Freundlich Sorption Isotherm Research Articles

Correlating shale geochemistry with metal sorption: influence of kaolinite content

ABSTRACT Argillaceous rocks constituting clay fractions are potential host rock candidates for isolation of radioactive waste in underground repositories. The present study aims at characterization of two argillaceous rocks (shales) from different geological settings (surface and subsurface localities) and investigation of their cesium (Cs) sorption behaviour. The shales were characterized using various analytical techniques to evaluate the textural attributes, mineralogical constituents and surface properties. The major mineralogical constituent of the surface and subsurface shale was quartz (62%) and kaolinite (56%), respectively. The abundance of smectite and illite in both the shales was comparable. Fluorescence and UV-Vis spectra confirmed the presence of polyaromatic hydrocarbons (PAHs) in the subsurface shale. The subsurface shale demonstrated higher Cs retention (17 mg g−1) than the surface shale (12 mg g−1) due to higher kaolinite content. Surface analysis of the shale samples revealed involvement of ion exchange mechanism in Cs uptake. The agreement of experimental results with Freundlich sorption isotherm suggests the heterogenous nature of the shales with multiple sorption sites. The correlation of geochemistry (especially the kaolinite content) for both the shales with Cs sorption is clearly highlighted in the present studies. The present investigation implies the applicability of the studied shales for waste management applications.

Chemical synthesis of ZnO, CuO, MnO and FeO Nano adsorbent and their application in anionic reactive blue turquoise 71 dye (RB-71 dye) and real effluents remediation: Batch adsorption and column studies

Industrial dye production chemicals contribute significantly to environmental pollution. This study explores the use of nanotechnology, specifically nano fertilizers and adsorption technology, for efficient removal of synthetic anionic dyes and enhancing agricultural production. Nano adsorbents (MnO, FeO, ZnO, and CuO) were generated using the co-precipitation method. Optimal conditions for Manganese oxide (MnO) were pH 2 (33.2 mg/g), dosage 0.01 g/50 mL, and adsorption capacity 77.2 mg/g. FeO optimal conditions were pH 2 (21.5 mg/g), dosage 0.01 g/50 mL, and qe 40.5 mg/g. CuO optimal conditions were pH 2 (28.2 mg/g), dosage 0.01 g/50 mL, and qe 71.3 mg/g. ZnO optimal conditions were pH 2 (25.4 mg/g), dosage 0.01 g/50 mL, and qe 64.2 mg/g. Pseudo 1st order and Freundlich sorption isotherms were best-fit models. Endothermic reactions were observed, indicating the sorption process’s nature and feasibility. Electrolyte concentrations affected the sorption potential. Surfactants/detergents reduced sorption efficiency. 0.5 N NaOH proved most effective for desorption. In column studies, optimal conditions for acidic RB-71 dye sorption were 3 cm bed height, 1.8 mL/min flow rate, and 70 mg/L inlet dye concentration. Metal oxide showed exhibited crystal and polymorphs structure. FT-IR spectra depicted metal-oxide peaks between 400 and 899 cm−1. SEM micrograph reveals a spherical shape with an approximate size of 10–50 μm. The adsorption method’s novelty lies in its easy handling, eco-friendliness, and cost-effectiveness, making it a promising technology for practical-scale application in addressing dye pollution.

Preparation of MgAl-LDHs loaded with blast furnace slag and its removal of Cu(II) and methylene blue from aqueous solution

ABSTRACT Blast furnace slag (BFS) is a kind of waste produced in industrial production, as well as a valuable secondary resource. In this paper, layered double hydroxides composites (BFS/LDHs) were prepared by aqueous polymerization, with industrial waste BFS as modifier and magnesium nitrate, aluminium nitrate, and urea as raw materials. BFS/LDHs have been characterized by using scanning electron microscopy (SEM), fourier infrared spectrometer (FT IR), x-ray diffraction (XRD), and the specific surface area analyser (BET). The adsorption of BFS/LDHs on Cu (II) and methylene blue (MB) was investigated by batch experiments. The results showed that the adsorption capacity of BFS/LDHs to Cu (II) is stronger than that of MB. What’s more, the solid concentration effect was found in the process of sorption kinetics and sorption isotherms. The sorption kinetics curves of Cu (II) and MB on BFS/LDHs were well fitted by the quasi-second-order kinetics under different adsorbent concentrations. Langmuir and Freundlich sorption isotherm models were used to analyse the adsorption. It showed that the adsorption conforms to Langmuir and Freundlich’s adsorption isotherm models. The BFS/LDHs composites have good recycling availability in this adsorption process of Cu (II) and MB, the removal capacity of which was reduced by 16.1% and 3.8% after being recycled for six times, respectively. More importantly, BFS/LDHs composites are not only expected to become a sewage treatment agent, but also to solve the problem of industrial waste treatment, which is a win–win strategy.

Assessment of potential mobility of selected micropollutants in agricultural soils of the Czech Republic using their sorption predicted from soil properties

The sorption of organic contaminants in soils and sediment is a crucial factor affecting their mobility in the vadose zone environment. The Freundlich sorption isotherms were evaluated for eleven micropollutants and eight soils. The highest Freundlich sorption coefficients, KF, were obtained for triclosan (324 ± 153 cm3/nμg1–1/ng−1) followed by sertraline (120 ± 74), venlafaxine (74.3 ± 41.2), telmisartan (33.3 ± 13.6), atorvastatin (8.66 ± 4.78), bisphenol S (8.03 ± 4.87), lamotrigine (6.92 ± 3.02), 2-phenylbenzimidazole-5-sulfonic acid (3.77 ± 2.25), memantine (3.42 ± 1.64), 1-methyl-1H-benzotriazole (2.05 ± 0.99), and valsartan (0.88 ± 0.89). The KF values for the individual compounds were correlated with soil properties. Multiple linear regressions were used to derive equations for predicting the KF values using the soil properties. The first set of equations contained mainly properties with the strongest correlations with the KF values, e.g., a base cation saturation for positively charged compounds or a hydrolytic acidity for negatively charged compounds. The second set of equations contained properties included in the map of agricultural soils of the Czech Republic. These equations always indicated positive correlations with oxidizable organic carbon and clay content. They also included either a negative or positive correlation with pHKCl. A positive correlation with pHKCl was obtained for venlafaxine, memantine, and sertraline, which were mostly positively charged. A negative correlation with pHKCl was obtained for the remaining compounds. The second set of equations, the soil map, and the database of soil properties were used to predict the KF value distributions within the Czech agricultural soils. It resulted in similar KF distributions' patterns for valsartan, lamotrigine, atorvastatin, and telmisartan (with a positive correlation between KF and hydrolytic acidity), which considerably differed from the KF patterns for the other compounds. These maps were used to delineate areas with a leaching potential of the compounds toward groundwater that will serve as a tool for assessing a potential groundwater vulnerability.

Sulfur Fractions, Distribution and Sorption Characteristics in Some Soils of Ogun State, Southwestern Nigeria

ABSTRACT Sulfur (S) fractions, distributions and sorption characteristics of some soils in Ogunstate, Southwestern Nigeria, were evaluated in ten different locations, the area lies with in the Derived Savannah and forest agro-ecological zone. Result showed available, adsorbed, organic and total S ranged from 3.9 to 19.8, 16.3 to 36.6, 214.9 to 412.9 and 248.8 to 446.6 mg kg−1 respectively. Organic S constituted 86.4 to 93.4% of total S. The mean status of available S was slightly above the critical limit of 10 mg kg−1. All fractions of S maintained significant positive correlation (p ≤ .05) with each other and total organic carbon, while available and adsorbed S had significant and negative correlation with soil pH, total nitrogen, available phosphorus and calcium. The S sorption behavior of the soils varied and increased with increase in S concentrations of equilibrium solution. The isotherm model for the ten locations was S-curved type. Sorption data were fitted to Langmuir and Freundlich sorption isotherms. Langmuir equation was best fitted to the S adsorption data in the ten locations except soils from Owode, Odeda and Ikenne. Langmuir and Freundlich parameters (sorption maxima, binding energy and maximum buffering capacity affinity constant and slope) were significantly correlated with some soil properties.

Chromium Removal from Electroplating Wastewater Using Activated Coffee Husk Carbon

Chromium (Cr) is a heavy metal that has a serious environmental pollution problem. Electroplating wastewater contains high level of Cr that surpassed the acceptable environmental discharge standard limit in surface water bodies and causes aquatic ecosystem risks. Various studies have been conducted in Ethiopia on the removal of Cr from various types of wastewater; however, factual studies on the adaptability of cost-effective activated coffee husk carbon for the removal of Cr from electroplating wastewater are lacking. Thus, this study was conducted to evaluate the Cr adsorption efficiency of activated coffee husk carbon from electroplating wastewater at laboratory scale. The activated coffee husk carbon’s pH, electrical conductivity (EC), ash content, moisture content, bulk density, particle size, pore volume, porosity, volatile organic matter, carbon yield, and carbon:nitrogen ratio were determined following standard methods. In the adsorption experiment, adsorbent dosage, agitation speed, contact time, pH, and initial concentration were optimized. Models were used to examine the adsorption isotherms and kinetics. The ability of activated coffee husk carbon to desorb Cr was investigated. The adsorbent functional groups and surface morphology were examined using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM), respectively. Analysis of the physicochemical characteristics of the adsorbent showed that the activated coffee husk carbon has good quality, and thus, playing an important role in metal adsorption. Furthermore, FTIR analysis also confirmed the presence of hydroxyl, carboxyl, and other important functional groups, which promote heavy metal adsorption. The adsorption process optimization revealed 99.65% maximum Cr adsorption efficiency at 120 min contact time, 40 mgL-1 initial concentration, 150 rpm agitation speed, pH 7.0, and 20 gL-1 adsorbent dosages. From the adsorption model studies, Freundlich sorption isotherm and pseudosecond-order models were well fitted with respective [Formula: see text] values of 0.987 and 0.999. A 60% Cr was removed according to desorption studies. In general, due to the ease with which coffee husk can be obtained from coffee processing facilities, its use as an absorbent will be cost-effective and considered as an alternative option in removing Cr metal from wastewaters.

Removal of as(V), Cr(VI) and Cr(III) heavy metal ions from environmental waters using amidoxime and quaternized hydrogels

Acrylonitrile (AN) and 1-vinyl imidazole (VI) based hydrogel was prepared in bulk (macro) dimensions via redox polymerization technique. Afterward, this hydrogel was quaternized (positively charged) and exposed to the amidoximation reaction. The prepared hydrogels (quart-p(AN-co-VI), amid-p(AN-co-VI) and p(VI)) characterized using fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA). Swelling experiments were performed gravimetrically at room temperature in deionized water and different pH solution. Water absorbencies of both amidoximated hydrogels and quaternized hydrogels were founded to be high. Prepared hydrogels were used to remove heavy metal ions such as arsenic(V) (As(V)), Chromium(VI) (Cr(VI)) and Chromium(III) (Cr(III)) from aqueous media. The sorption of As(V), Cr(VI) and Cr(III) metal ions by hydrogels were carried out at different initial metal ion concentrations, different pHs, different times in batch sorption experiments at 25oC. The maximum metal ion sorption capacity by all hydrogels was in the order: As(VI)>Cr(VI)>Cr(III). The maximum sorption capacity for As(VI), Cr(VI) and Cr(III) ions was found to be 598, 303.8 and 4.9 mg g-1 for amid-p(AN-co-VI), respectively. As result of, amidoximated hydrogels have more sorption capacity to metal ions than quaternized hydrogels. Three different kinetic models (pseudo first order, pseudo second order and intraparticle diffusion model) were also used to investigate the sorption mechanisms. Furthermore, the Langmuir and Freundlich sorption isotherms were investigated for these metal ions. As a result of, amidoximation and quaternization of AN and VI based hydrogels have been a promising technique to increase the sorption rate and capacity of hydrogels and are thought to provide great advantages in the removal of metal ions from wastewaters. Especially, among the p(AN-co-VI) modification processes, amidoximation reaction was found to give better results than quaternization reaction. Prepared hydrogels were found to be more selective than Cr(III) versus As(V) and Cr(VI).

REMOVAL OF Cu(II), Cd(II), Co(II), Zn(II), Cr(VI) FROM WASTEWATER BY STABILIZED NANOSCALE ZERO-VALENT IRON

Background. Obtaining sorption materials based on natural raw materials for water purification from pollution by heavy metal ions is an urgent task of our time. Composites with zero-valent iron nanoparticles immobilized on the surface of clay minerals show rather high sorption properties concerning ions of some heavy metals. However, there are only a few proceedings devoted to the physicochemical substantiation of wastewater treatment processes containing a complex mixture of such pollutants. Objective. The purpose of the paper is to study the physicochemical regularities of wastewater treatment from a mixture of ions of heavy metals Cu(II), Cd(II), Co(II), Zn(II), Cr(VI) using stabilized nano dispersed powders of zero-valent iron. Methods. The phase composition and structural-sorption characteristics of palygorskite and composites were studied by X-ray phase analysis and low-temperature adsorption-desorption of nitrogen. The efficiency of removal of metal ions by silicate materials was investigated using the sorption method. The equilibrium concentrations of each of the metals were determined by inductively coupled plasma atomic emission spectrometry. Results. We have investigated the physicochemical features of wastewater treatment containing a complex mixture of heavy metal ions (Cu(II), Cd(II), Zn(II), Co(II), Cr(VI)). The phase composition and structural-sorption properties of stabilized nano dispersed powders of zero-valent iron have been studied. It has been experimentally confirmed that the materials obtained have significantly better sorption properties for the removal of heavy metals from aqueous solutions in comparison with natural palygorskite. Using Freundlich and Langmuir equations sorption isotherms were calculated. Conclusions. It has been established that stabilized nano dispersed powders of zero-valent iron can be successfully used for the purification of wastewater containing a mixture of toxic ions Cu(II), Cd(II), Co(II), Zn(II) and Cr(VI). It is shown that the degree of water purification by the obtained sorbents is 3–5 times higher than that for the unmodified mineral. A significant increase in the values of sorption of anionic forms of Cr(VI), which are difficult to remove from polluted waters by natural ion exchangers, has been determined.

Interaction of pig manure-derived dissolved organic matter with soil affects sorption of sulfadiazine, caffeine and atenolol pharmaceuticals

Pharmaceutically active compounds (PhACs) released into the environment have an adverse impact on the soil and water ecosystem as well as human health. Sorption of PhACs by soils and its potential modification through introduced DOM in the applied animal manure or treated wastewater (TWW) determines the mobility and environmental relevance of PhACs. Sulfadiazine, caffeine and atenolol were selected as target PhACs to investigate their sorption behaviors by five selected arable soils in the absence and presence of pig manure DOM. Sulfadiazine was least sorbed, followed by caffeine and atenolol according to the Freundlich sorption isotherm fit (soil average Kf [μg(1−n) mLn g−1] 4.07, 9.06, 18.92, respectively). The addition of manure DOM (31.34 mg C L−1) decreased the sorption of sulfadiazine and especially of caffeine and atenolol (average Kf 3.04, 6.17, 5.79, respectively). Freundlich sorption isotherms of the PhACs became more nonlinear in the presence of manure DOM (Freundlich exponent n changed from 0.74–1.40 to 0.62–1.12), implying more heterogeneous sorption of PhACs in soil–DOM binary systems. Sorption competition of DOM molecules with sulfadiazine and caffeine mostly contributed to their decreased soil sorption when DOM was present. In contrast, the formation of DOM–atenolol associates in the solution phase caused the largely decreased soil sorption of atenolol in the presence of DOM. It is suggested that DOM concentration (e.g., ≥ 60 mg C L−1) and its interaction with PhACs should be taken into consideration when assessing the environmental impact of land application of animal manure or irrigation with TWW.

PHOSPHORUS SORPTION ISOTHERMS IN SOILS OF THE SEMIARID REGION OF BRAZIL

ABSTRACT The soils of the Semiarid region of Brazil lack studies regarding sorption processes and availability of phosphorus (P). Therefore, the objective of this work was to quantify the sorption of P in ten soils representative of the Semiarid region of Brazil and correlate them with the soil phosphorus storage capacity. The P concentrations in the equilibrium solutions used to model the sorption isotherms were: 0, 5, 10, 15, 20, 30, 40, 55, 70, and 80 mg L-1 for the soils Typic Quartzipsamment (Neossolo Quartzarenico), Typic Hapludox (Latossolo Vermelho Amarelo), Typic Hapludult (Argissolo Vermelho Amarelo), Typic Quartzipsamment (Neossolo Flúvico), and Typic Dystrudept (Cambissolo Haplico); and 0, 10, 15, 25, 40, 55, 80, 100, 130, and 150 mg L-1 for the soils Typic Calciudolls (Chernossolo Rendzico), Typic Dystrudept (Cambissolo Haplico), Typic Dystrudept (Cambissolo Haplico), Typic Hapludult (Argissolo Vermelho Amarelo), and Typic Hapludert (Vertissolo Haplico). The Langmuir and Freundlich sorption isotherms were fitted to non-linear regression models and the values of the model parameters were estimated. The sorption isotherms were adequate to quantify the sorption of P in the soils of the Semiarid region of Brazil, with maximum P sorption capacity varying from 50.4 mg kg-1 to 883.5 mg kg-1. The sorption of P was higher in soils with more clayey textures, alkaline, and rich in iron and calcium, denoting the importance of evaluating the effect of these characteristics on the sorption of P in these soils.

A Study of Using Natural Sorbent to Reduce Iron Cations from Aqueous Solutions.

Iron is an essential trace element, but at high doses, this element may pose a health risk. Wastewater from iron ore mining, steel production, and metal processing, among other heavy metals, also contains high concentrations of iron (Fe3+). The use of sorption on natural materials is a potential alternative to conventional methods for removing iron ions, also because of low cost. The methods presented in this article are based on the study of kinetic properties and the acquisition of adsorption isotherms, which are one of the most important characteristics of adsorption mechanisms. The course of sorption is analyzed according to the Freundlich sorption isotherm model. Isotherm parameters are evaluated using experimental results of ferric cation sorption. The results presented relate to the investigation of natural zeolite-clinoptilolite as a ferric cation sorbent, providing a measurement of the sorption kinetics as well as the observed sorption parameters of iron cations from aqueous media. The optimal time for equilibrium in the adsorption system is determined from the kinetic dependencies. The dependence of the achieved equilibrium concentration on the initial concentration of the solution was also expressed, both graphically and analytically. The new prediction model was compared with the traditional Freundlich model. Finally, adsorption isotherms tested under laboratory conditions for a practical application can be recommended for the preliminary examination of the possible technological use of natural zeolite in the wastewater treatment process.

Modified Crushed Oyster Shells for Fluoride Removal from Water

Elevated concentrations of fluoride ions (F−) in natural groundwater are a worldwide problem. Discarded oyster shells were ground to ≤100 µm particle size to produce oyster shell powder (OS). A subset of the OS was heated to produce calcined oyster shell (COS). A subset of the COS was further treated with 1 M phosphoric acid to produce phosphoric-acid-treated oyster shell (POS). OS and COS were combined with phosphoric acid (1.6 mM and 3.2 mM) to produce OS + P (oyster shell with phosphoric acid) and COS + P (calcined oyster shell with phosphoric acid). OS and COS removed 46% and 50% (10 g/L of sorbent dose) but POS, OS + P and COS + P removed 96%, 100% and 76% (1 g/L of sorbent dose) when the initial concentration of fluoride was 10 mg/L. The sorption kinetics of POS, OS + P and COS + P followed second-order reaction rates, and sorption isotherms of all sorbents were well-described by the Freundlich sorption isotherm. These results indicate that oyster shells can be an effective sorbent for fluoride removal, with the added benefit of re-use of a waste product.

Highly selective and label-free Love-mode surface acoustic wave biosensor for carcinoembryonic antigen detection using a self-assembled monolayer bioreceptor

A Love-mode surface acoustic wave (SAW) biosensor based on ST-cut quartz was developed for highly selective and label-free detection of carcinoembryonic antigen (CEA). The delay line area of an interdigital transducer (IDT) based SAW device was coated with gold and then chemically modified through thioglycolic acid–EDC/NHS reaction mechanism. A self-assembled monolayer of anti-CEA was further immobilized on the bioreceptors through the coupling layer. The biosensing capability of the SAW device was evaluated using solutions of CEA with various concentrations and limit of detection was obtained at 0.31 ng/ml of CEA, which is better than the results reported by the literatures available for CEA detection using SAW device. The real-time detection capability of the biosensor was evaluated using clinical serum samples and selectivity was evaluated using mixed solutions of CEA with other common tumor marking proteins. Long-term stability of the biosensor was also evaluated over a period of 30 days and the immunoassay response has shown only 8% decrease in performance within the whole period. The binding of CEA onto the bioreceptor was evaluated through Langmuir and Freundlich sorption isotherm kinetic studies as well.

Prediction of phosphorus sorption indices and isotherm parameters in agricultural soils using mid-infrared spectroscopy

Phosphorus is a macro nutrient essential for optimum crop growth and animal health. The soil’s ability to supply P in an available form is influenced by sorption capacity and P binding energies in soil. These properties are usually derived from sorption isotherms that are time consuming and difficult for routine analysis. Mid-infrared diffuse reflectance Fourier transform (MIR DRIFT) spectroscopy is a rapid analysis technique that can potentially replace extractive and digestive techniques traditionally used in soil analysis. This study explored the application of MIR DRIFT in combination with chemometrics, to predict indicators of soil fertility and quality, specifically, P sorption properties. Using an archive of 11 great soil groups a P sorption reference library was generated using five different sorption models; (1) single point sorption index; (2) Langmuir sorption isotherm in the 0–25 mg l−1 P range; (3) Langmuir sorption isotherm in the 0–50 mg l−1 P range; (4) Freundlich sorption isotherm in the 0–25 mg l−1 P range; and (5) Freundlich sorption isotherm in the 0–50 mg l−1 P range. Thirteen reference values were generated for each sample for calibration and validation of P sorption models developed from MIR DRIFT spectra. Validation of the single point P sorption index and Langmuir parameters were satisfactory for rough screening with the exception of the Langmuir binding energy in the 0–50 mg l−1 P range (k50 [8]). The P sorption capacity remaining was the best predicted parameter and the Freundlich sorption isotherm predictions were poor. The results indicated that there is potential for benchtop MIR to describe P sorption properties in agricultural soil to improve management decisions and that soil specific models could be developed to further enhance prediction performance.

Removal of Acidic Dyes from Aqueous Media Using Citrullus Lanatus Peels: An Agrowaste-Based Adsorbent for Environmental Safety

In this work, removal of fluorescein and eosin dyes using common agrowaste, i.e., peels of water melon (Citrullus lanatus) (WMP), has been studied in the batch mode. The sorbent material (WMP) was characterized by using scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis. The sorbent was chemically modified by subjecting it to 0.1 N HNO3 and 0.1 N NaOH solutions. Different parameters such as sorbent dose, pH, temperature, and agitation speed were optimized to investigate the sorbent efficiency for fluorescein and eosin dyes. Among three forms (raw, base-treated, and acid-treated), the base-treated form exhibited higher removal efficiency, followed by acid-treated and then the raw form. Generally, range for the removal of fluorescein and eosin was found to be 48.06–88.08% and 48.47–79.31%, respectively. Mathematical modeling of sorption data by Langmuir and Freundlich sorption isotherms and thermodynamic investigations were carried out to check the suitability of these agrowaste materials on bulk scale. The promising results concluded that peel of water melon (common agrowaste) can be potentially utilized for the removal of toxins.

Pomegranate peel and orange juice by-product as new biosorbents of phenolic compounds from olive mill wastewaters

Several wastes and residues have been studied for the adsorption of phenolic compounds with varying success. However, new economical, easily available, and highly effective adsorbents are still needed. The purpose of this work is to consider the potential of two food wastes derived from agricultural activities, the non-modified pomegranate peel and orange juice by-product, after the removal of their own phenolic content, for phenolics sorption from olive mill wastewater. This procedure is the second step of an integrated approach for complete utilization of these wastes in recovering valuable ingredients, while succeeding total depollution. Initially, the equilibrium time was investigated and afterwards, the effects of sorbent mass concentration (0.01–0.02 g/mL), temperature (20–60 °C), solution’s pH (4–7), initial sorbate concentration (50–500 mg/L), and sorbent particle size on total phenols uptake were studied. The highest adsorption efficiencies obtained were 93.13 and 89.59% using pomegranate peel and orange juice by-product, respectively. Total phenols removal efficiency was maximum at pH 4.75 and was improved by decreasing adsorbents dosage, initial sorbate concentration, temperature, and sorbents particle size. The sorption followed the intra-particle diffusion model and was described better by the Freundlich sorption isotherm. The results indicated that the studied materials could be employed as alternative low-cost biosorbents.

KOH modified Thevetia peruviana shell activated carbon for sorption of dimethoate from aqueous solution

Modified Thevetia peruviana shell activated carbon for sorption of dimethoate from aqueous solution derived with potassium hydroxide (KOH) was studied at different concentrations for its potential application in water treatment. The batch sorption was investigated using dimethoate solution of 10–100 mg/L concentrations. Proximate analysis was determined and changes on the surfaces and structure of the TPS were characterized after chemical activation with KOH using XRD, FTIR, SEM–EDAX, pHpzc, BET. The quantum chemical calculation for dimethoate yielded molecule associated energies of –9.8421 (HOMO) and –2.3879 (LUMO) and a total energy of –53,376.2. The kinetic of the sorption was modeled which indicated the sorption equilibrium time as 90 min and pseudo-first order kinetics model showing R2 = 0.994 provided a better description of the process. Analysis of sorption equilibrium revealed that the data fitted well to Freundlich sorption isotherm model (R2 = 0.966), indicating multi-layer sorption of dimethoate on the surface of sorbent. The sorption of dimethoate onto KOHTPS shows 92.60% removal efficiency.

Spectroscopic, thermal and equilibrium characterization of U(VI) ions sorption on inulin in the presence of phosphates

Sorption of U(VI) ions on inulin as the sorbent was investigated at the U(VI) concentrations ranging 0.0001–0.001 mol/dm3 in the absence and presence of phosphate ions P(V). Multilayer sorption of U(VI) was established based on a the Langmuir–Freundlich sorption isotherm. It was concluded, on the basis of the continuous variation method, that the (UO2)3(OH)5H2PO4 and (UO2)3(PO4)2 complexes were present in the sorbent phase during the simultaneous sorption of U(VI) and P(V) ions. XPS, FT-IR and thermal decomposition spectra of products of U(VI) sorption on inulin showed that U(VI) ions interacted with inulin via the CO and OH groups of the sorbent. With its maximum U(VI) sorption capacity of 78/mg/g and its easy thermal decomposition, i.e. easy utilization, inulin holds a good position among known sorbents.

Multifunctional Group Biomass in Biosorption of Cu2+ from Aqueous Solution: Kinetics and Isotherm Studies

A novel, fibrous and multifunctional group surface biosorbent was prepared from the waste of Irvingia gabonensis (Dika nut-DN) seed. The biosorbent potential in cheap environmental remediation was tested using aqueous copper solution as adsorbate. Percentage Cu2+ removal was as high as 70 %. Sorption data were tested with various isotherms and kinetics models. Monolayer sorption dominates the uptake of Cu2+ onto DN with maximum monolayer sorption capacity of 227.27 mg/g. Some level of multilayer sorption also occurred within the Cu2+ -DN system thus a greater than 0.9 correlation coefficient recorded for the Freundlich sorption isotherm. Possible Cu2+ uptake mechanism onto DN was proposed. Pseudo second order kinetics best described the biosorption data while desorption results showed that Cu2+ was stable on DN surface. Keywords: Biomass, Irvingia gabonensis, Kinetics, Isotherms, Thermodynamics. ---------------------------------------------------------------------------------------------------------------

Adsorption of sulfamethoxazole and sulfapyridine antibiotics in high organic content soils

Many antibiotics, including sulfonamides, are being frequently detected in soil and groundwater. Livestock waste is an important source of antibiotic pollution, and sulfonamides may be present along with organic-rich substances. This study aims to investigate the sorption reaction of two sulfonamides, sulfamethoxazole (SMZ) and sulfapyridine (SPY) in two organic-rich sorbents: a commercial peat soil (38.41% carbon content) and a composted manure (24.33% carbon content). Batch reactions were conducted to evaluate the impacts of pH (4.5–9.5) and background ions (0.001 M–0.1 M CaCl2) on their sorption. Both linear partitioning and Freundlich sorption isotherms fit the reaction well. The n values of Freundlich isotherm were close to 1 in most conditions suggesting that the hydrophobic partition is the major adsorption mechanism. In terms of SMZ, Kd declined with increases in the pH. SPY has a pyridine group that is responsible for adsorption at high pH values, and thus, no significant trend between Kd and pH was observed. At high pH ranges, SPY sorption deviated significantly from linear partitioning. The results suggested the sorption mechanism of these two sulfonamide antibiotics tended to be hydrophobic partitioning under most of the experimental conditions, especially at pH values lower than their corresponding pKa2. The fluorescence excitation emission matrix and dissolved organic carbon leaching test suggested composted manure has higher fulvic acid organics and that peat soil has higher humus-like organics. Small organic molecules showed stronger affinity toward sulfonamide antibiotics and cause the composted manure to exhibit higher sorption capacity. Overall, this study suggests that the chemical structure and properties of sulfonamides antibiotics and the type of organic matter in soils will greatly influence the fate and transport of these contaminants into the environment.