Search

The possibility of synthetic silicone sorbent PSTU-3F using for the adsorption removal of mercury from an aqueous solution has been studied. The dependence of mercury adsorption on the pH of the solution, the amount of the adsorbent and the duration of the contact of the solution with the adsorbent was investigated. It was shown that the amount of adsorption is the higher, the higher the acidity of the solution. It has been established that the mercury adsorption process on the PSTU-3F sorbent is described by the Freundlich equation.

[ES] La presente tesis doctoral tiene como objetivo la utilidad de restos vegetales de origen agrícola y no agrícola para la eliminación de fósforo de las aguas residuales, y con ello reducir la eutroficación del lago de l'Albufera de Valencia, en el este de España. Bajo el concepto de Economía Circular, la cual se basa en reducir la entrada de materiales y la generación de desechos en sistemas productivos, los restos vegetales son utilizados para la producción de energía renovable en plantas de biomasa, una vez incinerados en estas plantas los restos vegetales pasan a ser un residuo, la ceniza. Se han estudiado las cenizas de materiales vegetales agrícolas como es la paja de arroz y los restos de podas de vegetación invasora como es el carrizo, ambos procedentes del Parque Natural de l'Albulfera de Valencia. Además, se han utilizado cenizas de una planta de biomasa de la comarca del Rincón de Ademuz, en el interior de la provincia de Valencia, alimentada con restos vegetales agrícolas como son la paja de trigo, paja de cebada y madera de plantaciones de paulonia cultivadas para la producción de bioenergía. Para poder reducir la concentración de fósforo del agua, se ha seleccionado el proceso que hoy en día más posibilidades tiene de ser un sistema de bajo coste y alta eficiencia como es la adsorción. Mediante las isotermas de adsorción de Langmuir, Freundlich y Tempkin se han determinado las capacidades de adsorción de fósforo, llegando a una reducción de fosforo de hasta casi del 99%, siendo la isoterma de Langmuir la que mejor ajuste posee al proceso de adsorción de fósforo. Por último, el residuo producido en el proceso de depuración, que es la ceniza con alta concentración de fosforo, puede ser utilizada para la fertilización de campos agrícolas., [CAT] La present tesi doctoral té com a objectiu la utilitat de restes vegetals d'origen agrícola i no agrícola per a l'eliminació de fòsfor de les aigües residuals, i amb això reduir l'eutrofització del llac de l'Albufera de València, en l'est d'Espanya. Sota el concepte d'Economia Circular, la qual es basa a reduir l'entrada de materials i la generació de deixalles en sistemes productius, les restes vegetals són utilitzats per a la producció d'energia renovable en plantes de biomassa, una vegada incinerats en aquestes plantes les restes vegetals passen a ser un residu, la cendra. S'han estudiat les cendres de materials vegetals agrícoles com és la palla d'arròs i les restes de podes de vegetació invasora com és el canyís, tots dos procedents del Parc Natural de l'Albulfera de València. A més, s'han utilitzat cendres d'una planta de biomassa de la comarca del Racó d'Ademús, a l'interior de la província de València, alimentada amb restes vegetals agrícoles com són la palla de blat, palla d'ordi i fusta de plantacions de paulonia cultivades per a la producció de bioenergia. Per a poder reduir la concentració de fòsfor de l'aigua, s'ha seleccionat el procés que hui dia més possibilitats té de ser un sistema de baix cost i alta eficiència com és l'adsorció. Mitjançant les isotermes d'adsorció de Langmuir, Freundlich i Tempkin s'han determinat les capacitats d'adsorció de fòsfor, arribant a una reducció de fòsfor de fins a quasi del 99%, sent la isoterma de Langmuir la que millor ajust posseeix al procés d'adsorció de fòsfor. Finalment, el residu produït en el procés de depuració, que és la cendra amb alta concentració de fòsfor, pot ser utilitzada per a la fertilització de camps agrícoles., [EN] The objective of this doctoral thesis is the use of vegetable remains of agricultural and non-agricultural origin for the elimination of phosphorus from wastewater, and thereby reduce the eutrophication of the lagoon of l'Albufera de Valencia, in eastern Spain. Under the concept of Circular Economy, which is based on reducing the entry of materials and the generation of waste in production systems, plant remains are used for the production of renewable energy in biomass plants, once the remains are incinerated in these plants. Vegetables become a residue, the ash. The ashes of agricultural plant materials such as rice straw and the remnants of pruning of invasive vegetation such as reed have been studied, both from the Natural Park of l'Albulfera de Valencia. In addition, ashes from a biomass plant from the Rincón de Ademuz region, in the interior of the province of Valencia, have been used, fed with agricultural plant remains such as wheat straw, barley straw and wood from cultivated paulownia plantations for the bioenergy production. In order to reduce the phosphorus concentration of the water, the process that today has the most possibilities of being a low-cost and high-efficiency system, such as adsorption, has been selected. By means of the adsorption isotherms of Langmuir, Freundlich and Tempkin, the phosphorus adsorption capacities have been determined, reaching a reduction of phosphorus of up to almost 99%, being the Langmuir isotherm the one that best fits the phosphorus adsorption process. Finally, the residue produced in the purification process, which is ash with a high concentration of phosphorus, can be used for the fertilization of agricultural fields.

Remazol Brilliant Blue dye is a noxious dyes, so the snail shell powder was used as a adsorbent surface because of its high efficiency to remove the remazol brilliant blue dye from aqueous solutions where the removal percent was (99.09%). Also, the factors affect the efficiency of adsorption (equilibrium time, adsorbent weight, PH, ionic strength, temperature and using "Langmuir, Freundlich and Temkin" modelels were studied. The experimental data of isotherm showed that it is in good agreement with the freundlich and temkin equation it to take the form (S-curve) according to the Giles classification, and it does not agree with the Langmuir equation. The thermodynamic functions (ΔS, ΔH, ΔG) were calculated and explained in the mean of the chemical structure of the adsorbant.

WOS: 000472243500012, PubMed ID: 31121425, The UO22+ biosorption properties of a lichen, Evernia prunasui, from aqueous solutions were investigated. The widely occurring lichen samples were collected from the forest in Bilecik-Turkey. The UO22+ biosorption onto lichen was characterized by FT-IR and SEM-EDX analysis techniques before and after biosorption. The effects of the solution pH, biosorbent dosage, UO22+ concentration, contact time, and temperature on UO22+ biosorption on lichen sample were studied by using the batch method. The isotherm experimental data were described using isotherm models of Langmuir, Freundlich and Dubinin Radushkevich. The maximum UO22+ biosorption capacity of the lichen sample was estimated by the Langmuir equation to be 0.270 mol kg(-1). The adsorption energy from the Dubin Radushkevich model was found to be 8.24 kJ mol(-1). Kinetic data determined that the biosorption was best described by the pseudo-second-order kinetic model. Thermodynamic findings showed that the biosorption process was endothermic, entropy increased and spontaneous. In conclusion, the lichen appears to be a promising biosorbent for the removal of UO22+ ions from aqueous solutions because of high biosorption capacity, easy usability, low cost, and high reusability performance., Cumhuriyet University Scientific Research Projects Commission, The present study was partly supported by Cumhuriyet University Scientific Research Projects Commission. The authors have declared no conflict of interest.

Ammonia which is bound to the adsorbent can interfere adsorption process, so that release the compound can be done by desorption process. This research intends to know appropriate equilibrium models to determine maximum capacity of active carbon for desorption ammonia. The method which used in desorption process are Langmuir and Freundlich isotherm models. The research was performed with variation of active carbon mass and variation of contact time. The concentration of ammonia on the desorption process was determined using spectrophotometer at λ 420 nm. The experiment result showed that the more the active carbon dosage is used, the more the concentration of ammonia is increased. Optimum contact time during 7 hours with desorption percentage 94-96%. This research of ammonia desorption by active carbon followed the Langmuir equilibrium model R2 0.954 and Freundlich equilibrium model R2 0.952. The equilibrium equation is used Langmuir equation y = -0.015x + 3.185, maximum desorption capacity is 66.67 mg/g.

Batch isotherm studies were carried out on a laboratory scale: (i) to investigate the effectiveness to remove lead of two wastes (olive stone (OS) and olive tree pruning (OTP)), untreated and chemically treated; and (ii) to examine the applicability of various adsorption isotherms to fit the experimental data. Results from tests were analyzed using seven equilibrium isotherm correlations (Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, Redlich–Peterson, Sips, and Toth equations). The sum of the squares of the errors was determined for each isotherm and the Langmuir equation provided the best fit. Chemical treatments increased the biosorption properties of these materials. The maximum biosorption capacities were: 6.33, 49.13, 14.83, and 38.93 mg g−1 for untreated OS, HNO3-OS, H2SO4-OS, and NaOH-OS, respectively, and 26.72, 86.40, 72.78, and 123.80 mg g−1 for untreated OTP, HNO3-OTP, H2SO4-OTP, and NaOH-OTP, respectively. Finally, the loss of mass for each waste (13.9, 14.3, and 36.8% for HNO3-OS, H2SO4-OS, and NaOH-OS and 35.1, 27.5, and 46.7% for HNO3-OTP, H2SO4-OTP, and NaOH-OTP, respectively) was taken into account and an effectiveness coefficient was determined for each adsorbent material.

Pollutions of livestock and poultry breeding to the environment have evolved into a serious social problem, while phosphorus is a non-renewable resource. This study aims to not only remove the phosphorus in bovine urine wastewater effectively, but also make it recyclable and reduce the load of the follow-up sewage disposal. Choosing the diatomite as the adsorption material, its adsorption effects and the influence factors of diatomite were investigated by static adsorption method, and the adsorption isothermal curves studied. The results showed that the best adsorption condition was as follows, i.e.,taking 50mL bovine urine wastewater with TP 45.67mg/L, when the diatomite dosage was 3.0g, the pH was 7.0, the adsorption time was at 6.0h with the temperature of 30, TP concentrations could be reduced to 9.86mg/L and total phosphorus removal rate reached at 78.41%. Freundlich equation was better than Langmuir equation in describing the behaviour of adsorption phosphorus on diatomite. It is believed that diatomite is feasible to be used as adsorption agent for phosphorus removal from bovine urine wastewater and this promotes the potential of diatomite being used as sewage treatment materials.

The use of waste of natural rubber latex with banana sheats powder filler to serve as a more useful product that is used as adsorbent of oil. The process begins with drying the adsorbent manufacture banana and polished up to 100 mesh size. Then the banana powder mixed with waste latex with variations of 10 and 20% (w / w). The analysis of the ability of the adsorbent adsorption isotherms using the Langmuir equation and Freundlich isotherm equation. Research carried out by the batch process and the use of lubricating oil as the adsorbate. The results obtained showed the addition of banana powder as filler waste adsorbent adsorption of latex increases the ability of the oil adsorbent. The conclusion of the analysis showed an increase in the number of characteristics adsroben banana powder can enhance the adsorption of adsorbent. Keywords : n atur a l rubber latex wast e, b anana sheaths powder, a dsorbent oil, a dsorption ability

The adsorption behaviors of V(V) and Mo(VI) on the collagen fiber immobilized bayberry tannin (IBT), a new kind of adsorption, were investigated. It was found that at 323K, pH=2.0, the adsorption capacities of V(V) on 0.100g adsorbent was 1.03mmol/g in 100ml of 1.960mmol/L V(V) solution, and that of Mo(VI) was 0.86mmol/g at 323K, pH=4.0, with 100ml of 1.042 mmol/L Mo(VI) solution. The effect of pH on the adsorption capacity of V(V) and Mo(VI) was conspicuous. The adsorption capacity of Mo(VI) decreased with pH increasing, and the maximal adsorption capacity of V(V) was observed at pH4.0. Langmuir equation was used for the description of adsorption isotherms of V(V), while Freundlich equation could be well described that of Mo(VI). The adsorption kinetics of V(V) and Mo(VI) can be well described by the pseudo-second-order-rate model and the adsorption capacities calculated by this model are very close to those experimentally determined. The adsorbent can be regenerated by using 0.1mol/L HCl and 0.02mol/L EDTA in tune as desorption agent after the adsorption of V(V) and Mo(VI). In the desorption process V(V) and Mo(VI) were utilized respectively. These facts implies that the adsorbent can be used for the separation of V(V) and Mo(VI) in aqueous.

In order to investigate the characterizations of skin adsorption material (SAD) prepared from skin of corn stalks by High Boiling Solvent treatment, neutral proteinase and maltogenic amylase were selected as adsorbate to assess its potential applicability for enzyme immobilization. The structure of SAD and Skin were compared by FT-IR and XRD. The characterizations of the adsorption of the different enzymes onto SAD were studied. The isotherm of the maltogenic amylase was found to be linear with the Freundlich equation, and proteinase was found to be linear with the Langmuir equation in the studied concentration range. SAD could be applied the bio-active material and Skin to prepare SAD.

Biosorption behavior and mechanism of an exopolysaccharide (EPS) secreted by a psychrotolerant bacterium Pseudoalteromonas sp. Bsi20310 isolated from Antarctic sea-ice, for lead(II) from synthetic wastewater were studied in this paper. Effects of salinity, pH and dosage of Bsi20310 EPS on biosorption characteristics for lead(II) were evaluated by batch biosorption tests. The results indicated that Bsi20310 EPS presented better biosorption performance for lead(II) in salt water than in salt-free water. The equilibrium biosorption isotherms fitted well to both Langmuir and Freundlich isotherm models. Theoretical maximum biosorption capacity of 191.90 mg g−1 calculated according to Langmuir equation indicated that Bsi20310 EPS had a high biosorption capacity for lead(II). The kinetics of lead(II) biosorption onto Bsi20310 EPS could be better described by pseudo-second-order model than pseudo-first-order both in salt-free water and in salt water. External surface biosorption was the major biosorption...

The potential of removing Bomaplex Red CR-L dye from electro coagulation sludge has been investigated for different Bomaplex Red CR-L concentrations with varying adsorbent amount, temperature, pH and stirrer speed. Removal of Bomaplex Red CR-L is found to be high at lower pH values. The maximum adsorption of the dye has been achieved in aqueous solutions using 0.5 g of calcinated sludge from electro coagulation at a pH of 2.0 within 20 min. The Langmuir and Freundlich isotherm models were tested and it was found that the Langmuir equation was fitted better than the Freundlich equation. Maximum adsorption capacity ( q m ) was calculated as 192.31 mg g − 1 at 333 K. In addition, the adsorption data obtained at various temperatures were successfully applied to pseudo first-order, pseudo second-order and intraparticle diffusion models. The rates of adsorption were found to conform to pseudo second-order kinetics with good correlation ( R 2 ≥ 0.9997). This study showed that calcinated the sludge from electrocoagulation has a highly adsorbent capacity.

Reactions of copper with kaolin are important in determining copper fate in the environment. Adsorption characteristics of Cu by the kaolin from Suzhou, China were investigated at varying Cu concentrations (0 to 100 mg/l), pH values (approximately 2 to 11) and temperature (25, 40 and 50 °C). Cu adsorption by the kaolin was well described by the Langmuir and Freundlich adsorption equations. The kaolin did not exhibit the adsorption maximum, 666.67 mg/kg, as determined by the linearized form of the Langmuir equation. The k d values decreased exponentially with increasing initial Cu concentrations in the solution. A unit increase in pH resulted in approximately 8.47, 9.61 and 10.82% increase in Cu adsorption by the kaolin at the initial Cu concentration 5, 50, 100 mg/l, respectively. The pH 50 values increase with increasing initial Cu concentration. Desorption of Cu was well described by the linear model ( y = 0.0917 x + 0.7136) with correlation coefficient R 2 = 0.9994. Most of the adsorbed Cu is nonspecific adsorption; the mobility of Cu in the kaolin from Suzhou, China is high under low pH conditions.

The retention of pendimethalin by humic acids (HAs) from different farm wastes and from soils in various management systems was studied at 20 and 40°C. The magnitude of pendimethalin retained varied from 19.50–71.00 and 20.50–80.00 μM g −1 at 20°C on HAs from farm wastes and soils, respectively, which decreased with a rise in temperature. Pendimethalin retention followed the order: Soil HAs > Farm waste HAs. The highly significant values of R 2 suggested the excellent fitness of the Freundlich (0.965**–0.996**) and Langmuir (0.943**–0.986**) isotherms for pendimethalin retention. The values of the ‘k’ and ‘n’ retention parameters of the Freundlich isotherm and the ‘K’ and ‘b’ parameters of the Langmuir equation confirmed the relatively higher capacity of soil HAs to retain pendimethalin.

Summary In this paper I discuss sorption curves: choosing them, fitting them, and interpreting them. The Langmuir equation is not appropriate for reaction of ions with soil. Despite some disadvantages, the Freundlich equation is the best simple equation. Fitting sorption equations causes statistical difficulties because sorption is usually calculated from the change in concentration. The two variables are therefore not independent. If this is ignored, the errors in the coefficients of the fitted curves will be small, but there will be larger errors in the measures of goodness of fit and tests of significance will not be valid. If mild but nevertheless adequate mixing of soil and solution are chosen, sorption and desorption will be the opposites of each other. We can therefore learn much about the rates of desorption by studying the rates of sorption. If a sink is used to capture desorbed nutrients, the potential rate of desorption will be underestimated, as no sink can instantly and completely remove all the nutrients from solution. Especially with phosphate, continuing reaction makes the surface potential more negative. This means that re-application is made to a soil of smaller buffering capacity. This effect has been insufficiently studied. It influences both the response to further applications, and the ability of soil to store nutrients.

Silicate adsorption in eight paddy soils developed from four different parent materials in Guangdong Province, China was examined to obtain fundamental knowledge of silicate adsorption to improve the efficacy of silicate fertilizer use in these areas. A correlation analysis showed that silicate adsorption did not obey the Langmuir equation (r = −0.664−0.301) but did obey the Freundlich and Temkin equations (P ≤ 0.01, r = 0.885–0.990). When the equilibrium silicate concentration (Ci) was less than 45 mg SiO2 kg−1, the adsorption capacity was in the following decreasing order of paddy soils: basalt-derived > Pearl River Delta sediment-derived > granite-derived > sand-shale-derived. Stepwise regression and path analysis showed that for the investigated paddy soils amorphous MnO and Al2O3 were the two most important materials that affected silicate adsorption. Moreover, as Ci increased, amorphous Al2O3 tended to play a more important role in silicate adsorption, while the effects of amorphous MnO on silicate adsorption tended to decrease.

The adsorption of the water-soluble Reactive dye Brilliant Blue X-BR onto three different types of resins was investigated. The study focused on the static equilibrium adsorption behaviours and other factors influencing the adsorption process. The three resins exhibited different adsorption behaviours and mechanisms for the adsorption of X-BR from aqueous solution. The adsorption isotherms associated with the acrylic ester resin YWB-50 could be well fitted by the Langmuir equation, while those of the resins NDA-150 and D-301 could be well fitted by the Freundlich equation. The adsorption dynamics and desorption process were also investigated as a means of further exploring the difference between the adsorption behaviours and mechanisms on the three resin types.

The adsorption of 6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (atrazine) on a heat treated kerolite sample at 600 degrees C (K-600) from pure water solution at 10 degrees C, 25 degrees C and 40 degrees C has been studied. The influence of the presence of 0.1 M KCl in the medium was also investigated for a better understanding of variables affecting the adsorption of this herbicide. The experimental adsorption data points were fitted to the Langmuir equation in order to calculate the adsorption capacities (Xm) of the samples; Xm values range from 2.3x10(3) mg kg-1 (pure water solution at 40 degrees C) up to 15.2x10(3) mg kg-1 (0.1 M KCl solution at 10 degrees C). The adsorption data were also fitted to the Freundlich equation in order to clarify the influence of the presence of 0.1 M KCl on atrazine adsorption. The parameter K10 obtained from this equation (adsorption capacity at an equilibrium solution concentration of atrazine equal to 10 mg l-1) shows clearly that the presence of 0.1 M KCl in the medium tends to increase the adsorption of atrazine in the range of temperature studied. The adsorption experiment also showed that the lower temperature, the more effective the adsorption of atrazine from both, pure water and 0.1 M KCl solutions. The values of the removal efficiency (R) obtained ranged from 39% at 40 degrees C (pure water solution) up to 93% at 10 degrees C (0.1 M KCl solution).

A new sorbent (rice bran) for removing Cu 2+ from aqueous solution has been investigated. The experimental results were fitted to the Langmuir, Freundlich, Temkin and Redlich–Peterson isotherms to obtain the characteristic parameters of each model. Langmuir, Temkin and Redlich–Peterson isotherms were found to represent the measured sorption data. The maximum sorption capacity of Cu 2+ on the rice bran was 33.58 mg/g according to the evaluation of using the Langmuir equation.

Inverse gas chromatography (IGC) has been used to evaluate the adsorption parameters (Δ H , Δ S and Δ G ) of some n -alkanes ( n -C 5 to n -C 8 ) on 3A, 4A and 5A zeolites. The adsorption parameters of the probes on 4A were determined in the finite concentration region, and those on 3A and 5A were determined in the infinite dilution region. It was found that the adsorption isotherms for 4A conform with the Langmuir equation and the adsorption parameters increase linearly with increasing carbon number of the probes for 3A, 4A and 5A. Thermodynamic compensation effect between the adsorption enthalpy and entropy was observed. Also, heats of adsorption for 3A were found to be higher than those for 5A.

Quantification of soil processes, such as adsorption, is needed for predicting the fate of agricultural chemicals in soils. Adsorption is affected by soil properties, which vary with depth. We conducted a laboratory study to determine the influence of soil depth on the adsorption of an organic solute (atrazine) in both allophanic and non‐allophanic soils, and an inorganic solute (phosphate) in two non‐allophanic soils. Adsorption isotherms of atrazine and phosphate were determined using 14C‐labelled atrazine and KH2PO4, respectively, in batch equilibrium. The adsorption isotherms for atrazine were almost linear, and adequately described by the Freundlich equation. For phosphate the adsorption isotherms exhibited substantially more curvature and were best described by the Langmuir equation for one of the soils. Generally, adsorption of both solutes decreased with depth. While atrazine adsorption appeared related to such factors as percentage clay content, total C, cation exchange capacity (CEC), a...

The traditional Freundlich equation used to correlate direct dye sorption on cellulose is compared to the Langmuir equation for correlating the same data. Results taken from six different direct dyes are presented that show a much better correlation of the data is obtained with the Langmuir equation indicating that the interaction of dyes with the substrate is rather specific. The specific nature of the sorption process is compared to acid dye sorption on aminised cotton which also is shown to be Langmuir type. Explanation of the sorption of mixtures of direct dyes is also discussed as being better interpreted in terms of the Langmuir sorption.

In this study, bauxite and modified bauxite /polymer, which were prepared as an adsorbent surfaces to adsorption of the tetracycline from aqueous solutions. A series of adsorption experiments were conducted to determine the equilibrium time and temperature effect on the adsorption process. The results showed that adsorption was agreed with the Freundlich equation model for the surface of the bauxite. As for the modified bauxite surface, the results were consistent with the Langmuir equation model. The values of the basic thermodynamic functions of the adsorption process were calculated, so the process of adsorption was founded spontaneous and endothermi

A study on the sorption of monocrotophos and parathion-methyl on Yellow River’s sediments was performed. The influence of some factors, such as pH value and ionic strength, on the sorption was investigated and first order kinetics mode for the sorption of monocrophos was shown. Freundlich isotherm was suggested as the most appropriate type for monocrophos and parathion-methyl. But the sorption isotherms of monocrotophos and parathion-methyl are also in conformity with Langmuir equation. Both partition and adsorption occur to the sorption of monocrophos to Yellow River’s sediments, but partition is the predominant for that of parathion-methyl.

The Langmuir adsorption isotherm equation is extended to include a third parameter. The extended Langmuir model is then compared with the Langmuir, the Langmuir–Freundlich and the Toth models in their ability to fit experimental data.

Se realizaron isotermas de adsorción para determinar el equilibrio de distribución de plomo en los suelos del área de influencia de la mina La Vetica, ubicada en el distrito minero de Buenos Aires en el Departamento del Cauca, con el fin de determinar su capacidad de adsorción y retención. Se evaluaron dos modelos de adsorción: el primero asume que el fenómeno se presenta en la primera capa superficial (superficie homogénea) tal como la describe los modelos de Langmuir, Dubinin-Radushkevich y Frumkin; y el segundo asume que la adsorción se da en multicapas (superficie heterogénea), como la describe las isotermas de Freundlich, Harkins-Jura y Temkin. La isoterma de Langmuir fue el modelo que mejor se ajustó al proceso de adsorción; la linealización de la ecuación de Langmuir arrojó una capacidad máxima de retención de plomo en el suelo, Qo, de 6,42 mg/g. El valor de la energía de adsorción, E, encontrada, mediante la ecuación de Dubini-Radushkevich, fue de 15,81 kj/mol, valor que se halla en el rango de enlaces tipo Van der Waals, confirmando que la adsorción ocurre mediante interacciones débiles.

Потенційно небезпечними є сховища та майданчики для зберігання шламів гальванічного виробництва ряду промислових підприємств м.Суми (АТ Сумське машинобудівне науково-виробниче об’єднання ім. Фрунзе, АТ «Насосенергомаш»). Важкі метали, що містяться в цих гальваношламах, потрапляють в грунтові води, вимиваються зі стічними водами і потрапляють в природні водні об’єкти. Акумуляція цих сполук в організмі негативно позначається на життєво важливих функціях гідробіонтів. Для вивчення застосування широкого спектру різних місцевих природних мінералів в процесах очищування забруднених іонами Zn2+ стоків досліджували глинисті утворення з різних регіонів Сумської області. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/31712

The binding capacity of Cd to the sediment particles determines the potential of Cd release from the sediments. An experiment was performed to evaluate the adsorption of Cd by contaminated sediments collected from three different locations in Hong Kong, i.e. Kwun Tong, North Point and Nam Tam Wan, having different degrees of pollution. Langmuir and Freundlich equations were used to evaluate the adsorption of Cd by the sediments. Adsorption isotherms obtained from the Freudlich and Langmuir equations were generally linear and the adsorption of Cd by the sediments was significantly correlated with the adsorption maximum and binding energy constant of the Langmuir equation, and equilibrium partition constant of the Freundlich equation. All sediments had a high Cd adsorption capacity and the highly organic contaminated sediments from Kwun Tong had the highest adsorption capacity of 24,272 mg kg‐1 at pH8. The adsorption of Cd for all sediments increased with a rise in pH of the equilibrium solution and the tot...

Zinc (Zn) sorption by six Alabama soils, virgin and cultivated was studied. Sorption data was collected at 10° and 30°C and plotted according to the Langmuir, Freundlich, and BET equations. The differential isosteric heats of sorption, AH, were used to aid in the interpretation of the data. The high pH soils sorbed more Zn compared to acid soils. Zinc sorption increased with an increase in temperature indicating that the sorption process was an endothermic reaction. All of the soils gave curvilinear lines when plotted according to the Freundlich equation. The same was true for the Langmuir equation except for the two high pH soils which gave one straight line. Deviation from the ideal Langmuir model was interpreted to be due to the variation in heat of sorption, AH, due to surface heterogeneity. However, the BET equation gave the best fit for the data, yielding one straight line for all soils. The Langmuir sorption maximum, b, was correlated with some selected soil properties. The results indicat...

In a previous work, the author gave an adsorption isotherm for the general case of single-site heterovalent exchange and simpler approximate equations having linear forms involving the same plot used for the Langmuir isotherm. The present work gives a substantiation of these equations by calculations involving some potential practical examples. It also extends the equations to the case of two-site (multisite) heterovalent exchange and considers the evaluation of the different ion exchange parameters. Further discussion is given on the hazards of the application of the Langmuir equation to ion exchange reactions. For homovalent exchange, instead of the Langmuir isotherm, use of the single-site isotherm or two-site isotherm of Boyd et al., as treated in our previous work, is recommended. This isotherm is graphically represented by the same plot used for the Langmuir isotherm. It is more instructive, avoids confusion and allows for equilibrium constant calculations. In the case of heterovalent exchange, the equations given in the previous work for single-site adsorbents and in the present work for two-site (multisite) ones should invariably be used to obtain correct results.

Equilibrium isotherms for adsorption of BSA on DEAE-dextran have been determined experimentally. They were little affected by the initial concentration of BSA but were considerably affected by pH. They were correlated by the Langmuir equation when pH ≥ 5.05 and by the Freundlich equation at pH 4.8 (≈ pI). The maximum amounts of inorganic anion exchanged for BSA were 1 and 0.4% of the exchange capacity of the ion exchanger at pH 6.9 and 4.8, respectively. When NaCl coexisted in the solution, the shape of the isotherm was similar to the Langmuir isotherm but was shifted to the right. When the concentration of NaCl was 200 mol/m3, BSA was not adsorbed on the resin. When BSA was dissolved in pure water, the saturation capacity of BSA on HPO4 2− -form resin was about 3.5 times larger than that with buffer (pH 6.9). The amount of BSA adsorbed on univalent-form resin decreased when the liquid-phase equilibrium concentration of BSA was increased.

Efficiencies of synthetic adsorbents and attapulgites in bleaching alkali-refined rapeseed and soybean oils ranged from 13–53% and 93–97%, respectively. The Freundlich equation was more applicable than the Langmuir equation to the experimental adsorption isotherms of β-carotene on attapulgites. Bleaching with attapulgites reduced tocopherols by 12.5–29.5% in rapeseed oil and by 18.9–44.8% in soybean oil. Cosmetic-grade attapulgite was superior to the others in bleaching efficiency, equilibrium amount adsorbed and removal of free fatty acids.