Computerprogramm „ADSORB”︁ — ein optimiertes mathematisches Verfahren zur Charakterisierung organischer Vielstoffgemische in Wässern mittels Adsorptionsanalyse

The computing program ?ADSORB”? allows a very fast mathematical evaluation of adsorption isotherms for the preparation of adsorption analyses. With the program ?ADSORB”? it is possible to calculate any number of pseudocomponents of organic multicomponent mixtures of different adsorbability. Only few minutes are required for the mathematical evaluation of an sorption analysis by means of ?ADSORB”?. adsorption analysis, adsorption isotherm, mathematical modelling     

Kationenaustauschkapazität als Grundlage für die Schätzung der Schwermetallmigration im Boden

The adsorption/desorption ratio is an important quantity of the displacement of heavy metals in the soil. Adsorption isotherms as controlled quantities are suitable for the development of a transport model. With the aid of the T value the sorption coefficients and distribution quotients can be determined for different soils. By two examples of simulation the migrations of Cd and Pb were calculated with soil samples of warp clay/gley and loam/para-brown earth. It was found, inter alia, that with increasing time of input the concentration of dissolved and adsorbed heavy metals grows and that the added heavy-metal ions are absorbed in the uppermost layers already. For cases of continuous input the simulation model is recommended for the practice to estimate the migration of heavy metals in soils.     

Untersuchungen zur adsorptiven Abtrennung von leichtflüchtigen chlorierten Kohlenwasserstoffen (LCKW) aus huminstoffhaltigen Wässern mit neuartigen Adsorberpolymeren

Investigations of the Adsorptive Separation of Volatile Chlorinated Hydrocarbons (VCHC) from Water with Humic Substance by Novel Polymeric Adsorbents and Activated Carbons. Part I: Isotherms and Kinetics of Adsorption The isotherms and kinetics of adsorption of different volatile chlorinated hydrocarbons (VCHC) (1,2-dichloroethane, 1,1,1-trichloroethane, trichloroethene) and a humic substance from water as well as these VCHC from water with humic substance onto novel polymeric adsorbents (WOFATIT EP 63, DOWEX XUS 43493 and XUS 43546, MACRONET MN 100 and MN 200) were studied in comparison to activated carbons (NORIT ROW 0.8 SUPRA, PRECOLITH BKK 3, HYDRAFFIN CG). It was determined that the novel polymeric adsorbents remove the VCHC well and the humic substance in contrast to the activated carbons only a few. The decrease of the equilibrium loading for the VCHC due to the presence of humic substance is at the activated carbons approximately double as high as at the novel polymeric adsorbents, whereas in the kinetics of adsorption no substantial influences of the humic substance on the mass transfer were determined.     

Verringerung der Schwermetall‐ und Sulfatbelastung in sauren bergbaubelasteten Gewässern durch Aluminiumpräzipitate

Attenuation of Heavy Metals and Sulfate by Aluminium Precipitates in Acid Mine Drainage During the mixing of acid mine waters with nearly neutral tributaries, often precipitates are formed which are high in iron or aluminium. These precipitates cover the river bed for many kilometres. Near the town of Lehesten (Thuringian slate mining area), leachates of slate quarries and waste rock dumps contain high amounts of aluminium, sulfate, copper, nickel, zinc, manganese, and H⁺ ions as a result of the oxidation of incorporated pyrite. These leachates enter the brooks Loquitz, Kleine Sormitz, and Rehbach leading to the phenomenon named above. The contribution of the forming aluminium‐rich precipitates on the attenuation of sulfate and heavy metals by sorption or coprecipitation was studied by analysing the composition of water and sediment samples as well as samples of suspended matter. Sulfate is often considered as conservative tracer in acid mine drainage. However, sulfate does not behave conservatively in this system what might be explained by the adsorption of sulfate to the aluminium precipitates. Instead, conservative behaviour was found for calcium, potassium, chloride, zinc, manganese, and nickel. A formation of jurbanite can be excluded because of the low sulfate contents. The sulfate content of the sediment depends on the pH. At low pH values (4.8) the S/Al ratio corresponds to the theoretical ratio in basaluminite and decreases with rising pH. Sulfate is weakly bound to the solid phase and can easily be replaced by OH^– ions. A formation of basaluminite is possible at low pH values with a fluent transition to aluminium hydroxide. Therefore the precipitates are assumed to consist predominantly of aluminium hydroxide with sulfate being adsorbed to the surface.     

Untersuchungen zur Adsorption von Spuren hydrolysierbarer Metallionen an Oberflächen

In static laboratory experiments there are determined quantities influencing the adsorption of selected metal ions on different surfaces (base metals, glass of instruments, quartz glass, plastic materials, precious metals). A great dependence on pH, ionic species, ionic concentration, material as well as temperature and presence of complexing agents is observed. Processes are proposed or confirmed by which the losses of material during the trace analysis are reduced.     

Zur Adsorption von Dichlormethan und 1,1,1-Trichlorethan aus Modellabwässern mit Adsorberpolymeren und Aktivkohlen

Adsorption of Dichloromethane and 1,1,1-Trichloroethane from Synthetic Wastewaters with Polymeric Adsorbents and Activated Carbons Isotherms, kinetics, and dynamics of adsorption of dichloromethane and 1,1,1-trichloroethane from synthetic wastewaters onto novel polymeric adsorbents were investigated in comparison to traditional polymeric adsorbents and activated carbons. The polymeric adsorbents and the activated carbons showed no large differences in adsorption kinetics, whereas the novel, crosslinked polymeric adsorbents exhibited at times higher adsorption capacities than the traditional, not crosslinked polymeric adsorbents and activated carbons.     

Untersuchungen zum Abbau von Pharmaka in kommunalen Kläranlagen mit HPLC-Electrospray-Massenspektrometrie

Examination of the Degradation of Drugs in Municipal Sewage Plants Using Liquid Chromatography-Electrospray Mass Spectrometry Numerous drugs can be identified in the secondary effluent of municipal sewage plants. In order to obtain information about the degree of elimination (adsorption, aerobic degradation) of these compounds, a batch reactor containing different drugs in environmentally relevant concentrations and a suspension of activated sludge was coupled to a HPLC-MS-MS system. During a testing period of three days concentration-time-curves were recorded. For most of the examined drugs (acetamidoantipyrine, crotamiton, diclofenac, primidone, propyphenazone) solely a strong decrease of the initial concentration within the first 15 minutes was observed, which was interpreted primarily as adsorption to the activated sludge. For acetaminophenol and pentoxifyllin an additional slower decrease in concentration within several hours was observed. This slower elimination was interpreted to be caused mainly by primary degradation. It could be shown that dihydrocodeine is oxidized to hydrocodone in the batch reactor. The conjugate acetaminophen glucuronide was cleaved.     

Untersuchungen zur adsorptiven Abtrennung von leichtflüchtigen chlorierten Kohlenwasserstoffen (LCKW) aus huminstoffhaltigen Wässern mit neuartigen Adsorberpolymeren und Aktivkohlen. Teil II:: Dynamik der Adsorption

Investigations of the Adsorptive Separation of Volatile Chlorinated Hydrocarbons (VCHC) from Water with Humic Substance by Novel Polymeric Adsorbents and Activated Carbons. Part II: Dynamics of Adsorption In this publication, the dynamics of adsorption of different volatile chlorinated hydrocarbons (VCHC) (1,2-dichloroethane, 1,1,1-trichloroethane, trichloroethene) and a humic substance from water as well as of these VCHC from water with humic substance onto novel polymeric ad-[QJ][HR] sorbents (WOFATIT EP 63, DOWEX XUS 43493, MACRONET MN 100 and MN 200) was studied in comparison to activated carbons (NORIT ROW 0.8 SUPRA, PRECOLITH BKK 3, HYDRAFFIN CG). The obtained breakthrough curves and the following predicted characteristic values reveal that the polymeric adsorbents do not remove or remove the humic substance only with low adsorption capacity in contrast to the activated carbons. At the adsorption of the VCHC from water with humic substance it was determined that the influence of the humic substance on the adsorption capacity is substantially less on polymeric adsorbents than on activated carbons.     

Untersuchungen zur Einzel- und Gemischadsorption von Phenolen an Aktivkohlen. Teil 3: Zur pH-Abhängigkeit der Adsorptionsgleichgewichte

In order to describe the adsorption of dissociating substances, initially the adsorption isotherms for the borderline cases of undissociated and dissociated substances are experimentally determined. With the aid of the Ideal Adsorbed Solution Theory (IAS Theory) then the calculation is successfully performed for pH-values at which both forms are present side by side. As examples, the systems phenol/activated carbon and p-chlorophenol/activated carbon are examined, and they show a good agreement between calculation and measurement.     

Hydrochemische Ergebnisse zur Aufbereitung stark belasteter Oberflächenwässer und Uferfiltrate mit Kalkhydrat,Teil 1

Several laboratory-scale-tested variants of the treatment of organically loaded surface water samples with hydrated lime are described. Possibilities of the additional application of magnesium, aluminium and iron salts and of the anionic polymer “activated silicic acid” are discussed. The aim has been a considerably reduced application of metallic salts and precipitants at a maximum adsorption of organic pollutants. Another factor influencing crystallization and double hydroxide formation consists in low water temperatures, < 8°C. With the aid of a magnetic treatment disturbing effects were avoided and even increases of the rates of growth and sedimentation were achieved.     

Adsorption Characteristics of β‐Ionone in Water on Granular Activated Carbon

The adsorption performance of β‐ionone on four types of granular activated carbon (GAC) in water was investigated through batch experiments. The effect of initial β‐ionone concentrations and natural organic matter (NOM) adsorbed on GAC, adsorption kinetic and isothermal models were also studied. The results showed that four types of GAC all had good adsorption performance for β‐ionone, the equilibrium adsorption amount of the GAC employed was in the order of YK > GK > MZ‐A > MZ‐B. The adsorption amount increased with increasing initial concentrations. The presence of NOM could reduce adsorption of β‐ionone to a certain extent, and small molecular weight (MW) fractions (particularly <1000 Da) exhibited a remarkably competitive effect on the adsorption of β‐ionone. The experimental data showed good correlation with pseudo‐first‐order model. Furthermore, adsorption of β‐ionone on GAC fitted Freundlich, Langmuir, and Tempkin isotherms in the range of experimental concentrations, but followed Freundlich isothermal model most appropriate. The thermodynamic parameters were calculated by the results of the experiment, which showed adsorption of β‐ionone on GAC as being endothermic and spontaneous.     

Adsorption organischer Substanzen unterschiedlicher Molekülgröße an Adsorberpolymeren

Wofatit Y 77 is presented as a novel non-ionogenic hydrophilic adsorbing polymer having a large specific BET surface (800 … 1500 m²/g) and a narrow pore size distribution. By the example of selected aromatic compounds with different molar masses it is shown on the basis of the adsorption of individual substances that the adsorption capacity primarily depends on the molecular size and not on the specific inner surface of the adsorber polymer. Favourable possibilities are derived from that for.     

From surface acidity to surface reactivity; inhibition of oxide dissolution

Paul Schindler's early work on the acid-base chemistry of oxides was instrumental for the development of the concept of surface complexation. This approach has not only been important in establishing a theory on the adsorption of metal ions and ligands as a function of pH and solution variables, but has become essential in establishing surface speciation (coordinative structural and electronic arrangement at the solidwater interface) which in turn determines surface reactivity. The factors that affect dissolution of Fe(III) (hydr)oxides and inhibition of dissolution are discussed. A few examples for the inhibition of reductive and ligand-promoted dissolution by binuclear complexes of oxoanions (phosphate, borate) and of protonpromoted dissolution by Cr(III) are given.     

Zum Leistungsvermögen makroporöser Adsorberpolymere bei der Elimination organischer Mikroverunreinigungen

In laboratory experiments the adsorption of eleven different organic substances in water is individually tested in the range of concentration of 0.2… 5.0 mg/l on EP 60 and EP 61 (styrene-divinylbenzene, non-polar) and EP 62 and Y 59 (acrylic-acid-ester-divinylbenzene, polar). In batch experiments the elimination at 1… 2 g/l adsorber quantity was 35… 80%, strongly dissociated anionic substances as benzoic acid being adsorbed only to a low degree and weakly cationic and undissociated substances being adsorbed well. Within a homologous series adsorption increases with the molar mass until the pore diameter will become too small for the taking up of substances. Under dynamic conditions (filtration technology) an elimination of 90… 100% can be expected. As a whole, the adsorption on activated carbon was better in all cases than the adsorption on the polymers. The desorption for the regeneration of the polymers is the more difficult the better the substance contained is adsorbed. By repeated loading and regeneration only a slight influence on the adsorption and desorption of a substance was found.     

Removal of NO3– from Drinking Water by Electrocoagulation – An Alternate Approach

The present study provides an electrocoagulation method, for the removal of NO₃^– from drinking water using magnesium as the anode and cathode. The experiments are carried out as a function of pH, temperature, and current density. The results show that the maximum removal efficiency of 95.8% was achieved at a current density of 0.25 A/dm², at a pH of 7.0. The adsorption of NO₃^– preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of the adsorbed molecules. The adsorption process follows a second‐order kinetics model. Thermodynamic studies show that the adsorption was exothermic and spontaneous in nature.     

Enhancement of Carbon Dioxide Capture by Amine‐Functionalized Multi‐Walled Carbon Nanotube

In this study, crude multi‐walled carbon nanotubes (MWCNT) was functionalized by a two‐step process; first using strong mixed acids (H₂SO₄/HNO₃) and then treatment with 1,3‐phenylenediamine (mPDA). The equilibrium adsorption of CO₂ on pristine MWCNT and amine functionalized MWCNT (MWCNT‐NH₂) were investigated. Experiments were preformed via application of volumetric method in a dual sorption vessel at temperature range of 298–318 K and pressures up to 40 bars. The results obtained indicated that the equilibrium uptake of CO₂ increased after functionalizing of MWCNT. The increase in CO₂ capture by MWCNT‐NH₂ was attributed to the existence of great affinity between CO₂ molecules and amine sites on this adsorbent at low pressures. The experimental data were analyzed by means of Freundlich and Langmuir adsorption isotherm models. The data obtained revealed a fast kinetics for the adsorption of CO₂ in which most of adsorption occurred at initial period of adsorption experiments. This renders MWCNT as a suitable adsorbent for practical applications. Values of isosteric heat of adsorption were evaluated based on Clausius–Clapeyron equation. The results demonstrated that both chemisorption and physisorption played important role in CO₂ adsorption on MWCNT‐NH₂, whereas the physisorption process was dominant for CO₂ adsorption on MWCNT.     

Evaluation of Two Low‐Cost–High‐Performance Adsorbent Materials in the Waste‐to‐Product Approach for the Removal of Pesticides from Drinking Water

This study evaluates the performance of two low cost and high performance adsorption materials, i.e., activated carbon produced from two natural waste products: Bamboo and coconut shell, in the removal of three pesticides from drinking water sources. Due to the fact that bamboo and coconut shell are abundant and inexpensive materials in many parts of the world, they respond to the “low‐cost” aspect. The adsorption capacities of two local adsorbents have been compared with commercial activated carbon to explore their potential to respond to the “high quality” aspect. Two pesticides were selected, namely dieldrin and chlorpyrifos, because they are commonly used in agriculture activities, and may remain in high concentrations in surface water used as drinking water sources. The results indicate that the adsorption of pesticides on activated carbons is influenced by physico‐chemical properties of the activated carbon and the pesticides such as the presence of an aromatic ring, and their molar mass. The activated carbon produced from bamboo can be employed as low‐cost and high performance adsorbent, alternative to commercial activated carbon for the removal of pesticides during drinking water production. The performance of activated carbon from bamboo was better due to its relatively large macroporosity and planar surface. The effect of adsorbent and pesticide characteristics on the performance was derived from batch experiments in which the adsorption behavior was studied on the basis of Freundlich isotherms.     

Studies on the Removal of Iron from Drinking Water by Electrocoagulation – A Clean Process

The present study describes an electrocoagulation process for the removal of iron from drinking water using magnesium as the anode and galvanized iron as the cathode. Experiments were carried out as a function of pH, temperature and current density. The adsorption capacity was evaluated using both the Langmuir and the Freundlich isotherm models. The results show that the maximum removal efficiency of 98.4% was achieved at a current density of 0.06 A dm^–2, at a pH of 6.0. The adsorption of iron was better explained by fitting the Langmuir adsorption isotherm, which suggests a monolayer coverage of adsorbed molecules. The adsorption process followed a second‐order kinetics model. Temperature studies showed that adsorption was endothermic and spontaneous in nature.     

Zur Konzentrationsabhängigkeit der Sorption von Co(II) an Titanschwamm

The sorption of Co(II) from aqueous solutions on granulated titanium dioxide was investigated in dependence on pH-value (pH = 6 … 10) and solution concentration (c_L = 10^?7 … 10^?2 mol/kg) at 83 °C. The precipitation in the solution occurred at high pH-values and solution concentrations was determined by control experiments without the adsorber. The adsorption isotherms are S-shaped. This can be interpreted as transition from chemisorption at the basic material to surface precipitation.