Divalent Heavy Metal Research Articles

Expression of metallothionein in dimethylhydrazine-induced colonic precancerous and cancerous model in rat.

Metallothionein (MT) is a small protein with a high affinity for divalent heavy metals and has a function in zinc homeostasis. The purpose of this study was to assess the MT mRNA gene expression as well as the MT protein content by immunohistochemistry and radioimmunoassay (RIA) in 1,2-dimethylhydrazine (DMH)-induced precancerous and cancerous colonic tissue in rats. Six-week-old rats were given subcutaneous injections of DMH twice a week for 3 months and sacrificed at 4 months (precancerous model) and 6 months (cancerous model). We determined MT mRNA expression by reverse transcription polymerase chain reaction and MT protein content by both immunohistochemical expression and cadmium-109 RIA. MT mRNA expression in the large intestine showed statistically significant decrease in the precancerous (P < 0.01) and the cancerous (P < 0.001) model as compared with controls. Immunohistochemical expression of MT showed statistically significant decrease (P < 0.05) in the colonic cancerous tissue. MT content in the large intestine showed statistically significant decrease in precancerous (P < 0.005) and cancerous (P < 0.001) model as compared with controls. This study suggests that a decrease in the colonic MT mRNA expression, MT protein expression, and content in DMH-induced colonic cancer model is associated with the development of preneoplastic lesions and further progression to carcinoma in the colon results in a greater reduction in the levels of each of these parameters.

Functional interdependence of divalent heavy metal ions, voltage-gated calcium channels and glutamatergic transmission in the central nervous system

Functional interdependence of divalent heavy metal ions, voltage-gated calcium channels and glutamatergic transmission in the central nervous system

Kinetic model for sorption of divalent heavy metal ions on low cost minerals

A mathematical model is proposed that could predict the kinetic parameters for adsorption of divalent heavy metal ions (lead, copper and zinc) onto low-cost adsorbents such as pyrophyllite and rock phosphate using experimental data. The experiments were conducted with the initial concentrations of metal ions ranging from 10mg/L to 100mg/L. The mathematical model is based on the application of the Redlich-Peterson isotherm to mass transfer across the film surrounding the adsorbent. The developed non-linear sorption kinetic (NSK) mathematical model was solved using numerical integration by the trapezoidal method in Microsoft Excel along with the SOLVER function to obtain the best simulated values of the Redlich-Peterson constants A, B, r, the order of reaction n, and the film transfer coefficient α. Dissolution followed by precipitation was found to be the most probable mechanism responsible for heavy metal ion uptake by rock phosphate, while for pyrophyllite physical adsorption was governing mechanism at low concentrations (<100mg/L). The values of parameters A, B, r and α lie in the ranges of 0.015-23.2, 0.00003-3.09, 0.072-1, and 0.000057-52.8 [(L/mg)(n−1)/min], respectively, under different experimental conditions.

Differential deployment of parthenolide and phenylpropanoids in feverfew plants subjected to divalent heavy metals and trans-cinnamic acid

Accumulation of defense metabolites is an adaptive response to heavy metals in plants. However, deployment of multiple classes of defense metabolites under cadmium (Cd) and copper (Cu) toxicity is not understood. Here, the responses of parthenolide and phenylpropanoids were examined. Quantification of parthenolide and phenylpropanoids, and the expression of parthenolide biosynthesis genes were performed in feverfew leaves. Photosynthetic and physiological analysis of feverfew seedling treated with Cd and Cu were used to confirm the relationship between concentration of heavy metals and secondary metabolites accumulation. In addition, we examined the role of trans-Cinnamic acid (CA) as a phenylalanine ammonia-lyase (PAL) inhibitor alone or together with different Cd and Cu concentrations on plant growth and metabolites accumulation. Application of different Cu concentrations alone was more phytotoxic than respective Cd concentrations alone in terms of plant growth, photosynthesis, and oxidative status; however, addition of CA improved these attributes compared with their respective treatments alone. The results also revealed the repressing parthenolide biosynthesis versus phenylpropanoids when plants treated with heavy metals, whereas CA treatment showed the inverse effect. This study provides valuable information into the response of feverfew plants to Cd or Cu alone or together with a PAL inhibitor by linking stress-related physiological responses to changes in metabolites.

Carboxymethyl cellulose fiber as a fast binding and biodegradable adsorbent of heavy metals

In this study, a fast kinetic sorbent, epichlorohydrin cross-linked carboxymethyl cellulose fiber (ECMCF), was developed by using a simple synthetic method. SEM images showed that the ECMCF has a thin fibrous shape (20–90 µm of diameter) with a rough and porous surface, which is beneficial for the purpose of sorption. Cadmium metal ion (Cd(II)) was chosen as a model divalent heavy metal and the sorption performance of ECMCF was evaluated by batch and column experiments. The result of pH edge revealed that pH 6.0 was the best condition for Cd(II) sorption. The maximum uptake of Cd(II) by ECMCF was 150.60 ± 10.47 mg/g, which was comparable and higher than previously reported sorbents. Batch kinetic study showed that the ECMCF had a fast binding rate of Cd(II) within 2 min. Even in the column study, the ECMCF had a better breakthrough curve than two typical commercial ion exchange resins, Amberlite IRC 86 and Amberlite IR 120H, which were used as comparative sorbents.

LB03.08

Objective: hSLC39A8 (human solute carrier family 39 member 8) encodes a transmembrane protein that co-transports divalent heavy metal cations, such as Cd2+, with elusive physiological role. Recent genome-wide association studies have identified a non-synonymous single nucleotide polymorphism rs13107325 to be associated with hypertension. To investigate the functional impact of rs13107325 resulting in an amino acid substitution from Ala to Thr (A391T) in SLC39A8 on Cd2+ transport and the downstream signalling pathways. Design and method: Intracellular Cd2+ uptake was measured in HEK293 cells overexpressing SLC39A8 (Measure-iTTM Pb and Cd assay kit), and in human umbilical vascular endothelial cells (HUVECs) of different genotypes. Cd2+- and genotype-dependence of ERK1/2 and NF-kB pathway's activation were investigated by immunoblotting and dual-luciferase reporter assay. Cytotoxicity was measured by the lactate dehydrogenase assay and MTS assay. Molecular dynamics simulations were performed to predict in silico the effect of A391T on the structure and dynamics of SLC39A8 by using Robetta, TMHMM and etc. Results: Overexpression of Ala variant in HEK293 resulted in higher Cd2+ uptake and higher cytotoxicity as compared with the Thr variant. This is associated with increased phosphorylation of ERK1 and NF-kB activation. Similar trends were observed in HUVECs with endogenous SLC39A8. Bioinformatics tools also suggested a conformational change of the α-helical structural transition (residual 390–392) in the Thr mutant, which potentially attenuates the protein function. Conclusions: Increased Cd2+ uptake by SLC39A8 Ala variant (blood pressure raising allele) is associated with higher cell death in human kidney and endothelial cells. Therefore its altered function due to rs13107325 may indicate a potential therapeutic target in hypertension.

Divalent heavy metals adsorption onto different types of EDTA-modified mesoporous materials: Effectiveness and complexation rate

The removal of heavy metals from contaminated water was investigated using three types of ordered mesoporous silica (KIT-6, SBA-15 and SBA-16). The materials were functionalized with 3-aminopropyltrimethoxy-silane and ethylenediaminetetraacetic acid (EDTA) via two steps post grafting methods. Then the modified adsorbents were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen (N2) adsorption-desorption analysis, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis. The ordering of the supports was not affected after modification. KIT-6 and SBA-15 were found to be more efficient than SBA-16 due to their structural characteristics. The adsorption experiments were then conducted under different experimental conditions, such as pH, contact time and initial metals concentrations. The kinetic adsorption data obtained for the divalent metals followed the pseudo-second-order model indicating chmisorption. The exchange velocity (k_w) of each metallic ion is the main factor controlling both the adsorption rate and the selectivity which were higher for Cu2+ and Pb2+ than for Ni2+ and Cd2+. The maximum adsorption capacities were calculated by Langmuir model and were highly dependent on the amount of immobilized EDTA.

Removal of Heavy Metal Ions from Water by Cross-Linked Potato Di-Starch Phosphate Polymer

Potato di-starch phosphate polymer was synthesized by cross-linking potato starch with phosphorus oxy-chloride in basic medium and was then dispersed (0.2-1%) in aqueous solutions of divalent heavy metal ions (Cu2+, Ni2+, Zn2+, and Pb2+), to investigate their removal efficiency by the starch and was found to increase with increase in the polymeric starch content and increase in the heavy metal ion concentration. The removal order was found to be Pb2+ (78.1%) > Cu2+ (58.5%) > Zn2+ (20.5%) > Ni2+ (17.3%) against the constant polymeric starch content. UV-Visible, Fluorescence, FT-IR, SEM, and CHN techniques were used for characterization of different complexes formed.

Adsorption of Divalent Heavy Metal Ions from Aqueous Solution by Citric Acid Modified Pine Sawdust

Removal of certain divalent heavy metal ions (Cu2+, Pb2+, and Cd2+) from aqueous solutions by citric acid modified pine sawdust (CA-PS) was investigated in this study. The contribution of the citric acid modification to the increase of adsorption capacity of metal ions is significant. In the mono-component system of Cu2+, the maximum adsorption capacity of CA-PS (0.253 mmol/g or 16.19 mg/g) is more than three times higher than that of B-PS (0.079 mmol/g or 5.06 mg/g). The adsorption kinetics and isotherm of the pretreated pine sawdust (B-PS) and CA-PS can be well elucidated with the pseudo-second order model and the Langmuir model, respectively. The competitive adsorption behavior of Cu2+, Cd2+, and Pb2+ in the binary systems (Cu2++Pb2+, Cu2++Cd2+, and Pb2++Cd2+) were studied, and the preference of adsorption onto CA-PS can be ordered as Pb2+ > Cu2+ > Cd2+. The results showed the possibility of utilizing natural bio-sorbent as cost-effective adsorbent alternative for heavy metal ions removal.

Di-ionizable p-tert-butylcalix[4]arene-1,2-crown-5 ligands in the cone conformation: effect of acidic side arm length for solvent extraction of divalent metal ions

Several new di-ionizable p-tert-butylcalix[4]arene-1,2-crown-5 compounds were prepared in the cone conformation. For comparison with reported ligands, the systematic structural variation was a change of the pendent acidic groups from two adjacent –OCH2CO2H or –OCH2C(O)NHSO2Z (with Z=–Me, –Ph, –C6H4–4-NO2, –CF3) units to two adjacent –O(CH2)4CO2H or –O(CH2)4C(O)NHSO2Z groups. Competitive solvent extractions of alkaline earth metal (AEMC) cations from aqueous solutions into chloroform by these ligands were performed. Also single species solvent extractions were conducted for the divalent heavy metal cations of Pb2+ and Hg2+. Comparison of the extraction data for the new ligands with those reported reveal that the ligands with shorter proton-ionizable side arms are more effective divalent metal ion extractants.

Regulation of metallothionein gene expression in response to benzo[a]pyrene exposure and bacterial challenge in marine cultured black porgy (Acanthopagrus schlegelii)

Metallothioneins (MTs) are normally considered to be sensitive indicators of heavy metal pollution, but it is less clear whether the MT gene can actively respond to other environmental stresses. In this study, an MT mRNA molecular sequence of 471 bp (full length) was identified in marine cultured black porgy (Acanthopagrus schlegelii), encoding 60 amino acids containing 20 cysteine residues. The MT sequence was highly homologous to that of other fish belonging to the MT superfamily type 1 family. The three dimensional structure of the deduced MT peptide was composed of two metal-binding domains capable of ligating divalent heavy metals. The MT mRNA transcripts were detected in the 11 tested tissues and the highest quantity was present in the liver. Stresses by two factors, benzo[a]pyrene (B[a]p) exposure and bacterial challenge, were evaluated on MT gene expression. The level of MT gene transcripts in the liver significantly declined 24 h post B[a]p exposure and the quantity was significantly correlated with the exposure time during a 24 h period. In contrast, MT gene expression in the liver was significantly increased 48 h post bacterial infection and the quantity was significantly correlated with the infection time during this period of 48 h. Our results indicated that MT gene expression in black porgy liver was sensitive to environmental stresses other than just the heavy metal pollution reported, suggesting that the development of a reliable biomarker for heavy metal pollution will be more complex than expected.

Molecular and biochemical properties of two P1B2-ATPases, CsHMA3 and CsHMA4, from cucumber.

P1B-ATPases (heavy metal ATPases, HMAs) constitute a multigenic subfamily of P-ATPases involved in the transport of monovalent and divalent heavy metals in plant cells. Here, we present the organization of genes encoding the HMA family in the cucumber genome and report the function and biochemical properties of two cucumber proteins homologous to the HMA2-4-like plant HMAs. Eight genes encoding putative P1B -ATPases were identified in the cucumber genome. Among them, CsHMA3 was predominantly expressed in roots and up-regulated by Pb, Zn and Cd excess, whereas the CsHMA4 transcript was most abundant in roots and flowers of cucumber plants, and elevated under Pb and Zn excess. Expression of CsHMA3 in Saccharomyces cerevisiae enhanced yeast tolerance to Cd and Pb, whereas CsHMA4 conferred increased resistance of yeast cells to Cd and Zn. Immunostaining with specific antibodies raised against cucumber proteins revealed tonoplast localization of CsHMA3 and plasma membrane localization of CsHMA4 in cucumber root cells. Kinetic studies of CsHMA3 and CsHMA4 in yeast membranes indicated differing heavy metal cation affinities of these two proteins. Altogether, the results suggest an important role of CsHMA3 and CsHMA4 in Cd and Pb detoxification and Zn homeostasis in cucumber cells.

Silk fibroin/nylon-6 blend nanofilter matrix for copper removal from aqueous solution

Heavy metal pollution has become a serious problem for living organisms. In this study, silk fibroin (SF)/ nylon-6 nanofiber matrices were formed by electrospinning and their surface was modified with calcium phosphate (CaP) crystals to increase the affinity of divalent heavy metals. The properties of matrices were evaluated as a filter matrix for copper adsorption from aqueous solution. Atten- uated total reflectance fourier transform infrared spectros- copy (ATR-FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray pho- toelectron spectroscopy (XPS), and alizarin red staining method were used for characterization. Adsorption studies were performed by batch and continuous system. The various parameters regarding adsorption process such as pH of solution, surface area, initial copper concentration, and flow rate were optimized. Toxicity values were assessed before and after the Cu(II) adsorption studies. The resultant SF/nylon-6 nanofiber matrices indicate an excellent fibrous structure without beads (fiber diameter at 250 ± 50 nm) and modified successfully with CaP crystals. Adsorption results showed that the removal efficiency of copper could reach 32 % by continuous flow system whereas 77 % by batch system. Acute toxicity bioassays using Vibrio fischeri showed that the toxicity decreased after continuous and batch flow systems. For desorption study, different concen- trations of various desorption solutions were used and the percentage of Cu(II) desorption was determined as 11 %, approximately.

TRPC1 is involved in Ca2+ influx and cytotoxicity following Pb2+ exposure in human embryonic kidney cells

Lead (Pb2+) is a divalent heavy metal ion which causes severe damage to almost all life forms and is therefore considered a notorious toxicant. Exposure to Pb2+ is associated with poor cognitive development in children at relatively low levels that previously were thought to be safe. The mechanism through which Pb2+ enters cells, however, is unclear. Previous studies have showed that Ca2+ release-activated Ca2+ protein 1 (Orai1), a component of store-operated Ca2+ channels (SOCs), contributes to Pb2+ cellular entry. Canonical transient receptor potential (TRPC1) channel 1 is a transient receptor potential (TRP) channel which is sometimes referred to as a SOC. The present study was designed to investigate the role of TRPC1 in Pb2+ entry and toxicity in human embryonic kidney cells (HEK293). Additionally, changes in intracellular Ca2+ concentration were determined through Fluo-4 and Mag-fluo-4 fluorescent Ca2+ imaging. Following Pb2+ exposure, there was a dose-dependent decrease in cell viability. Overexpression of TRPC1 increased Pb2+-induced cell death, while knockdown of this channel attenuated cell death. There was increased entry of Pb2+, as measured by inductively coupled plasma mass spectrometry (ICP-MS), following overexpression of TRPC1. Conversely, knockdown of TRPC1 led to a decrease in Pb2+ influx. Down-regulation of STIM1 by RNA interference attenuated the Pb2+ influx, and transfection with a mutant STIM1, which could not gate TRPC1, had a similar effect. Co-transfection of mutant STIM1 and mutant TRPC1, which restore the electrostatic interaction between STIM1 and TRPC1, resumed Pb2+ entry in HEK293 cells. Down-regulation of TRPC1 by RNA interference decreased Ca2+ influx whilst its overexpression increased Ca2+ entry in HEK293 cells. These results suggest that TRPC1 is involved in the cytotoxicity and entry of Pb2+ through molecular interactions with STIM1 and subsequent Ca2+ influx in HEK293 cells.

Differential regulations of ASICs and TRPV1 by zinc in rat bronchopulmonary sensory neurons (712.3)

Zinc, a divalent heavy metal ion and an essential trace element in body, functions as a signaling molecule that regulates a variety of neuronal functions. In this study, we examined the effect of zinc on two populations of acid sensitive ion channels, acid‐sensing ion channels (ASICs) and transient receptor potential vanilloid receptor‐1 (TRPV1), in rat bronchopulmonary sensory neurons. In our patch‐clamp recordings, ASIC currents were induced by a pH drop from 7.4 to 6.8 or 6.5 in the presence of capsazepine (10 µM), a specific TRPV1 antagonist. Our data showed that pretreatment with zinc (50 or 300 µM, 2 min) displayed different effects on the two distinct phenotypes of ASIC currents: a marked potentiation on ASIC channels with fast kinetics of activation and deactivation, or no significant effect on ASIC currents with slow activation and deactivation. On the other hand, pretreatment with zinc significantly inhibited the acid (pH 5.3 or 5.5)‐induced TRPV1 currents in these sensory neurons. The inhibition was effectively abolished by the intracellular application of a selective zinc chelator TPEN (25 µM) indicating that the inhibitory effect of zinc on TRPV1 channels depends on its intracellular binding to these channels. In summary, our study showed that zinc differentially regulates the activities of ASICs and TRPV1 channels in rat bronchopulmonary sensory neurons.Grant Funding Source: Supported by funds from AHA, MEDCEN and MUSM

GROUP SEPARATION OF HEAVY METALS FOLLOWED BY SUBSEQUENT AND INDIVIDUAL SEPARATION OF LANTHANIDES BY CHELATION CHROMATOGRAPHY

A new method was developed for group separation of some heavy metals (HMs) from rare earth elements (REEs) followed by online individual separation of REEs. Various chelating agents were used as mobile phases such as DTPA, PDCA, NTA, HIBA, and oxalic acid. These chelating agents were selected with different numbers of carboxylic acid groups and various geometrical structures which control the elution capability and the separation efficiency. The results showed that selective group separation of HM from REEs could be achieved by different options including 0.0005M PDCA at pH 1, 0.005M DTPA at pH 2, 0.1M AHIBA at pH 2, or 0.0007M NTA at pH 2. The selective elution of HM is attributed to the stronger complex formation between the carboxylic acid groups of the chelating agent with divalent HM ions than with trivalent REE ions especially at relatively low pH values. NTA chelating agent was selected for further investigation to test the individual separation of REEs. Finally, the optimum chromatographic conditions showed that HREEs and IREEs could be efficiently separated by 0.001M NTA at pH 3 while LREEs were separated by 0.005M AHIBA at pH 4 followed by 0.001M PDCA at pH 2.

Efficiency of Cu(II) Removal From Aqueous Media as a Function of Algal Extract Polysaccharide Content

Proper stewardship of our environment necessitates biodiversity preservation and the wise use of resources. Species that may be pests, such as some algae, may also be used innovatively to mitigate their ecological impact. In this study, we extracted polysaccharide mixtures from three algae-Undaria, Laminaria, and Ulva-under three sets of conditions. The nine extracts contained different polysaccharide compositions and varying carboxylic acid contents. The extracts were converted into their respective algal gels by polyion complex formation with chitosan. The gels were examined for their ability to remove Cu(II) ions from aqueous solutions by ion exchange. The removal efficiency was dependent on the algae extraction conditions, which affected the polysaccharide content of the extracts. Among the gels, those derived from the alkaline extractions of Undaria and Laminaria exhibited higher Cu(II) removal efficiencies than from the other extracts. Gels prepared from extracts with higher uronic acid contents exhibited better removal Cu(II) efficiencies. We expected that an extract’s carboxylic acid content would be proportional to its removal efficiency, because the acidic groups in the polysaccharide bind to the divalent heavy metal ions. However, this proportionality was not observed: extracts that included sulfated polysaccharides were less efficient at ion removal, despite their carboxylic acid content. This can be explained by the structural differences in the adsorption sites between alginate and those of the sulfated polysaccharide. Thus, an environmental deficit was converted into a potential economic benefit in the removal of heavy metals from water.

Ethylene glycol tetra-acetic acid and salicylic acid improve anti-oxidative ability of maize seedling leaves under heavy-metal and polyethylene glycol 6000-simulated drought stress

Stress caused by divalent heavy metal ions and drought exert many toxic and adverse effects on seedling growth and development of plants, especially on leave growth. Organic acids such as ethylene glycol tetra-acetic acid (EGTA) and salicylic acid (SA) have been shown to alleviate the unfavorable effects exerted by these stresses on seedling growth and metabolism. In order to reveal the physiological mechanism underlying these toxic effects and the alleviated effects exerted by organic acids, maize seedling leaves (genotype “Zhengdan958”) were exposed for 7 days to different concentrations of cadmium (Cd2+), mercury (Hg2+), and lead (Pb2+) ions and to the drought stress-inducing polymer polyethylene glycol (PEG) 6000. The same experiments were also carried out in the presence of EGTA or SA. Treated leaves were analyzed for activities of the anti-oxidative enzymes catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) and for the content of malondialdehyde (MDA). The results showed that stress treatments with the heavy metals Cd2+, Hg2+, and Pb2+ and with PEG all affected the activities of CAT, POD, and SOD, although the extent and patterns of these changes were different under different stress conditions. Both heavy metal and drought stress caused a concentration-dependent increase in MDA content. Treatments in the presence with EGTA or SA showed that both these compounds exerted certain alleviative effects on seedling growth under Cd2+, Hg2+, and Pb2+ stresses and PEG-simulated drought stress, with SA generally showing better effects than EGTA.

Synthesis of Luminescent CdTe Nanorods on Anodized Aluminum Oxide Template and Their Utility in Divalent Heavy Metal Ion Sensing

A simple one-pot hydrothermal method to grow luminescent CdTe nanorods on porous anodized aluminum oxide (AAO) template is described. These CdTe nanorods on the AAO template were further applied as an optical probe to detect divalent heavy metal ions such as Hg, Pb, Mg and Zn, by examining its photoluminescence (PL) responses. The presence of Pb and Hg ions quenched the photoluminescence (PL) of the CdTe nanorods where as Zn and Mg ions enhanced it with the effect of red shift in the peak position respectively. These PL enhancements/quenching of the nanorods after exposing to the divalent ions were explained on the basis of the active surface related recombination, which depends on the direction of carrier transfer mechanism i.e. from nanorods to the surface adsorbed metal ions or vice-versa and is attributed to the alignment of bands thus formed. The luminescent CdTe nanorods grown on AAO template was found to be effective in sensing metal ions (Pb, Hg, Zn and Mg) up to a micro-molar concentration.

Cysteine-grafted nonwoven geotextile: A new and efficient material for heavy metals sorption – Part A

Cysteine is an interesting biomolecule in the heavy metals trapping field, thanks to its amino, thiol and carboxylic groups. This amino acid is indeed present in some natural chelating agents: glutathione, phytochelatins and metallothioneins. However, cysteine has never been used in remediation processes. When immobilized on a polypropylene nonwoven (PP) geotextile, an innovative and eco-friendly material is obtained, with potential use in drainage and filtration of wastewaters and sediments. PP was first functionalized with acrylic acid using a low pressure cold plasma process to bring reactive carboxylic functions onto the surface (PP-g-AA). Cysteine was then covalently grafted on this modified PP. The cysteine grafting on PP-g-AA was optimized using response surface methodology, which allowed concluding that the best conditions of immersion without heating consist in: a solution containing 0.229 mol/L of cysteine for 28 h. The materials were characterized by Scanning Electron Microscopy, InfraRed Spectroscopy and X-ray Photoelectron Spectroscopy: evidence of covalent cysteine grafting was given. Preliminary sorption tests at 20 °C and pH = 4.5 with artificially polluted solutions give promising results for divalent heavy metal ions: 95 mg Cu (II) (CuSO4 solution), 104 mg Cu (II) and 135 mg Pb(II) (with NO3− counter-ion) per gram of PP are trapped.