the charging of the surface in high alkaline suspensions. Taking Pb(2+) as an example, three different mechanisms were proposed for its effect on the surface charge: if pH<5, competitive adsorption with H(3)O(+); if 56, precipitation of heavy metal hydroxides prevails. Oxalate anion changed the associated surface charge by neutralizing surface positive charges by complexing with iron at the surface, and ultimately reversed the surface to a negative zeta potential. Therefore the adsorption ability of heavy metal ions ultimately changed in the presence of oxalate ion. The changes in the zeta potentials of the magnetite suspensions with solution pH before and after adsorption were utilized to estimate the adsorption ability of heavy metal ions. The mechanisms for heavy metals and oxalate adsorption on magnetite were discussed in the view of the experimental results and published data.     

Development and optimization of magnetic technologies based processes for removal of some toxic heavy metals

In the developing countries where the cost is often a decisive factor, extensive studies were undertaken to test the most effective factors on the preparation, optimization and validation of the magnetic particles (or, more accurately, magnetizable particles) for removal of heavy metals from wastewaters. The objective of the proposed work was focused to provide promising solid-phase materials, which, are relatively in expensive and combine high surface capacity with fast efficient treatment. Four various metal oxides including hydrous ferric oxide (HFO), hydrous stannic oxide (HSO) and mixed ferric/stannic oxide (HMO), were prepared by precipitation with ammonia from metal chloride solutions. Two mixed oxides were prepared with different Sn/Fe ratios of 50% and 20%. Optimal conditions for the activation of these particles and the subsequent mixing of various metals oxides are tested together with the utility of the method to get a new composite material with developed chemical characteristics over their individual metal oxides. Factors affecting the sorption behavior of the prepared samples in basic and acid media were elucidated. The magnetic treatment procedure using the mixed oxide (50%) enables the equilibration step to be carried out rapidly mainly due to ferric oxide during the magnetization process and efficiently due to high capacity of the stannic oxide. A key factor in achieving very high uptake percentage is the reduction of non-specific binding of various heavy metals to the solid phase support. This is usually achieved by increasing the ion exchange capability, in addition to their adsorption process.     

Magnetically Recoverable Catalysts: Catalysis in Synthesis of Polyhydroquinolines

Molecules that contain polyhydroquinoline structural scaffolds are N-containing heterocycles which are of great interest to organic chemists and biologists. Polyhydroquinoline structural scaffolds which are known as calcium channel blockers have emerged as one of the most important class of drugs used for the treatment of cardiovascular and Alzheimer's diseases. Besides, recovery and reusability of catalysts are important issues to be discussed in modern catalysis research especially in organic synthesis. The concept of magnetically recoverable catalysts has been rapidly developed in recent times. Magnetic separation is an efficient strategy for the rapid separation of catalysts from the reaction medium. Also, an alternative to time-, solvent-, and energy-consuming separation techniques. In this review, we focused on the fabrication, surface-modification and characterization of nanomagnetic materials and their application, as magnetically recoverable catalysts, in the synthesis of polyhydroquinoline structural scaffolds.     

Solution extraction of transition and post-transition heavy and precious metals by chelate and macrocyclic ligands

This review focuses on compounds and methods that can be used for the extraction and separation from solution of two classes of elements that we define as heavy metals and precious metals. These elements are often targeted because they are toxic, costly, and their coordination chemistry has already been well studied, and because there is a need to develop methods of economically extracting, separating and recovering them from waste sites. This review outlines possible strategies that can be used, and reviews the present literature regarding the available methods for their extraction.     

Preparation of core-shell magnetic Fe3O4@SiO2-dithiocarbamate nanoparticle and its application for the Ni2+, Cu2+ removal

A typical superparamagnetic nanoparticles-based dithiocarbamate absorbent (Fe₃O₄@SiO₂-DTC) with core-shell structure was applied for aqueous solution heavy metal ions Ni²⁺, Cu²⁺ removal.     

黄芪口服液中8种重金属元素含量的测定

在2015年版《中国药典》的基础上,采用原子荧光光谱法和电感耦合等离子体质谱法对黄芪口服液中的铅、砷、镉、汞、铜、锌、镍和铬进行测定,并对所用试剂、器皿,赶酸时间,内标的种类和加入方式进行了优化。结果表明,在样品处理前对器皿采用硝酸(30%)处理,赶酸时间在1.5h以上,以手动方式加入单内标103 Rh溶液,可以得到较准确、稳定的测定结果,8种元素测定的相对标准偏差(RSD)均小于4%,Hg、As、Cu、Pb、Zn、Cd、Ni、Cr的检出限分别为0.089、0.21、0.45、0.15、0.45、0.025、0.35和0.39μg/L,8种元素的加标回收率在92.0%～114%。方法对于黄芪口服液中痕量元素的检测,结果稳定,过程简单,引入污染小。     

ICP-MS determination of heavy metals in submerged cultures of wood-rotting fungi

Accumulation of five heavy metal ions by five species of wood-rotting basidiomycetes during a 9-day cultivation was studied. Contents of Cd, Cu, Pb, and Zn were measured using ICP-MS; the amount of mercury was determined directly in solid samples using the Advanced Mercury Analyser. A standard operation procedure for the sample preparation and determination of metal content was developed and validated. Presence of Cd, Cu, Hg, and Pb decreased the accumulation of zinc by the fungi. The basidiomycete Pycnoporus cinnabarinus exhibited the highest metal binding capacity of all fungi tested.     

Spectrafluorimetric method for the rapid screening of toxic heavy metals in water samples

A fast and inexpensive sensitive screening test for recognising potential wastewater contamination by the presence of highly toxic heavy metals is described. The test is based on the reaction of the toxic heavy metals Hg(II), Cd(II), Pb(II) and Ag(I) with 6-mercaptopurine (6-MP) to produce highly fluorescent complexes.Optimum experimental conditions include a buffer of pH 7.2 (0.1 M citric acid/0.2 M Na₂HPO₄), a chelating reagent concentration of 6×10⁻⁴ M and the addition of 10⁻⁴ M of o-phenanthroline. The fluorescence emitted by the complexes was measured at 380 and 540 nm for excitation and emission wavelengths, respectively.Detection limits of 4, 3, 6 and 3 μg l⁻¹ were achieved for Hg, Cd, Pb and Ag. Relative standard deviation (R.S.D.) were between ±2 and ±6% of the fluorescence signals for five identical samples. Potential interference effects from other heavy metals (Zn, Mn, Co, Fe, Ni and Cu), which could affect the response of the proposed screening test was investigated. Results showed that none of these metals give rise to noticeable fluorescence signals under the above described experimental conditions.Finally, the capability of the proposed heavy metal screening test for the analysis of contaminated water samples is discussed.     

Polyethylene glycol functionalized Fe3O4@MIL-101(Cr) for the efficient removal of heavy metals from Ligusticum chuanxiong Hort

In recent years, the quality and safety issues of Chinese medicinal herbs have received great attention worldwide. Thereinto, heavy metal contamination has been one of the most serious concerns. Compared to the wide research in the analysis of heavy metals in medicinal herbs, the studies on the removal of heavy metals are relatively limited. In this study, polyethylene glycol functionalized Fe₃O₄@MIL-101(Cr) (Fe₃O₄@MIL-101(Cr)@PEG) was designed and synthesized to remove heavy metals from the decoction of Ligusticum chuanxiong Hort. The in-house fabricated Fe₃O₄@MIL-101(Cr)@PEG was characterized by a porous structure and a large specific surface area. Then, the efficiency of the material for the removal of five heavy metals was tested under optimal adsorption conditions. Meanwhile, the content of Senkyunolide A, Senkyunolide I, and Ferulic acid, the solid content, and the HPLC fingerprints similarity were used as the quality monitoring indicators of Ligusticum chuanxiong Hort decoction before and after the heavy metal removal. Results showed that the magnetic nanomaterial had excellent removal efficiency for As⁵⁺ (81.4 %), Cd²⁺ (88.19 %), and Pb²⁺ (83.79 %) and certain removal efficiency for Ni²⁺ (51.59 %) and Zn²⁺ (55.4 %) under the spiked concentration of 50 μg/mL. The content of Senkyunolide A, Senkyunolide I, and Ferulic acid were decreased by less than 8.00 % after the removal of heavy metals. Besides, the loss rate of solid content was only 0.18 %, and the fingerprints similarity was over 99.9 %. The results indicated that Fe₃O₄@MIL-101(Cr)@PEG could efficiently and selectively remove heavy metals from Ligusticum chuanxiong Hort without affecting its effective components. Due to the advantages of low-cost, simple manipulation, and good efficiency, the material can be recommended for heavy metals removal from the aqueous solutions of medicinal herbs, providing a new and promising application for the removal of exogenous contaminants in medicinal herbs.     

Synthesis of PS/RB-Cs and its use in the treatment of water polluted with heavy metals

Polystyrene waste are non-biodegradable materials that causes harm to the environment. Red brick waste resulting from demolition and reconstruction are an obstacle to its disposal. To solve this problem and meet modern sustainability standards, this study utilized polystyrene (PS) foam and red brick construction waste to prepare composite materials (PS/RB-Cs) as a new efficient adsorbent. The PS/RB-Cs composite as an adsorbent was characterized using a UV–Vis Spectrophotometer, Energy Dispersive X-ray Spectroscopy (EDX), Scanning Electron Microscope (SEM), and transmission electron microscopy (TEM), which showed a clear spectrum shift after using PS/RB-Cs as an adsorbent. The PS/RB-Cs was characterized by a porous structure with higher surface area and high stability. The efficiency of the PS/RB-Cs in treating water contaminated with heavy metals such as cobalt and nickel was verified under different initial concentrations, temperatures, doses, pH, and contact times. The experimental q_e values were consistent with the q_e calculated values and were approximately 8 mg/g. The adsorption isotherm models showed that the adsorption results fit the Langmuir, Freundlich and Flory-Huggins isotherm models and that the process was favorable. By applying pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models, the adsorption process was found to follow PSO. The findings of this research validated that the composite material that was prepared serves as a potent adsorbent for the treatment of water that has been polluted by heavy metals.     

Practical methodology for the solubility speciation analysis of ambient dust deposits for heavy metals: application to a 6-month measurement campaign

A robust and accurate method for the quantitative determination of the water-soluble and water-insoluble, Ni, Cd, Pb and Zn contents of deposited ambient dust is presented. The extraction of the soluble metal phase from deposited ambient dust has been validated using commercially available ambient dust certified reference material. Results from a 6 month measurement campaign, from July to December 2004, are presented. Quantitative analysis of the two fractions, of different aqueous solubility (referred to here as ‘solubility speciation analysis’), within deposited ambient dust is reported for the first time. Additionally, the two Bergerhoff dust deposit gauges used in parallel to acquire the dust deposit samples have shown good inter-sampler comparability. The measured total deposition fluxes compare well with those previously reported in urban and semi-rural locations around the UK.     

A layered magnetic iron/iron oxide nanoscavenger for the analytical enrichment of ng-L concentration levels of heavy metals from water

Magnetically driven separation techniques have received considerable attention in recent decade because of their great potential application. In this study, we investigate the application of an unmodified layered magnetic Fe/Fe₂O₃ nanoscavenger for the analytical enrichment and determination of sub-parts per billion concentrations of Cd(II), Pb(II), Ni(II), Cr(VI) and As(V) from water samples. The synthesized nanoscavenger was characterized by BET, TGA, XRD and IR and the parameters influencing the extraction and recovery of the preconcentration process were assessed by atomic absorption spectrometry. The possible mechanism of the enrichment of heavy metals on Fe/Fe₂O₃ was proposed, which involved the dominant adsorption and reduction. The nanoscale size offers large surface area and high reactivity of sorption and reduction reactions. The obtained limits of detection for the metals studied were in the range of 20–125 ng L⁻¹ and the applicability of the nanomaterial was verified using a real sample matrix. The method is environmentally friendly as only 15 mg of nanoscavenger are used, no organic solvent is required for the extraction and the experiment is performed without the need for filtration or preparation of packed preconcentration columns.     

Determination of heavy metals in soil, mushroom and plant samples by atomic absorption spectrometry

The concentrations of heavy metals in the soil, mushroom and plant samples collected from Tokat, Turkey have been determined by flame and graphite furnace atomic absorption spectrometry after dry ashing, wet ashing and microwave digestion. The study of sample preparation procedures showed that the microwave digestion method was the best. Good accuracy was assured by the analysis of standard reference materials. The relative standard deviations for all measured metal concentrations were lower than 10%. In all cases, quantitative analytical recoveries ranging from 95 to 103% were obtained. Metal accumulation factors were calculated for mushroom and plant samples. High ratio of plants to soil cadmium, zinc and copper concentrations indicate that these elements are accumulated by mushrooms. Results obtained are in agreement with data reported in the literature.     

Removal of some heavy metals and fungicides from aqueous solutions using nano-hydroxyapatite,nano-bentonite and nanocomposite

A batch adsorption experiments were carried out to study the role of nanoparticles and nanocomposite on removal of some heavy metals and fungicides from aqueous solution. Nano-Hydroxyapatite (n-HAP), Nano-Bentonite (n-Bo) and Bentonite-hydroxyapatite nanocomposite (B-HAP NC) evaluated for the removal of some heavy metals and fungicides. The nanoparticles and nanocomposite were characterized by TEM, SEM and AFM, X-ray powder diffraction (XRD) and BET surface area. The batch adsorption was done using nanoparticles with Pb²⁺ and Ni²⁺ as example of heavy metals with concentrations up to 25 mgL⁻¹. Also, the adsorption experiment was conducted using nano-particles (n-HAP, n-Bo and B-HAP NC) with fungicides Stop Feng and Eurozole with concentrations 20 to 200 μg L⁻¹. Langmuir and Freundlich isotherm equations were employed to study the adsorption. The adsorption kinetics were conducted metal ion (Pb²⁺ and Ni²⁺) with residence time. The results indicated the maximum adsorption capacity of Ni⁺² was occurred on (n-HAP). While that maximum adsorption capacity of Pb²⁺ was occurred on (B-HAP NC). The rate of Ni⁺² removal was found to be very rapid during the initial 60 min. The adsorption of Pb⁺² by the n-HAP and (B-HAP NC) was a slow increase with time, it did not bring any remarkable effect. Also, the efficiency of adsorbent compounds used to remove the residue of fungicides Stop Feng and Eurozole shown the highest removal rates obtained with used nano-hydroxyapatite followed by bentonite-hydroxyapatitenanocomposite and nano-bentonite, respectively. The current results are very useful in the treatment of wastewater and the removal of heavy metals and fungicides, consequently making them suitable for agricultural purposes.     

Microbiological analysis of seawater and sediments in urban shorelines: Occurrence of heavy metals resistance bacteria on Chennai beaches, Bay of Bengal

The present study aims to evaluate the microbial diversity of bacteria, fungi and other pathogenic microorganisms present in seawater and sediments from Chennai shoreline (southeast coast of India).Chennai beaches are heavily polluted with untreated sewage effluents; municipal sewage disposal and recreational activities. Seawater was heavily contaminated with coliforms, Vibrio and Pseudomonas compare to sediment microbial contamination. Isolated bacteria are mostly pathogenic microorganisms including Vibrio, Pseudomonas, Coliforms, Salmonella and Shigella. Another potential environmental threat noticed was heavy metal resistance of these pathogenic strains against 50 mM of Ni, Cr, Cu, Co, Pb and Hg. Statistical analyses revealed that the Chennai coast may cause health risk to the recreational users and fisher folk, ultimately warrants environmental quality management to control microbial contamination     

Evidence of tin and other anthropogenic metals in particulate matter in Lisbon, Portugal

Thermal and epithermal neutron activation analysis techniques were used to analyze 27 Teflon air filters which were exposed to ambient air in Lisbon, Portugal, in February 2007. Tin was detected which is strongly suggestive of an anthropogenic source. Arsenic, antimony and copper were shown to be highly correlated, which is also suggestive of anthropogenic pollution. Trace element analysis of short- and medium-lived isotopes was performed yielding concentration information of various elements. Analytical sensitivities were enhanced using a Compton suppression system. Enrichment factor analysis shows that arsenic, tin, zinc, copper and antimony are at elevated concentrations in the Lisbon atmosphere.     

微塑料介导重金属在陆生植物中迁移及生物效应的影响

随着地膜在现代化农业中的广泛应用,微塑料在土壤中的残留问题日益严重。环境中释放的微塑料可能会与先前存在的重金属相互作用,导致生物效应(生物积累/毒性),并对人类健康和农产品安全构成威胁。目前,大多数研究集中于单一影响因素在土壤系统中的暴露和转化分析,有关微塑料和共存金属对环境联合影响的相当有限。本文综述了微塑料与重金属来源、相互作用机理与影响因素的研究现状,阐述了陆生植物对二者联合污染的生理响应。此外,未来的研究还应重点探讨微塑料与重金属共同在植物上暴露的具体分子机制、通过食物链对人类健康的影响、与其他混合污染物联合作用及微塑料老化过程对重金属迁移动态变化过程的影响。     

Analysis of the role of various biochar in the remediation of heavy metals in contaminated water and its kinetics study

Biochar prepared from agricultural wastes has gained great attention as a cost-effective treatment for metal-contaminated water. In this study, the effectiveness of corn cob and sugarcane bagasse-derived biochar for metals (Pb, Ni, and Cu) removal from an aqueous medium was examined following their physical, chemical, and structural characterization. Batch sorption experiments were carried out by employing the Langmuir and Freundlich equations. The results indicated that separation factor (R_L) values lay in the range of 0 and 1 representing the productive adsorption. The optimum dosage for metal adsorption can be recommended as 30 g L^?1. The optimum adsorption conditions were found at 6.5 and 5.5 pH, 1.5 g adsorbent dose, and at 180 min equilibrium time, for both corn cob and sugarcane bagasse biochars. At pH 6.5, adsorption capacities of Pb, Ni, and Cu were found maximum i.e., 11.34, 15.71, and 11.96 mg kg^?1 for corn cob and 8.96, 15.46, and 12 mg kg^?1, for sugarcane bagasse biochars, respectively. The metal adsorption kinetics was analyzed via four different types of the pseudo-second-order kinetic model. Moreover, the corn cob biochar showed a more pronounced activity in the removal of metals compared to sugarcane bagasse biochar. Hence, it was concluded that corncob and sugarcane bagasse-derived biochars could be utilized as economical bio-adsorbents for the heavy metals removal from wastewater.