Metal Absorption Research Articles

Changes in the health of metal-contaminated soil before and after stabilization and solidification

Stabilization is popularly employed to remediate metal-contaminated soils. It involves the absorption and precipitation of heavy metals to reduce their solubility, movement characteristics, or risk and toxicity. This study aimed to conduct a soil health assessment to determine changes in the health of metal-contaminated soil before and after the application of five stabilizers (acid mine drainage sludge (AMDS), coal mine drainage sludge (CMDS), steel slag, lime, and cement). Soil health assessment, including three soil functions, namely soil productivity, soil stability, and soil biodiversity, evaluated the physical, chemical, and biological indicators (total 16 indicators). Soil health index (SHI) of soil function was calculated by multiplying each indicator score by the weighting factor of each indicator. Total SHI was obtained by summing the three soil-function SHI. Total SHI of the stabilized and test soils followed the order as control soil (1.90) > heavy metal-contaminated soil (1.55) > CMDS-stabilized soil (1.29) > steel slag-stabilized soil (1.29) > AMDS-stabilized soil (1.26) > cement-stabilized soil (0.74) > lime-stabilized soil (0.67). Total SHI of the initial heavy metal-contaminated soil was evaluated as ‘normal’, before the stabilizer was applied; however, most of the stabilized soils became ‘bad’ after application of the stabilizers. Furthermore, soils stabilized by cement and lime showed very poor soil health. The results implied that changes in physical and chemical soil properties occurred due to the disturbance caused by the mixing of stabilizers, and ions eluted from the stabilizers could deteriorate soil health further. The findings indicated that soil treated with stabilizers is not suitable for agricultural purposes. Overall, the study suggested that stabilized soil from metal-contaminated sites should be covered with clean soil or monitored for some time before deciding its future agricultural use.

Three Cu (II)-hydrazone complexes: synthesis, physicochemical characteristics, stability, thermal analysis, and investigation of metal and iodine absorption

A three Schiff bases; Lhy, Lme, and Lph, as well as their CuLhy, CuLme, and CuLph complexes, were synthesized, and their physicochemical properties were investigated. Vibrational spectra proposed that the hydrazone ligands reacted as neutral tridentate chelator with NNO chelating centers to the Cu(II) ion via azomethine-N, Isatin-carbonyl, and pyridine-N forming the general formulae [Cu(L)2]Cl2 nH2O, where L = neutral tridentate Isatin-hydrazone ligand (L = Lhy, (CuLhy); L = Lme, (CuLme); L = Lph, (CuLph)). TG/DTA analyses have shown that there is at least one water molecule in each of the complexes. The spectrophotometric method was used to calculate the stoichiometry and thermodynamic characteristics of the metal complexes. By using density functional theory (DFT) techniques, the 3D structure of the produced complexes was verified. Based on an investigation of the electronic structural configurations of the complexes, calculations verified the predicted structure and clarified the nature of the chemical reactivity. Cu(II) adsorption from aqueous solutions onto ligands was investigated in a number of different settings. The influence of the initial metal concentration (10–100 ppm), the weight of the hydrazone ligands (0.1–1.0 gm), and the contact period (1–2 h) were all investigated as potential moderators of the uptake behavior. In just three hours, equilibrium had been reached thanks to the speedy adsorption process. An initial pH of ≈ 6–8 with a metal ion concentration of 80 ppm was found to be optimal. Iodine (I2) uptake behavior of hydrazone ligands was also studied using spectroscopy. In the first 8 h, hydrazone ligands exhibited high adsorption efficiency (E, %), which gradually declined until equilibrium was achieved after 25 h.Graphical abstract

Recent Progress in Low Threshold Plasmonic Nanolasers

AbstractPlasmonic nanolasers as a new class of coherent laser beyond the diffraction limit have attracted a lot of attention. However, the ultrahigh optical confinement caused by the plasmon effect is inevitably accompanied by metal absorption loss, thus increasing the pump threshold of the plasmonic nanolaser. In the past decade, many good results about low threshold plasmonic nanolasers have been realized and successfully extended to various applications. Here, this advance is discussed and some opinions are offered. First, based on the theoretical model and key parameters of the plasmonic nanolaser, the factors affecting the threshold are analyzed. Subsequently, the experimental efforts on the realization of low threshold plasmonic nanolasers from optical pumping to electrical pumping are reviewed. Their applications in on‐chip optical interconnects, biochemical analysis, and far‐field structure are then considered. Finally, feasible approaches to threshold reduction are discussed, as well as more possible applications in the future.

Laser light absorption and Brewster angle on liquid metal

Laser light absorption occurs in all laser-based processes and is, therefore, of importance for process simulation input, parameter optimization, and understanding of the occurring phenomena, such as melt pool flow or vaporization effects. Theoretical models were successful in predicting metal absorption for certain cases but often fail in high-temperature situations due to unknown impacts of occurring effects, such as surface irregularities or contaminations. Measuring absorption at high temperatures is challenging, and there are limited literature data available on values further above melting temperatures of metals. In this work, a radiometric measurement method is used to derive absorption values at high temperatures. The results show shifted values from Fresnel predictions and absorption peaks at comparably low incident angles. The decreasing absorption tendency at low incident angles was shown to be possibly induced by multi-interface absorption effects caused by surface layering and Knudsen layer effects. Surface layering was seen to be able to induce a very low Brewster angle comparable to the observations in the measurements and is, therefore, seen as a possible dominant factor in absorption at elevated temperatures.

Assessment of physicochemical properties of suspended sediment in Yangtze river estuary

ABSTRACT The physicochemical properties of suspended sediment affect the adsorption of heavy metals. Based on scanning electron microscopy-energy dispersive X-ray spectrometry and Image Pro Plus, we detected the physicochemical properties of suspended sediment in Yangtze Estuary. The following results were observed: (1) The graphical diameter (GD), roundness (RO) and fractal dimension (FD) of suspended sediment all presented normal distribution. According to Kolmogorov-Smirnov (K-S) test, the RO of suspended sediment of the ShiDongkou station at sewage outlet was 1.31, which was significantly higher than that of other points. (2) According to the K-S test, there was no significant difference in elements among various points in the Yangtze River Estuary. (3) Compared to the chemical properties of suspended sediment, its physical characteristics had a greater impact on heavy metal absorption. The physical characteristics had the least impact on the Cu adsorption, while the chemical properties had the least impact on the Cr absorption. This study deepens the understanding of suspended sediment in the Yangtze Estuary and provides comprehensive data for the numerical simulation of suspended sediment dynamics.

Health Risk Assessment of Lead, Cadmium, and Arsenic in Leafy Vegetables in Tehran, Iran: the Concentration Data Study.

Absorption of heavy and toxic metals causes their accumulation in the edible parts of vegetables. Pollutants such as heavy metals have directly affected the health of society and contributed to emerging diseases in recent years. The current study aimed to detect heavy metals (Pb, Cd, As) in highly consumed leafy vegetables provided from the Tehran market. Four types of vegetables, including dill, parsley, cress, and coriander were selected and 64 samples were randomly collected from fruit and vegetable markets in different regions of Tehran in August and September 2022. Then, samples were analyzed by the ICP-OES system, and health risk assessment was conducted using non-carcinogenic and carcinogenic approach. The range of Pb concentration was 54-314, < LOQ-289, < LOQ-230, and < LOQ-183μg/kg for dill, cress, parsley, and coriander, respectively. The high mean concentrations of Pb belong to the dill (161.43 ± 77.3μg/kg) and cress (154.75 ± 72.9μg/kg). In some samples of dill (37.5% of samples), cress (18.75% of samples), and parsley (12.5% of samples), the Pb content was above the national allowable limit (200μg/kg). The range of Cd concentration was < LOQ-42, < LOQ-41, < LOQ-30, and < LOQ-38μg/kg for dill, cress, parsley, and coriander, respectively. In none of the samples, the concentration of Cd was higher than the Iranian national limit (50μg/kg). The As occurrence was observed in all cress samples with a mean of 165.19 ± 64.83μg/kg. The range of As concentration was < LOQ-71, < LOQ-256, 58-273, and < LOQ-75μg/kg for parsley, dill, cress, and coriander, respectively. The THQ and HI values were higher than 1, and either ILCR value was higher than 10-4 for all tested heavy metals, it can be concluded that higher levels of heavy metals than the standard limits in some samples may raise the warning alarm and should come to the attention of the authorities.

Role of ionizing background on the statistics of metal absorbers in hydrodynamical simulations

ABSTRACT We study the statistical properties of O vi, C iv, and Ne viii absorbers at low-z (i.e. z &amp;lt; 0.5) using Sherwood simulations with ‘WIND’ only and ‘WIND + AGN’ feedback and massive black-II simulation that incorporates both ‘WIND’ i.e. outflows driven by stellar feedback and active galactic nucleus (AGN) feedbacks. For each simulation, by considering a wide range of metagalactic ionizing ultraviolet background (UVB), we show the statistical properties such as distribution functions of column density (N), b-parameter and velocity spread (ΔV90), the relationship between N and b-parameter, and the fraction of Ly α absorbers showing detectable metal lines as a function of N(H i) are influenced by the UVB used. This is because UVB changes the range in density, temperature, and metallicity of gas contributing to a given absorption line. For simulations considered here, we show the difference in some of the predicted distributions between different simulations is similar to the one obtained by varying the UVB for a given simulation. Most of the observed properties of O vi absorbers are roughly matched by Sherwood simulation with ‘WIND + AGN’ feedback when using the UVB with a lower O vi ionization rate. However, this simulation fails to produce observed distributions of C iv and fraction of H i absorbers with detectable metals. Therefore, in order to constrain different feedback processes and/or UVBs, using observed properties of H i and metal ions, it is important to perform simultaneous analysis of various observable parameters.

Carboxymethylated Gums and Derivatization: Strategies and Significance in Drug Delivery and Tissue Engineering.

Natural polysaccharides have been widely exploited in drug delivery and tissue engineering research. They exhibit excellent biocompatibility and fewer adverse effects; however, it is challenging to assess their bioactivities to that of manufactured synthetics because of their intrinsic physicochemical characteristics. Studies showed that the carboxymethylation of polysaccharides considerably increases the aqueous solubility and bioactivities of inherent polysaccharides and offers structural diversity, but it also has some limitations that can be resolved by derivatization or the grafting of carboxymethylated gums. The swelling ratio, flocculation capacity, viscosity, partition coefficient, metal absorption properties, and thermosensitivity of natural polysaccharides have been improved as a result of these changes. In order to create better and functionally enhanced polysaccharides, researchers have modified the structures and properties of carboxymethylated gums. This review summarizes the various ways of modifying carboxymethylated gums, explores the impact that molecular modifications have on their physicochemical characteristics and bioactivities, and sheds light on various applications for the derivatives of carboxymethylated polysaccharides.

Intrinsic optical absorption in Dirac metals

A Dirac metal is a doped (gated) Dirac material with the Fermi energy (EF) lying either in the conduction or valence bands. In the non-interacting picture, optical absorption in gapless Dirac metals occurs only if the frequency of incident photons (Ω) exceeds the direct (Pauli) frequency threshold, equal to 2EF. In this work, we study, both analytically and numerically, the role of electron–electron (ee) and electron–hole (eh) interactions in optical absorption of two-dimensional (2D) and three-dimensional (3D) Dirac metals in the entire interval of frequencies below 2EF. We show that, for Ω≪EF, the optical conductivity, ℜσ(Ω), arising from the combination of ee and certain eh scattering processes, scales as Ω2lnΩ in 2D and as Ω2 in 3D, respectively, both for short-range (Hubbard) and long-range (screened Coulomb) interactions. Another type of eh processes, similar to Auger–Meitner (AM) processes in atomic physics, starts to contribute for Ω above the direct threshold, equal to EF. Similar to the case of doped semiconductors with parabolic bands studied in prior literature, the AM contribution to ℜσ(Ω) in Dirac metals is manifested by a threshold singularity, ℜσ(Ω)∝(Ω−EF)d+2, where d is the spatial dimensionality and 0<Ω−EF≪EF. In contrast to doped semiconductors, however, the AM contribution in Dirac metals is completely overshadowed by the ee and other eh contributions. Numerically, ℜσ(Ω) happens to be small in almost the entire range of Ω<2EF. This finding may have important consequences for collective modes in Dirac metals lying below 2EF.

Identification of critical genes associated with lead exposure based on in silico analysis.

High blood levels of lead have been shown to relate to its toxicity, and its early detection in occupational workers is important to take necessary measures. The genes associated with lead toxicity were identified by in silico analysis of expression profile (GEO-GSE37567) based on lead exposure of peripheral blood mononuclear cells maintained in culture. The GEO2R tool was used to identify differentially expressed genes (DEGs) among three groups: control versus day-1 treatment, control versus day-2 treatment, and control versus day-1 treatment versus day-2 treatment, and their enrichment analysis was performed to categorize them for molecular function, biological process, cellular component, and KEGG pathways. The protein-protein interaction (PPI) network of DEGs was constructed using a STRING tool and hub genes were identified by using the CytoHubba plugin of Cytoscape. Top 250 DEGs were screened in the first and second groups and 211 DEGs were in the third group. Fifteen critical genes viz. MT1G, ASPH, MT1F, TMEM158, CDK5RAP2, BRCA2, MT1E, EDNRB, MT1H, KITLG, MT1X, MT2A, ARRDC4, MT1M, and MT1HL1 were selected for functional enrichment and pathway analysis. The DEGs were primarily enriched in metal ion binding, metal absorption, and cellular response to metal ions. The significantly enriched KEGG pathways included mineral absorption, melanogenesis, and cancer signaling pathways. PPI network analysis revealed that seven genes of the MT family exhibited good connectedness and served as a marker of lead induced toxicity. Our study suggests that MT1E, MT1H, MT1G, MT1X, MT1F, MT1M, and MT2A of the metallothioneins gene family may act as potential biomarkers to monitor lead exposure.

Microbial Melanin: Renewable Feedstock and Emerging Applications in Food-Related Systems

Melanin is among the most important natural pigments produced by various organisms, from microbes to plants and mammals. Melanins possess great properties such as radioprotective and antioxidant activity, heavy metal chelation and absorption of organic compounds. The biosynthesis of melanin through the DOPA metabolic pathway and/or the DHN pathway mainly involves the tyrosinase and laccase enzymes that catalyze the oxidation of phenolic and indolic substrates to form melanin classes, namely eumelanin, pheomelanin, allomelanins and pyomelanin. The cost-efficient production of melanin at a large scale, with a chemically specified composition, constitutes a major technical challenge. Alternative production routes including highly efficient microbial stains cultivated on renewable resources could sustain and up-scale melanin production capacity. The strategy of valorizing low-cost and abundant agro-industrial waste and byproduct streams complies with concepts of sustainable development and circular economy, thus eliminating the environmental footprint. Genetic engineering tools could substantially contribute to enhancing melanogenesis in natural producers via target gene overexpression and the recombination of novel strains. The production of biobased films for food packaging applications reinforced with melanin nanoparticles constitutes a market segment of high interest due to environmental and societal concerns around the end-of-life management of conventional plastics, gradual depletion of fossil resources, sustainability issues and high performance.

Observed dust surface density across cosmic times

ABSTRACT Our ability to interpret observations of galaxies and trace their stellar, gas, and dust content over cosmic time critically relies on our understanding of how the dust abundance and properties vary with environment. Here, we compute the dust surface density across cosmic times to put novel constraints on simulations of the build-up of dust. We provide observational estimates of the dust surface density consistently measured through depletion methods across a wide range of environments, going from the Milky Way up to z = 5.5 galaxies. These conservative measurements provide complementary estimates to extinction-based observations. In addition, we introduce the dust surface density distribution function – in analogy with the cold gas column density distribution functions. We fit a power law of the form log f(ΣDust) = −1.92 × log ΣDust − 3.65, which proves slightly steeper than that for neutral gas and metal absorbers. This observed relation, which can be computed by simulations predicting resolved dust mass functions through 2D projection, provides new constraints on modern dust models.

CORAL: Model of Ecological Impact of Heavy Metals on Soils via the Study of Modification of Concentration of Biomolecules in Earthworms (Eisenia fetida).

The traditional application for quantitative structure-property/activity relationships (QSPRs/QSARs) in the fields of thermodynamics, toxicology or drug design is predicting the impact of molecular features using data on the measurable characteristics of substances. However, it is often necessary to evaluate the influence of various exposure conditions and environmental factors, besides the molecular structure. Different enzyme-driven processes lead to the accumulation of metal ions by the worms. Heavy metals are sequestered in these organisms without being released back into the soil. In this study, we propose a novel approach for modeling the absorption of heavy metals, such as mercury and cobalt by worms. The models are based on optimal descriptors calculated for the so-called quasi-SMILES, which incorporate strings of codes reflecting experimental conditions. We modeled the impact on the levels of proteins, hydrocarbons, and lipids in an earthworm's body caused by different combinations of concentrations of heavy metals and exposure time observed over two months of exposure with a measurement interval of 15days.

Temperature annealing dependence of structural, magnetic, and antibacterial properties of silver substituted cobalt ferrite nanoparticles produced by coprecipitation route

In this study, silver-substituted cobalt ferrite (Ag0.02Co0.98Fe2O4) nanoparticles were successfully sensitized by the coprecipitation method. Annealing temperature treatment was used to modify the physical properties, i.e., 200 °C, 300 °C, 400 °C, and 500 °C. XRD analysis showed an increase in the annealing temperature, the crystallite size increased from 19.78 to 24.11 nm, and the grain size increased from 54.75 to 61.39 nm. The FTIR spectrum showed two prominent absorption bands around k ∼577 and k ∼381 cm−1, allowing metal oxide absorption in the tetrahedral and octahedral sites. There is a redistribution of cations which is more significant at the tetrahedral sites than at octahedral sites, toward a perfect spinel structure. An increased annealing temperature increased the saturation magnetization and coercive field from 31.80 to 50.60 emu g−1 and 651 to 1,077 Oe, respectively, attributable to an increase in the magnetocrystalline anisotropy constant. The evaluation of S. aureus and E. coli showed that Ag0.02Co0.98Fe2O4 indicated the zone of inhibition (ZOI) around the disks due to its antibacterial properties. The most significant on S.aureus and E.coli were 12.73 mm (mortality of 88%) and 12.43 mm (mortality of 80%), respectively, for Ag0.02Co0.98Fe2O4 annealed at 200 °C that have the minor grain size materials.

Photometric and Spectroscopic Observations of GRB 190106A: Emission from Reverse and Forward Shocks with Late-time Energy Injection

Early optical observations of gamma-ray bursts can significantly contribute to the study of the central engine and physical processes therein. However, of the thousands observed so far, only a few have data at optical wavelengths in the first minutes after the onset of the prompt emission. Here we report on GRB 190106A, whose afterglow was observed in optical bands just 36 s after the Swift/BAT trigger, i.e., during the prompt emission phase. The early optical afterglow exhibits a bimodal structure followed by a normal decay, with a faster decay after ∼T 0 + 1 day. We present optical photometric and spectroscopic observations of GRB 190106A. We derive the redshift via metal absorption lines from Xinglong 2.16 m/BFOSC spectroscopic observations. From the BFOSC spectrum, we measure z = 1.861 ± 0.002. The double-peak optical light curve is a significant feature predicted by the reverse-forward external-shock model. The shallow decay followed by a normal decay in both the X-ray and optical light curves is well explained with the standard forward-shock model with late-time energy injection. Therefore, GRB 190106A offers a case study for GRB emission from both reverse and forward shocks.

Upgrading the performance of a solar air collector with flexible aluminum air ducts and graphene nanoplatelet-enhanced absorber coating

Solar air collectors (SAC) have had great importance nowadays as far as clean energy production is concerned. In this study, the novel double flow solar air collectors were designed and their performance was investigated. This study aims to illustrate how affect the thermal performance and sustainability indicators of a newly-designed solar air heater with nano-enhanced aluminum air ducts instead of conventional sheet metal absorber plate. Two double flow solar air collectors, the former of which includes flexible aluminum air ducts coated by black matte paint (DSAC/FAD), whereas the latter one includes sheet metal plate coated by black matte paint (DSAC) were studied under the same environmental conditions. Moreover, the effect of nanoparticles on performance was investigated by adding nanoparticles into the paint. For this purpose, a set of experiments were simultaneously performed utilizing solar air collector with flexible aluminum air ducts coated with black matte paint (DSAC/FAD) and the double flow solar air collector with flexible aluminum air ducts coated with graphene nanoplatelet-included black matte paint (DSAC/NFAD). The experiments were conducted with the same fans of 40 W power. The energy, exergy and such sustainability indicators as waste exergy ratio (WER) and sustainability index (SI) were examined for each design. In the second part of experiments, the maximum thermal efficiency was obtained as 73.94% for the (DSAC/NFAD). The COP values for DSAC (Day 1), DSAC/FAD (Day 1), DSAC/FAD (Day 2), and DSAC/NFAD (Day 2) were found as 4.82, 4.52, 4.56, and 5.22, respectively. Similarly, the mean exergy efficiency of the (DSAC/NFAD) was calculated as 37.73%, whilst DSAC had the mean exergy rate of 17.93%. For the sustainability indicators, the best results of WER and SI were achieved in the experiments conducted on DSAC/NFAD. It was concluded that the double flow solar air collector with flexible aluminum air ducts can be utilized for thermal performance enhancement. Moreover, it is predicted that the outcomes of this study enlightened the new research topics to be emerged.

Evaluation of health risk and heavy metal pollution status in the Bhima River water Kalaburagi, Karnataka, India

The current investigation aimed to examine the present status of pollution in the Bhima River using indices (degree of contamination, heavy metal evaluation index, &amp; heavy metal pollution index) and health risk assessment (non-carcinogenic &amp; carcinogenic) by choosing some heavy metals like copper (Cu), chromium (Cr), manganese (Mn), cadmium (Cd), nickel (Ni), lead (Pb), &amp; zinc (Zn). Eight samples of surface water were collected monthly from October 2021 to September 2022 and analyzed by an atomic absorption spectrometer. The absorptions of heavy metals into sequence Mn &gt; Zn &gt; Cu &gt; Pb &gt; Ni &gt; Cr &gt; Cd have been observed. Pb, Cd, and Ni concentrations were considerably higher in samples collected near sewage runoff and along bridges. The calculated pollution indices indicate that five of the eight sampling sites are extremely polluted. Carcinogenic &amp; Non-carcinogenic dangers were tabulated for adults, children, &amp; infants according to the quantity of heavy metal content in an average daily consumption of water. For adults, children, as well as infants, the estimated non-carcinogenic standards were 3, 5, and 2, respectively. The computed carcinogenic risk levels for Pb, Cd, and Ni exceed the 10-6-10-4 acceptable limit. Indices and risk assessment values suggest that river water is not acceptable for ingestion by all age groups. Additionally, principal component analysis and cluster analysis disclosed that agricultural runoff, lead battery usage, sewage sludge, and bridge construction were the foremost sources of water quality degradation in the study zone. The development of a public drinking water supply is advised by this research to lessen negative impacts of heavy metal poisoning upon human health. Before making the water available for use by the public, it needs also be treated.

Assessment of trace metal bioaccumulation on the shells of edible gastropod Chicoreus ramosus and Hemifusus pugilinus

The current study aimed to examine how some gastropods absorbed trace metals (Chicoreus ramosus and Hemifusus pugilinus). The existence of 17 elements, including aluminium, arsenic, boron, calcium, cadmium, cobalt, chromium, copper, iron, potassium, lithium, manganese, sodium, nickel, phosphorus, lead, and zinc (Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Na, Ni, P, Pb, and Zn), was confirmed by inductively coupled plasma-mass spectroscopy (ICP-MS) analysis of trace metals. According to the ICP-MS results, C. ramosus (Al: 1.97 ± 0.2µg/g, Fe: 1.93 ± 0.2µg/g, and As: 1.52 ± 0.4µg/g) and H. pugilinus (Al: 1.85 ± 0.7µg/g, Fe: 1.68 ± 0.6µg/g, and As: 1.37 ± 0.6µg/g) both had significant amounts of aluminium, iron, and arsenic, respectively. Zinc concentrations of 0.58 to 0.7μg/g (C. ramosus) and 0.67 to 0.2μg/g were recorded (H. pugilinus). The elemental composition of the surface of the sample was confirmed by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) micrographs, which also showed the degree of trace metal absorption in the chosen gastropod species.

Isotermal Adsorpsi Ion Tembaga (II) Menggunakan Arang Tongkol Jagung (Zea mays L.) Teraktivasi Kalium Permanganat

Corn cobs which generally only become waste can be processed into activated carbon and used for the absorption of heavy metals, such as copper(II) ions. This study aims to determine the morphology of corn cobs charcoal after activation, determine the isothermal adsorption model of copper (II) metal ions on corncob-activated carbon, and then determine the adsorption capacity of copper (II) metal ions on corncob-activated carbon. The morphology of the corncob-activated charcoal obtained was analyzed using Scanning Electron Microscopy (SEM). Isothermal adsorption of copper (II) ions was carried out with various concentrations of copper (II) ions of 5, 10, 20, 50, and 100 ppm. The results of the analysis using SEM showed that the surface shape of the corncob-activated charcoal is regular and has pores with a pore diameter obtained in the range between 1.08-1.26 m and 1.38-1.59 m. The mechanism of adsorption of copper (II) ions by corncob-activated charcoal using KMnO4, following the Freundlich isothermal model with a value of R2 0.9993 with an adsorption capacity of 51 x 10-4 mmol/L. The utilization of activated carbon from corn cobs that are activated by potassium permanganate is very effective for adsorbing copper metal ion pollutants through an adsorption mechanism on the surface of activated carbon.

The Impact of Heavy Metal Accumulation on Some Physiological Parameters in Silphium perfoliatum L. Plants Grown in Hydroponic Systems.

Heavy metals like cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), resulting from anthropogenic activities, are elements with high persistence in nature, being able to accumulate in soils, water, and plants with significant impact to human and animal health. This study investigates the phytoremediation capacity of Silphium perfoliatum L. as a specific heavy metal hyperaccumulator and the effects of Cu, Zn, Cd, and Pb on some physiological and biochemical indices by growing plants under floating hydroponic systems in nutrient solutions under the presence of heavy metals. One-year-old plants of S. perfoliatum grown for 20 days in Hoagland solution with the addition of (ppm) Cu-400, Zn-1200, Cd-20, Pb-400, and Cu+Zn+Cd+Pb (400/1200/20/400) were investigated with respect to the control. The level of phytoremediation, manifested by the ability of heavy metal absorption and accumulation, was assessed. In addition, the impact of stress on the proline content, photosynthetic pigments, and enzymatic activity, as being key components of metabolism, was determined. The obtained results revealed a good absorption and selective accumulation capacity of S. perfoliatum plants for the studied heavy metals. Therefore, Cu and Zn mainly accumulate in the stems, Cd in the roots and stems, while Pb mainly accumulates in the roots. The proline tended to increase under stress conditions, depending on the pollutant and its concentration, with higher values in leaves and stems under the associated stress of the four metals and individually for Pb and Cd. In addition, the enzymatic activity recorded different values depending on the plant organ, its type, and the metal concentration on its substrate. The obtained results indicate a strong correlation between the metal type, concentration, and the mechanisms of absorption/accumulation of S. perfoliatum species, as well as the specific reactions of metabolic response.