Papers by Keyword: Mercury

Abstract: On-site and portable detection of heavy metals, especially in water, is critical for public health safety. Mercury is a toxic heavy metal and poses environmental and health hazard concerns causing neurological and behavioral disorders. Metallic nanoparticles possess unique optical properties, which can be used for heavy metal sensing applications. In this study, a colorimetric method for detecting mercury using silver nanoparticles was developed. The reduction of Ag⁺ to AgNP was initiated using sunlight with coffee pulp aqueous extract as a reducing agent. The UV-Vis spectrum of the as-prepared AgNP solution shows a maximum absorption peak at 433 nm due to the metal’s localized surface plasmon resonance (LSPR). The SEM analysis of the dried sample shows an aggregate of AgNPs with spherical morphology with diameters less than 100 nm. The dynamic light scattering distribution curve shows a bimodal peak with a mean hydrodynamic radius of 12.73 nm and 145 nm, respectively. The large hydrodynamic radius of more than 100 nm may be attributed to the presence of AgNP aggregates in the solution. The synthesized AgNP was shown to selectively detect Hg²⁺ ions in solution colorimetrically. A linear calibration curve was obtained for the Hg²⁺ solution between 0.04 mM and 0.2 mM with R² equal to 0.9934. This proposed method can potentially be used in the analysis of actual water samples.

Abstract: This article aims to investigate the effectiveness of Sargassum in eliminating mercury in wastewater. The most toxic form of mercury is the methyl mercury, as 90% is absorbed in the body, and mercury chloride only by 2%. Current cleaning methods can be very expensive. Some adverse effects of methyl mercury include, mainly, damage to the brain and kidneys, but it can also cause nervous system disorders. The percentage of Mercury adsorbed by sargassum was analyzed, varying contact times, sargassum concentrations and particle size in microns. Several processes were used, as 4 kilos of sargassum were washed with detergent and water, dehydration techniques were applied to dry the product inside a drying oven, and pulverization was also implemented to obtain 1800 g in different particle sizes (from 100 microns to 300 microns) of product. Subsequently, solutions were prepared with concentrations of Mercury ranging from 10 to 100 ppb. To analyze the effectiveness of its adsorption, 2, 4 and 6 grams of sargassum were deposited in said solutions at contact times of 20, 40 and 60 minutes to finally calculate the decontamination rates of water by different formulas. The fatty acid profile was also analyzed for the adsorbent for a possibility of another property of sargassum.

Abstract: The Co-MoF was identified as better catalyst for colorimetric sensing for effective detection of Hg²⁺ ions. The mimicking activities and oxidise the TMB in the existence of hydrogen peroxide (H₂O₂) to create a blue-colored sample. The oxidation of TMB was greatly delayed or reduced in the existence of bio-molecule Glutathione since of its stronger cations to repair capability. GSH substrates are oxidised when Hg²⁺ is introduced because of the higher interaction of mercury ions for GSH's thiol groups. Hg²⁺ concentrations ranged from 1 to 50 nM, and it exhibits a LOD of 0.28 nM reached in this study. To our surprise, the proposed sensor technology for detecting mercury contamination from industrial wastewater shows great potential.

Abstract: The application of selenium and mercury and the raw materials for extracting selenium and mercury were introduced. The current separation and extraction processes of selenium and mercury were described in detail, including pyrometallurgy and hydrometallurgy process, in addition to oxygen pressure leaching method and complex acid leaching method.

Abstract: The removal of mercury from the waterbody remains a severe challenge in ensuring environmental safety due to its highly toxic and non-biodegradable properties. Adsorption is an evidently effective method for heavy metal removal in water. This research aims to study the mercury (II) ion adsorption behavior in aqueous solution onto extruded natural bentonite in monolithic structure, bentonite-based monolith (BBM) adsorbent. BBM was characterized by XRD, BET, and SEM, the results verify BBM could improve adsorption performance assumed on its structure. Adsorption efficiency, isotherm model, and adsorption kinetic were investigated. Experiments were performed in a lab-scale batch reactor with mercury solution concentration varied from 1 to 5 mg/L. The maximum adsorption efficiency discovered to be 63,9%. The experimental data fitted well to Langmuir isotherm (non-linear) and kinetic model pseudo first order (non-linear), revealing the maximum monolayer capacity (Q_o) of BBM to be 0,187 mg/g with Langmuir constants K_L and a_L are 0,215 L/g dan 1,151 L/mg respectively. These value confirms that BBM adsorbent encompasses tremendous potential for mercury (II) ion removal in a solution.

Abstract: The target vessel, which enclosing liquid mercury, for the pulsed spallation neutron source at the J-PARC is severely damaged by cavitation caused by proton beam-induce pressure waves in mercury. To mitigate the cavitation damage, we adopted a double-walled structure with a narrow channel for the mercury at the beam window of the target vessel. The narrow channel disturbs the growth of cavitation bubbles due to the pressure gradient. In addition, gas microbubbles are injected into the mercury to suppress the pressure waves. After finishing service operation, the front end of the target vessel was cut out to inspect the effect of those cavitation damage mitigation technologies on the interior surface. The damage depth of the cutout specimens for the original design type and double-walled target vessels were quantitatively investigated by the replica method. The results showed that the double-walled target facing mercury with gas microbubbles operate 1812 MWh for an average power of 434 kW is equivalent to the damage of original design target operated 1048 MWh for average power of 181 kW. The erosion depth due to cavitation in the narrow channel is clearly smaller than on the wall facing bubbly mercury.

Abstract: Mercury pollution through water causes several dangerous diseases. Various efforts have been made to reduce mercury pollution. One of them is by using sorbent. Many ways to improve absorption efficiency, one of which is using magnetic sorbents. This study focused on the effect of grain size and the concentration of Mn_0.25Fe_2.75O₄@SiO₂ core-shell on mercury absorption efficiency. The synthesis of Mn_0.25Fe_2.75O₄@SiO₂ with 6 and 8 mL of TEOS was carried out through coprecipitation and sol-gel methods. The characterization using XRD, VSM, and FTIR was conducted to determine grain size, properties, and material functional groups proving that SiO₂ was successfully covered on the Fe₃O₄ surface. The percentage of absorption was found by using the AAS instrument. Diffraction data confirmed the presence of Fe₃O₄ and the amorphous SiO₂ phase. According to the Rietveld analysis of all samples demonstrated the particle size of Mn_0.25Fe_2.75O₄ around 11-12 nm. The Mn_0.25Fe_2.75O₄ core had superparamagnetic properties for magnetic separation, and the SiO₂ shell could protect the core of being oxidized or dissolved under acid condition. FTIR results showed the sample had a functional group of the main components of Fe-O and SiO₂ at a wavenumber of 420-507 cm^-1 and 801 cm^-1 (stretching) and 1078 cm^-1 (bending), respectively. The results of the mercury absorption test indicated that the smaller the grain size and the higher the concentration of TEOS, the percentage of mercury uptake would increase. In addition, the absorption percentage increased with the duration of absorption time given.

Abstract: A new colorimetric optode has been developed for preconcentration and visual determination of mercury ions in fish products. This optode is based on the color reaction of copper diethyldithiocarbamate with Hg²⁺ in the body of polymethylmethacrylate matrix. The optode exhibited sensitivity through the change of color from brown to colorless, which could be easily detected by naked-eye or spectrophotometric method. The influence of acidity, contact time and interference of foreign metal ions has been studied. The optode revealed good linearity in the range of 20-360 μg·L^-1, with a limit of detection of 8 μg·L^-1 Hg²⁺ at pH 5.2 and response time of 10 min.

Abstract: The adsorption ability of powdered activated carbons (PAC) derived from palm kernel shell (PKS) was investigated. PAC was prepared by chemical activation method using ZnCl₂ as an activating agents. The adsorption studies of Hg(II) was carried out under control condition with constant pH, solution temperature (30 °C), treatment time (90 min) and absorbent dosage (2.0 g L^-1). It was revealed that PAC efficiently removed as much as 10 mg L^-1 of Hg(II) with the percentage of removal up to 97.7 %. Both Langmuir and Freundlich adsorption isotherms were used to explain the adsorption behavior. Freundlich model was found to be fitted well and favored multilayer adsorption. The kinetics data were fitted with pseudo-first order and pseudo-second order, and it was found to obeys the pseudo-second order kinetic order. Recent finding suggest that PKS has the potential to be a promising precursor for the production of activated carbon with the excellent adsorption capacity to remove Hg(II) from aqueous solution.

Abstract: Three isolates of Streptomyces variabilis (AB5, F and K1A) and one isolate of Streptomyces sp. (C2) were isolated of acidic cultures from mineral ores and concentrates from mines of the Peruvian highlands. The isolates were identified molecular and phenotypically and characterized by growth at different conditions as pH tolerance, temperature, and sodium chloride and heavy metals resistance. Streptomyces sp. (C2) was able to grow until 200 ppm of mercury and S. variabilis (AB5) grows in the presence of 100 ppm of mercury. The isolates AB5 and K1A of S. variabilis were able to grow only until 50 ppm of mercury.All strains were tested by their ability to induce germination of Lactuca sativa, Medicago sativa and Phaseolus vulgaris seeds exposed to different mercury concentrations. It was shown a significative improvement in L.sativa and P. vulgaris. In L. sativa exposed to 50 ppm of mercury, all strains were able to improve germination, root length and number of leaves. Without Streptomyces addition, they only growth until 10 ppm of mercury. Streptomyces sp. isolate had better results in germination, root length and number of leaves of L. sativa . The results found in this work indicate the potential of these isolates for restoration of soils polluted with mercury.