Fixation Of Cu Research Articles

Effective fixation of Cu(II) and Cr(III) in solution by food waste biochar – Innovative and valuable treatment method for municipal solid waste

Enhancing biochar's adsorption and solidification performance in compound-polluted aqueous solutions remains a crucial task for achieving the cost-effective removal of heavy metals from water bodies. The study examined the removal performances and mechanisms of Cu(II) and Cr(III) using biochar prepared from food waste at temperatures of 350 °C, 450 °C, and 550 °C (FWB-350, FWB-450, and FWB-550). FWB-450 exhibited the highest overall effectiveness in adsorbing Cu(II) and Cr(III), demonstrating the adsorption capacity (Qe) of 40.283 and 21.456 mg/g in single-solution, respectively. Thermodynamic parameters indicate that the adsorption process involves physical and chemical reactions involving heat absorption. The impact of Cr(III) on the adsorption of Cu(II) is more apparent in the mixed competitive system. The pH, the oxygen-functional groups and carbonate ion quantity of FWB are crucial in improving Cu(II) and Cr(III) adsorption by affect the hydrolysis, complexation, and ion exchange processes. The presence of alkaline earth metal ions in FWB, like Ca(II), aids in the elimination of Cu(II) and Cr(III) through ionic precipitation and ion exchange, correspondingly. Furthermore, FWB adsorbed with Cu(II) and Cr(III) is relatively less hazardous than solid waste. The study validates the resource utilization of FW and its potential application of biochar in heavy metal adsorption.

In-situ Cu-doped carbon-supported catalysts applied for high-salinity polycarbonate plant wastewater treatment and a coupling application

• Cu and N doped biochar (Cu@NBC) was fabricated from the waste adsorbent. • The Cu@NBC/PDS system equipped with resistance to anions in high-salinity wastewater. • Cu@NBC can be uniformly deposited onto the PSF membrane. • Cu@NBC/PSF membrane exhibited instantaneous catalytic performance. • Electron-transfer process can inactivate bacteria to relieve membrane fouling. Organic pollutants decomposition in high-salinity wastewater is still a challenge for environmental restoration due to the inhibitory effects results from the consumption of radicals by anions. Herein, we demonstrated a non-radical oxidation process via the peroxydisulfate (PDS) activation rather than photocatalysis by the Cu 2+ adsorbed adsorbent-based nitrogen doped biochar (Cu@NBC) for efficiently decontaminating polycarbonate plant wastewater (PCW). After the pyrolysis, the Cu 2+ in the waste biosorbent were reduced to Cu 2 O, and the N-doping improved the fixation of Cu and the formation of Cu 2 O. Through both dynamic fitting and characterization analysis, the critical role of Cu 2 O in PDS activation rather than photocatalysis was revealed for the first time. Different from always reported 1 O 2 dominated non-radical process, an electron-transfer mechanism involving surface metastable species was proved to play a key role in the Cu@NBC/PDS system. Benefit from the electron-transfer process, the Cu@NBC/PDS system equipped with high resistance to the anions in high-salinity wastewater. The results indicated that BPA as well as chemical oxygen demand (COD) could be effective removal within 90 min. We further deposited the activator on an ultrafiltration membrane and exhibited a rapid oxidation of BPA as the wastewater passed through the filter, and the composite membrane can effectively inactivate bacteria, which will provide a safety strategy for mitigation of membrane fouling.

Mechanisms of copper immobilization in Fluvisol after the carbon sorbent applying

Biochar is widely used sorbent for soil remediation but the mechanism of its effect on immobilization of metals and particular processes of metal transformation are still unclear. We designed an incubation experiment to investigate the impact of wood biochar to copper (Cu) contamination in Calcaric Fluvisols Loamic. The efficiency of biochar implementation for reduction of Cu mobility in soil has been studied using combined method of heavy metal fractioning (Minkina et al., 2013). It was shown that the use of sorbent into polluted soil results in the change of fraction-group composition of metal compounds, fixation of Cu due to reduction of weakly bound forms and increase of the part of residual and metal fractions strongly bound with organic matter. Decrease of pollutant mobility occurs along an increase of the dose of a sorbent. The greater effect was observed after use of biochar in the concentration 2.5 %. Thus, the present study demonstrates the possible remediation of soil contaminated by heavy metals using biochar and provides a particular strategy for remediation of soils contaminated with Cu.

Copper micronutrient fixation kinetics and interactions with soil constituents in semi-arid alkaline soils

ABSTRACTThis study examined the fixation pattern and kinetics of plant-available [diethylene triamine pentaacetic acid (DTPA)-extractable] copper (Cu), as well as basic soil properties that influence Cu availability in selected semi-arid soils. Soil samples from six different series were used and data obtained from Cu extraction experiments fitted to various kinetic models. Soils were also characterized for a suite of chemical and physical properties. The majority (80%) of the plant-available Cu fixed over the experimental period of 90 d occurred within the first 14 d. The amount of plant-available Cu fixed within the first 14 d tended to be influenced by the combination of organic matter (OM) and pH. The total amount of Cu fixed at the end of the experimental period of 90 d was influenced by pH and a combination of pH and calcium carbonate. The fixation of plant-available Cu over the experimental period was better described by the power function model [R2 = 0.90, Standard Error (SE) = 0.099] but poorly by the other models (R2: 0.58 to 0.59), while reactions within the first 35 d were better described by the second-order model (R2 = 0.98, SE = 0.008), suggesting a different fixation pattern. Findings from this study provide a basis for a more mechanistic approach to evaluating and comparing the fixation of Cu micronutrient compounds in these semi-arid soils for more scientific management decision making.

Fractionation of copper and cadmium and their binding with soil organic matter in a contaminated soil amended with organic materials

Purpose The contamination of agricultural soils by heavy metals is a worldwide problem. Organic amendments can be used for the immobilization and binding of heavy metal ions in soils by complexation, adsorption, and precipitation. A field trial was carried out to evaluate the influence of some low-cost organic materials such as rice straw (RS), green manure (GM), and pig manure (PM) on the distribution of Cu and Cd and the retention of these metals by organic matter fractions in heavy metal-polluted soils. Materials and methods The experiment was conducted in Miaoyunao Village, Daye County, Hubei province, China. PM, GM (peanut plants), and RS were obtained from a farm close to the village. Sixteen treatments with three replicates were designed. Soil chemical properties such as soil pH, electrical conductivity (EC), organic matter (OM), and available P were measured by standard methods. Soluble/ exchangeable, organic-bound, inorganic precipitates and residual Cu and Cd in the soil were sequentially extracted and analyzed. The amounts of Cu and Cd bound with soil particulate organic matter (POM) fractions and humic substances were also determined. Results and discussion The addition of organic amendments declined significantly the concentrations of soluble/ exchangeable Cu and Cd, but increased the amounts of these metals in organic-bound and inorganic precipitate forms in the soil. RS was more effective than GM and PM in diminishing the solubility of Cu and Cd. The largest retention for Cu and Cd by humic substances and POM was noticedinRStreatments,whereasthelowestwasfoundinPM treatments. Humic substances showed higher potential in the fixation of Cu and Cd than POM fractions. The conversion of soluble/exchangeable Cu and Cd to other insoluble forms after the application of organic amendments may be ascribed to the increases of soil OM, pH, EC, and available P contents. The highest binding of Cu and Cd with POM fractions and humic substances after the incorporation of RS mainly resulted from the greatest increase of soil OM contents. Conclusions RS, GM, and PM can be employed as good and cheap substances for the immobilization of Cu and Cd in heavy metal-polluted soils. RS was the best amendment in decreasing the solubility of Cu and Cd, and also in enhancing the retention of these metals by humic substances and POM fractions in the soil. Futures studies should focus on the influence of these organic amendments or their mixtures on the phytotoxicity of Cu and Cd for different plants in heavy metal-contaminated soils.

Modelling the effects of ageing on Cd, Zn, Ni and Cu solubility in soils using an assemblage model

SummaryAgeing reactions can reduce trace metal solubility and can explain natural attenuation of contaminated soils. We modelled ageing reactions in soil with an assemblage model that considers slow reactions in Fe‐oxyhydroxides and reversible sorption on organic matter and clay minerals. Metal adsorption kinetics on Fe‐oxyhydroxides was obtained from data with synthetic oxyhydroxides. Metal solubility and isotopic exchangeability data were obtained from 28 soils amended with Ni, Zn, Cu and Cd metal salts and monitored for 850 days. The assemblage model was constructed in WHAM 6.0 and used soil properties and dissolved organic matter as input data. The model was first validated to predict dissolved metal concentrations, based on the concentration of isotopic exchangeable metals. The model overestimated metal solubility without parameter adjustment by mean factors of 4–7, and successful fits were obtained by increasing the specific surface area of Fe‐oxyhydroxides from measured values of synthetic systems to a value of 600 m2 g−1 recommended by other authors. The effect of ageing on the isotopic exchangeable metal fraction was subsequently modelled starting from the predicted fraction of metals present on Fe‐oxyhydroxides immediately after soil spiking. The observed isotopic exchangeable metal fractions of Ni, Zn and Cd agreed reasonably well with predicted values. The model predicts that ageing reactions are more pronounced at higher pH because metal sorption is increasingly directed to oxyhydroxide surfaces with increasing soil pH. Modelling fixation of Cu requires more information on fixation of that metal in organic matter.

Removal of Cu from aqueous solutions by synthetic hydroxyapatite: EXAFS investigation

The sorption of aqueous Cu on synthetic hydroxyapatite has been investigated by means of the results of a combined structural simulation and extended X-ray absorption fine structure (EXAFS) analysis. The removal of Cu was studied in batch experiments at 25 ± 2 °C. The sorption of Cu follows Langmuir behaviour and was attributed to a two-step mechanism involving surface complexation and ion exchange with Ca resulting in the formation of a copper-containing hydroxyapatite. EXAFS results suggest that the heavy metal is present in the Cu 2+ form. The structural experimental and theoretical analysis shows that Cu is bond to about four O atoms at a distance of about 1.95 Å. In all the studied cases the immobilization site of Cu is the same. The fixation of Cu occurs in the surface sites of hydroxyapatite whereas the sorption in the Ca sites in the inner part of the structure is unlikely.

Role of soil constituents in fixation of soluble Zn, Cu, Ni and Cd added to soils

SummarySlow immobilization of trace metals in soil, termed ‘fixation’, affects their natural attenuation but it is still unclear which reactions occur. Twenty‐eight soils were selected to assess the role of Fe oxides and carbonates on fixation of Cu, Cd, Zn and Ni. Soils included samples from 2 toposequences (Vietnam, Spain) and 13 European topsoils with different soil characteristics (pH 3.4–7.7). Samples were amended with 250 mg Zn kg−1, 100 mg Cu kg−1, 80 mg Ni kg−1 and 2.5 mg Cd kg−1 as metal salts and incubated for 850 days. Fixation was measured as the increase of the fraction of added metals that were not isotopically exchangeable. Fixation increased with time and was, averaged over all the soils, 43% (Cu), 41% (Zn), 41% (Ni) and 28% (Cd) after 850 days. Metal fixation within samples from each toposequence was generally positively related to total Fe oxide concentration (Fed) for Zn, Ni and Cd. However, the fixation of Cd, Zn and Ni was mainly explained by pH and not by Fed when considering all soils. Fixation of Zn and Cd in soils with pH >7.0 increased with increasing concentrations of carbonates at initial ageing times. Fixed fractions of Zn, Ni and Cd were significantly released when experimentally removing 50% of carbonates by acidification. Fixation of Cu was most poorly related to soil properties. Our data suggest that fixation of Cd, Zn and Ni is related to a pH‐dependent diffusion into oxides and that of Cd and Zn also to diffusion and/or coprecipitation in carbonates. Fixation of Ni at neutral pH may also be related to stabilization of precipitates that form readily in soil.

Interactions Study between the Copper II Ion and Constitutive Elements of Chitosan Structure by DFT Calculation

Molecular modeling is particularly useful to understand interactions between various kinds of molecules and ions. This study is aimed at studying the interactions between one Cu(2+) ion and one or several glucosamine residues. The geometries and the interaction energies of all of the complexes involving all of the dimers obtained from glucosamine and N-acetylglucosamine were computed by means of density functional theory (DFT) methods. In a first step, for the two dimers A-A and A-B (A for glucosamine and B for N-acetyl glucosamine), a starting geometry was built, and the energies were calculated using a rigid rotation of 30 degrees intervals for each of the dihedral angles (Phi and Psi) of the glycosidic bond, spanning the whole angular range. These calculations allowed us to retrieve the minimal energy conformation and investigate all possible conformations. The results were compared to some experimental data. In a second step, we investigated the interactions of Cu(2+) with the different possible coordination sites of A. For all complexes considered, the Cu(2+) site was completed with H(2)O and/or OH(-) ligands to have a global neutral charge. The calculations confirmed that the most stable interactions involved the free amino site in a "pending complex". Another pending form was possible considering the participation of the heterocyclic O site, but the latter was less favored. On the other hand, we also showed that glucosamine could not act as a bidentate ligand and that N-acetyl glucosamine was not coordinating with Cu(2+). Finally, our results evidenced a cooperative fixation of Cu(2+) ions when considering the complexation of two successive metal ions on the two consecutive glucosamine residues of the dimer A-A.

Distribution of Selected Heavy Metals in Sediments of the Águeda River (Central Portugal)*

The state of river water deterioration in the Águeda hydrographic basin, mostly in the western part, partly reflects the high rate of housing and industrial development in this area in recent years. The streams have acted as a sink for organic and inorganic loads from several origins: domestic and industrial sewage and agricultural waste. The contents of the heavy metals Cr, Cd, Ni, Cu, Pb, and Zn were studied by sequential chemical extraction of the principal geochemical phases of streambed sediments, in the <63 μm fraction, in order to assess their potential availability to the environment, investigating the metal concentrations, assemblages, and trends. The granulometric and mineralogical characteristics of this sediment fraction were also studied. This study revealed clear pollution by Cr, Cd, Ni, Cu, Zn, and Pb, as a result from both natural and anthropogenic origins. The chemical transport of metals appears to be essentially by the following geochemical phases, in decreasing order of significance: (exchangeable + carbonates) ≫ (organics) ≫ (Mn and Fe oxides and hydroxides). The (exchangeable + carbonate) phase plays an important part in the fixation of Cu, Ni, Zn, and Cd. The organic phase is important in the fixation of Cr, Pb, and also Cu and Ni. Analyzing the metal contents in the residual fraction, we conclude that Zn and Cd are the most mobile, and Cr and Pb are less mobile than Cu and Ni. The proximity of the pollutant sources and the timing of the influx of contaminated material control the distribution of the contaminant-related sediments locally and on the network scale.

ALTERAÇÃO SUPERGÊNICA DO DEPÓSITO DE COBRE-OURO DO SALOBO, SERRA DOS CARJÁS-PA - ÊNFASE NO COMPORTAMENTO DO COBRE

The weathering mantle of the Salobo deposit was developed upon metagraywackes with interbedded lens of iron formations. The profile is of the truncated type and constituted, from the base to the top, of a transition horizon, a saprolitic horizon and colluvial deposits. The two former horizons show lateral, textural and mineralogical variations which reflect the heterogeneous nature of the parent rock. Thus, alteration of the barren graywackes resulted essentially in the formation of a saprolite rich in clay minerais (hydrobiotite, smectite, kaolinite). On the other hand, weathering of the iron formations, host-rocks of copper sulfides (bornite, calcocite, chalcopyrite), originated a gossan type profile composed from the base to the top of a supergene sulfide zone, an oxidized minerais zone and a ferruginous saprolite. The supergene sulfides are digenite, covellite and bornite (?) while cuprite, malachite, azurite and native copper constitute the oxidized copper assemblage. Within the saprolite, smectite and goethite are the main copper enriched minerais. The evolution of such supergene setting involved oxidization and dissolution of primary sulfides with mobilization of Cu and Fe as soluble sulfatos. The downward and lateral transfer of these metais caused the formation of new mineral associations according to the Cu/S ratio in the solutions and the ambient pH and Eh conditions.In the reducing zone the ionic exchange between copper sulfate and primary sulfides yielded mainly digenite and covellite, while in the water-table fluctuation zone and immediately above, in more oxidizing conditions, copper precipitated as cuprite and native metal. Besides, reaction of copper sulfate with calcite from veins that cuts iron formations resulted in the fixation of Cu as malachite and azurite in neutral to alkaline conditions. In the Carajas region, the lateritic mantle was formed during the Lower Tertiary, but, during the Upper Tertiary and Quaternary, underwent dissection due to regional uplift. Thus, in the Salobo area, the duricrust and the upper saprolite were removed. Each phase of lowering of the hydrostatic levei resulted in the deepenning of the weathering profile and alteration, in oxidizing conditions, of previously formed supergene oxides and sulfides. One parte of the released copper then underwent downward leaching and reprecipitation in deeper reconstituted cementation and oxidation zones, while another part was fixed by neoformed goethite and clay-minerals.

Removal of metal ions from aqueous solution on low cost natural polysaccharides: Sorption mechanism approach

The fixation of Cu 2+, Ni 2+ and Pb 2+ on sugar beet pulp, a low-cost material, has been studied. After a simple treatment of the sorbent, the results have shown that the mode of fixation depends on the metal. The key part of the mode of fixation is attributed to ion exchange, while a non-negligible part of adsorption could sometimes occur. As far as lead ions are concerned, 25% of their fixation capacities are due to adsorption mechanism at pH 4. The overall uptake is at a maximum at pH 6 and gives up to 60 mg g −1 for Pb 2+, 30 mg g −1 for Cu 2+ and 12 mg g −1 for Ni 2+, which seems to be removed exclusively by ion exchange. These capacities increase with the pH. Diffusion models have been tested on samples of different particle size, and they have suggested a transfer to the intraparticular sites.

Bacterial fixation of Cu and Fe in Ogoya Mine, Ishikawa Prefecture

Bacterial fixation of Cu and Fe in Ogoya Mine, Ishikawa Prefecture

Effects of thyroparathyroidectomy and of thyroxin and calcitonin on the tissue distribution of twelve elements in the rat

The effects of thyroparathyroidectomy (TPTY) and of replacement therapy using thyroxin (T4) and calcitonin (CT) on the tissue distribution of elements were studied in the rat under semichronic conditions. The elements Na, K, Ca, Mg, Fe, S, P, Rb, Sr, Mn, Cu, and Zn were determined in whole blood, plasma, brain, liver, heart, kidney, skeletal muscle, and bone. TPTY modified concentrations of all elements tested but only small changes were observed for K, Mg, S, and P. The mineral bone composition was slightly modified, 28 d after TPTY, whereas plasma was the most altered. The consequences of TPTY were corrected fairly well by T4 for Na, Cu, Zn, Fe, and S, and by CT for K, P, Rb but with less efficiency for Ca. This study revealed that hormones of the thyroid gland, mainly T4, play an important role in the plasma and tissue balance of elements. It is suggested that T4 participates in tissue fixation of Cu, Zn, and Fe and that CT influences phosphoremia and cellular Ca binding.

Some unusual geochemical features of the oxidized zone at the central sector of the Singbhum copper belt, India

Incipient removal of Cu even from the caprocks, in situ transformation of sulphides to oxidized compounds, fixation of substantial Cu by supergene ‘clay’ minerals, virtual absence of secondary sulphide enrichment, and non-congruence between present water table and the ‘bottom’ of oxidized zone are the unusual features observed in the oxidized profile at Chapri mining-block within the Singhbhum copper belt. Petromineralogical studies of ore and host-rock samples from drill cores, and in situ measurement of Eh-pH values of mine and surface water furnish an explanation for the observed features. Occurrence of low-pyrite orebodies as sheeted veins and disseminations accounts for localized, inadequate generation of strong acids that was readily consumed by hydrolysis reactions in host rock. This inhibited any significant migration of Cu, outwards or downwards, by: (a) precipitating oxidized compounds; and (b) fixation of Cu in supergene, neoformed clay minerals. Vertical zoning of copper minerals in the oxidized profile is consistent with stability diagrams and with measured Eh-pH values. The ‘bottom’ of the oxidized zone presumably represents a palaeo-water table, tilted in sub-recent time. Preliminary leaching experiments indicate feasibility of exploitation of Cu left out in the oxidized zone.

Zinc and Copper Sorption and Fixation by an Acid Soil Clay: Effect of Selective Dissolutions

AbstractCopper and zinc sorption‐desorption studies were carried out over a range of pH values using clay fractions separated from two horizons of an acid soil from New York. In the pH range of high sorption, as much as 95% of the sorbed metal could not be desorbed by several washes with 0.05M CaCl2 and thus was considered fixed. Sorption and fixation of Cu and Zn increased rapidly above pH 4 and 5, respectively, for the whole soil clays. Following removal of the oxide fraction by oxalate and citrate‐dithionite extractions, sorption and fixation were reduced considerably at pH values below the onset of hydrolysis of the metals in bulk solution, indicating a significant role of the oxides in metal retention. Citrate‐dithionite extraction was more effective than oxalate in reducing Zn sorption and fixation, suggesting a significant influence of the more crystalline iron oxide fraction. These extraction procedures had less effect on the ability of the clays to sorb and fix Cu. Treatment of the clays by hypochlorite to remove organics tended to either enhance or have little effect on sorption and fixation of Cu and Zn. It is concluded that microcrystalline and noncrystalline oxides in the clay fraction of this soil, representing &lt; 20% of the clay by weight, provide reactive surfaces for the chemisorption of Cu and Zn. At low pH, adsorption at these surfaces may be the dominant mechanism of heavy metal immobilization, especially in the subsoil horizons.

Trace-element studies of the Precambrian stromatolitic phosphorites of Udaipur, Rajasthan, India

Thirty-eight samples from the Matoon and Dakan Kotra phosphorite deposits, Udaipur region, Rajasthan, were analysed for P 2O 5, Cu, Ni, Co, Pb, Zn, Cr, Sr, Rb, V, Li, Ag, Cd, U and Th contents by spectrophotometer, atomic absorption and X-ray fluorescence. The dominant phosphate minerals are collophane and francolite whereas quartz, calcite and dolomite are the main gangue minerals, and sericite, muscovite, limonite and carbonaceous matter are present in small amounts. Sr, V, Cr, Pb and Zn have a positive correlation with P 2O 5 and are adsorbed by phosphate minerals. The fixation of Cu, Ni, Co, Rb, Li, Ag, Cd, U and Th seems to be geochemically controlled by the biogenic activity of fossil algae and are antipathetic or feebly correlated to P 2O 5. Rb and Li were possibly adsorbed by clay minerals. The pre-existing Banded Gneissic Complex, which occurs close to the phosphorite deposits of the Udaipur region, might be the source rock from which phosphorus, along with lime and silica, were derived and concentrated, probably in a marine environment in a more or less restricted basin of deposition. The Th/U ratio suggests a slightly reducing to fairly oxidizing condition at the site of deposition.

Etude expérimentale de la fixation de métaux par un matériau sédimentaire actuel d'origine algaire—II. Fixation ‘in vitro’ de UO 2+2, Cu 2+, Ni 2+, Zn 2+, Pb 2+, Co 2+, Mn 2+, ainsi que de VO −3, MoO 2−4 et GeO 2−3

The ‘in vitro’ metal fixation ability of a recent sedimentary organic matter of algal origin has been investigated with seven divalent cations (UO 2+ 2, Ni 2+, Mn 2+, Zn 2+, Co 2+, Pb 2+, Cu 2+) and three anionic species (VO − 3, MoO 2− 4, GeO 2− 3). In the case of the cations, the great selectivity of the fixation, the independence of the amounts of metal fixed with regard to the cation exchange capacity of the organic matter and the existence of a ‘pH effect’, suggest the fixation mechanism to be a complexation-chelation process. The similarities between the cation fixation capacity vs pH curves [in the 2 to (4–7) pH range]emphasize the existence of a common and determining step in the chelation mechanism for all the cationic species studied. We assess this phenomenon to be an interaction between the cationic species and anionic carboxylate groupings. This first, non-selective, interaction is supposed to be followed by the formation of selective linkages between the metal and various organic functional groups. Moreover, the thermodynamic expression of these hypotheses allows to take into account, for the cations, both the pH dependence of their fixation capacity and the possibility to apply a Langmuir adsorption model to their fixation on the organic matter. Some competition studies between two cationic species have also been performed. They indicate a good fixation of Cu 2+ vs other metals, but show that the best one seems to be that of UO 2+ 2. As to the anions, the fixation is weak and the anion exchange capacity of the algal organic matter is small. Taking into account the experimental results concerning U, V and Mo and the correlation often observed in caustobioliths between these three elements, we propose a metallogenic scheme for the accumulation of these three metals in such sediments, starting with fixation of metals under oxycationic (or neutral) forms leading to organometallic linkages.

TRANSPORT OF TRACE ELEMENTS IN ECOSYSTEMS OF THE BÄRHALDE WATERSHED IN THE SOUTHERN BLACK FOREST

Concentrations of trace elements and macroelements in rainfall, canopy drip, runoff, and soil solution have been determined each week at four free-drained and three hydromorphic sites at an altitude of 1000 to 1300 meters above sea level in the very humid, cool Black Forest. Among these elements, the turnover of beryllium, cadmium, copper and lead are discussed in detail. Beryllium had the lowest input and the highest output of these four elements. It was primarily mobilized in the mineral topsoil, and only a small amount was readsorbed by humic acids or subsoil or taken up by plants. Lead concentrations were highest in precipitation, but only about 5 percent of the input appeared in the output. Cadmium, Cu, and Pb were all adsorbed by the humus and iron oxide accumulation horizons of podzols and Ockererde. Copper was adsorbed in all soils except podzols, and fixation of Cu was especially obvious in the Ockererde. Cadmium was not highly adsorbed in mineral soil. The recent increase in atmospheric input resulted in an enrichment and rise of turnover for Cd, Cu, and Pb throughout the watershed.

Enhanced capacity of chitosan for transition-metal ions in sulphate-sulphuric acid solutions

Batch measurements have shown that the collection yields of chitosan for chromium(III), iron(III), nickel, copper(II), zinc and mercury(II) from sulphuric acid solutions are higher when the solutions contain ammonium sulphate, or when chitosan conditioned in ammonium sulphate is used, particularly at pH 3·0 and 5·0. The contrary is verified for the oxy-anions vanadate, chromate and molybdate. Manganese is never collected. At pH 1·0 no collection occurs. A procedure for recycling chromatographic columns includes fixation of Cu or Ni from a sulphate solution at pH 3–5 on sulphate-conditioned chitosan, and elution with 0·1 M sulphuric acid/0·1 M ammonium sulphate at pH 1·0; the presence of sulphate in the eluent obviates the detrimental effect of sulphuric acid on the next cycle. Sulphate is the favoured counter-ion of the chelated cations and its action produces shorter chromatographic bands. The interaction of sulphate with chitosan is discussed in terms of crystallinity and steric distribution of the protonated amino-groups in the polymer. Data on the new diethylaminohydroxypropylcellulose are included.