Environmental Application of Acid Activated Kaolinite-Glauconite Clay Assisted By Microwave Irradiation

Crude kaolinite-glauconite clay was active with hydrochloric acid for various times under variable microwave irradiation power. The influence of activation parameters (power and/or time) on the structural and textural properties of the treated samples has been studied. The modifications were evaluated by XRD, FTIR, XRF, SEM, BET, grain size and zettametry. The XRD and IR results show that acid activation reveals only weak changes on crystallinity of samples. However, HCl activation of clay assisted by microwave modifies morphology and size of grains with a little variation of the specific surface area values. The adsorbing power of the raw and activated clay was tested with methyl orange dye and the adsorption isotherms were modeled using Langmuir and Freundlich models. This study showed that the maximum adsorbed quantity of dye passes from 3.21mg/g for the untreated raw clay to 4.29mg/g for the activated clay irradiated 2 min under microwave at a power of 900W and that the Langmuir model is the most adequate to describe the adsorption process.

Preparation of Functionalized Hydroxyapatite with Biopolymers as Efficient Adsorbents of Methylene Blue

In this study, we reported the synthesis of hydroxyapatite modified with biopolymers as λ-carrageenan and sodium alginate, which could be used as effective adsorbents of cationic dyes. Evidence of chemical modification was proved through chemical analysis, Fourier Trans-form Infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and specific surface area. The adsorption process was studied using methylene blue as representative cationic dye. The adsorbed quantity reached, at equilibrium, 142.85 mg/g and 98.23 mg/g using hydroxyapatite-sodium alginate and hydroxyapatite-(λ-carrageenan), respectively. However, it does not exceed 58.8 mg/g in the case of the unmodified hydroxyapatite. The adsorption of methylene blue using hybrid materials complied well with the pseudo-second-order suggesting a chemi-sorption. Freundlich and Langmuir isotherm described well the adsorption mechanism of the hydroxyapatite-(λ-carrageenan) and hydroxyapatite-sodium alginate, respectively. The high capacities of MB removal obtained in this study suggest the potential use of these materials in the treatment from wastewaters.

Application of Innovative Analytical Modeling for the Physicochemical Analysis of Adsorption Isotherms of Silver Nitrate on Helicenes: Phenomenological Study of the Complexation Process

The interaction between the silver ion and the cyclic aromatic molecules, namely, the helicenes, is the subject of this paper. In fact, a silver complexation system based on quartz crystal microbalance (QCM) sensor with a functional film of helicenes has been designed and developed at four temperatures. The developed system, in which the sensor response reflects the adsorption of the hexahelicene and the heptahelicene, was able to control the complexed mass of silver for each concentration. Experimental outcomes indicated that the quartz crystal coated with heptahelicene is the adequate material for silver adsorption. Then, a theoretical study has been performed through two statistical physics models (SMPG and SMRG) in order to analyze the experimental adsorption isotherms of the two helicenes at the ionic scale. The SMRG model was developed using the real gas law and was satisfactorily applied for the microscopic investigation of the hexahelicene isotherms indicating that the lateral interactions between the adsorbates are responsible of the decrease of the adsorbed quantity at saturation. The interpretation of the two models’ parameters indicated that the adsorption of the two helicenes is an endothermic phenomenon. Interestingly, the heptahelicene is recommended for silver complexation because it shows the highest adsorption energies involving chemical bonds during the complexation process. The SMPG model and the SMRG model also allow prediction of three thermodynamic functions (configurational entropy, Gibbs free enthalpy, and internal energy) which govern the adsorption mechanism of silver on the two helicenes.

New Approach for Sulfadiazine Toxicity Management using Carboxymethyl Cellulose Grafted Acrylamide Hydrogel

Sulfadiazine (SZ), a small molecule sulfonamide that also named a 2-sulfanilamido-pyrimidine. SZ is an artificial bacteriostatic antibiotic through a widespread spectrum counter to numerous gram-negative and gram-positive bacteria. Sulfonamide antibiotics frequently identified in the earthly and water environment, but little acknowledgment about abiotic deprivation of these antibiotics. The SZ adsorption from aqueous solution studied in the present experiment utilizing carboxymethyl cellulose (CMC) grafted acrylamide (AM) hydrogel as an adsorbent. Effect of time-related to equilibrium, salts, temperature, and pH value was accomplished using kinetics and thermodynamic studies. Fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) analysis accomplished for CMC-g-AM hydrogel before and after SZ adsorption. The study showed higher adsorption of the SZ on these hydrogels, and the degrees of SZ adsorption on the hydrogels decreased with increasing temperature (exothermic process). Adsorbed quantity of SZ on the surface was declined as the pH augmented. KCl’s influence on adsorption is more than that of NaCl, and the CaCO3 is more than of KCl. Spontaneous and feasible adsorption takes place, and adsorption of SZ on hydrogel fits well with the Freundlich model.

EFFECT OF IONIC STRENGTH FROM DIFFERENT SALT RESOURCES ON BORON ADSORPTION IN CALCAREOUS SOIL

This study was conducted in the laboratories of Soil and water resources Department, College of Agricultural Sciences Engineering, University of Baghdad for the purpose of disclosing the effect of ionic strength from different salt mixtures on the adsorption of Boron in a silty clay loam calcareous soil taken from the prior location of the college of Agriculture in Abu Ghraib, after a quite equilibrium of Boron solution prepared from Boric acid at( 0, 1, 5, 7.5, 10 and 20) μmole B.ml-1 at 298 Kalvin. Three solutions with different ionic strength were used( 0.1, 0.2, 0.3) mole.L-1 of four different salts CaCl2, MgCl2, NaCl and composed salt of the three salts at 3:1:1 ratios respectively. Langmuir single surface line equation was used for better description of the reactions of Boron adsorption in soil.Results showed a significant increase in Boron adsorbed quantity in soil with the increase of the applied Boron. The increase in ionic strength led to a significant increase in adsorbed Boron for all salts with different rates. These different salts showed significant differences in adsorbed quantity of Boron, where CaCl2 treatment was exceeded followed by MgCl2, mixture salt, then NaCl treatments as an averages of the three ionic strengths where it reached (68.95, 65.26, 58.38 and 44.37) μmole B.gm-1 soil respectively and at maximum adsorption capacity (Xm) at (58.26, 55.92, 47.90, 46.17) mg B. Kg-1 soil, while bonding energy to soil particles (K) was (0.279, 0.244, 0.244 and 0.125) ml μ B for the mentioned salts respectively. In general, soil is considered to have a high maximum adsorption capacity (42.88 mg B.Kg-1 soil) and low bonding energy (0.216 ml μ-1 B) .

Effective Adsorption of Methylene Blue dye onto Magnetic Nanocomposites. Modeling and Reuse Studies

In the present study, new adsorbent beads of alginate (A)/maghemite nanoparticles (γ-Fe2O3)/functionalized multiwalled carbon nanotubes (f-CNT) were prepared and characterized by several techniques, e.g., N2 adsorption-desorption isotherms, Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA/DTG), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM) and further tested for the adsorption of the dye methylene blue (MB) from water. The beads (A/γ-Fe2O3/f-CNT) presented a relatively low BET specific surface area value of 59 m2g−1. The magnetization saturation values of A/γ-Fe2O3/f-CNT beads determined at 295 K was equal to 27.16 emu g−1, indicating a magnetic character. The time needed to attain the equilibrium of MB adsorption onto the beads was estimated within 48 h. Thus, several kinetic and isotherm equation models were used to fit the kinetic and equilibrium experimental results. The number of adsorbed MB molecules per active site, the anchorage number, the receptor sites density, the adsorbed quantity at saturation, the concentration at half saturation and the molar adsorption energy were quantified using the monolayer model. The calculated negative ΔG0 and positive ΔH0 values suggested the spontaneous and endothermic nature of the adsorption process. In addition, A/γ-Fe2O3/f-CNT composites can be used at least for six times maintaining their significant adsorptive performance and could be easily separated by using a magnet from water after treatment.

Use of sweet ‘Pêra’ peel as an adsorbent in the treatment of textile effluents

ABSTRACT The disposal of industrial wastewater into aquatic bodies without proper treatment can cause severe damage to the environment and human health. The objective of this study was to perform the drying of the sweet orange (Citrus sinensis L. Osbeck) peel cultivar Pêra and evaluate the viability of its use as biosorbent in the removal of a direct dye. Drying was carried out in an oven with air circulation at temperatures of 60 and 80 ºC. The mathematical models of Page, Henderson and Pabis, Logarithmic, Midilli and Two-term exponential were fitted to the moisture data as a function of time. The material was characterized by scanning electron microscopy, point of zero charge, and infrared spectroscopy. In the adsorption study, a complete 24 factorial design was used to analyze the influence of mass, initial concentration, solution pH and contact time on adsorbed quantity (qt) and removal percentage of the dye (R%). In the drying, the two-term exponential model fitted best to the experimental data. The characterization of the material indicated that the adsorbent has zero charge point of 3.5 and porous structure, and the infrared analysis indicated the presence of carboxylic and hydroxyl groups. In the adsorption, the adsorbed quantity of the dye increased under conditions of lower pH and biosorbent mass and higher initial concentration and contact time. The removal percentage of dye increases with higher biosorbent mass. The biosorbent used is a promising waste for the adsorption of the burgundy-16 dye.

Adsorption thermodynamics and isosteric heat of adsorption of Thymol onto sodic, pillared and organic bentonite

We studied the temperature effects on thymol adsorption on sodium and modified clays from Nador, Morocco. The clay samples used for these analyses were purified and modified by sodium, Al13 and Cetyl Pyridinium chloride before they were used as an adsorbent for the adsorption of thymol from aqueous solution in batch adsorption procedure. The adsorption experiments were carried out as a function of temperature. The adsorption was found to be strongly dependent on the temperature. The Freundlich isotherm model showed an excellent fit to the equilibrium adsorption data. This equation indicates that the logarithm of KF is a linear function of temperature, and it decreases with temperature. The mean free energy (E) estimated from the Rankine (Calendar) modified model indicated that there is a significant relationship between adsorbed quantity and temperature and the primary mechanism governing the sorption process was a physisorption mechanism. The Arrhenius and Eyring equations were used to obtain the activation parameters such as activation energy (Ea), and enthalpy (ΔH°), entropy (ΔS°) and free energy (ΔG°) of activation for the adsorption system. Thermodynamic studies suggested the spontaneous and endothermic nature of adsorption of thymol green by sodium and purified bentonite. The isosteric heat of adsorption (ΔHX) was also determined from the equilibrium information using the Clausius–Clapeyron equation. ΔHX increased with increase in surface loading, indicating some lateral interactions between the adsorbed molecules.

Optimization of cadmium(II) adsorption onto modified and unmodified lignocellulosics (rice husk and egussi peeling)

<p>The present study is based on the adsorption of cadmium (II) ions on rice husk and egussi peeling, unmodified and modified with nitric acid in aqueous solution, using batch technique. It was carried out as a function of contact time, dosage, pH and initial concentration. The equilibrium time was achieved within 25 minutes for unmodified rice husk (Glu NT) and 20 minutes for unmodified egussi peeling (Cuc NT) with an adsorbed quantity of 13.18 mg/g. In the case of modified materials, we obtained 15 minutes for modified rice husk (Glu HNO3) and 10 minutes for modified egussi peeling (Cuc HNO3) with an adsorbed quantity of 18.77 mg/g. The maximum biosorption occurred at pH 5.5 for all biosorbents. The adsorbent mass for maximum adsorption was 0.4 g giving an adsorption capacity of 62.02 % for unmodified adsorbents. In the case of modified adsorbents, the minimal mass at which maximum adsorption occurred was 0.4 g giving an adsorption capacity of 98.33 % and 0.6 g giving an adsorption capacity of 98.33 % for modified rice husk and egussi peeling respectively. The adsorbent/adsorbate equilibrium was well described by the pseudo-second order kinetic model and by Langmuir’s and Freundlich adsorption model. This models showed that the adsorption of cadmium (II) is a chemisorption process.</p>