Fourier transform infrared–photoacoustic spectroscopy of poly (N-butyl methacrylate) adsorbed from solution on alumina

Fourier transform infrared–photoacoustic spectroscopy (FTIR–PA) has been used to investigate the adsorption of poly(n-butyl methacrylate) (PnBMA) from solution on alumina. Qualitative and quantitative analysis of the FTIR–PA spectra of PnBMA adsorbed from cyclohexane, benzene, and carbon tetrachloride on alumina were performed. The efficiency of adsorption was found to increase in the order of C₆H₁₂ > CCl₄ > C₆H₆. Methanol and tetrahydrofuran, on the other hand, showed negative adsorption. The effects of temperature and the amount of adsorbent were also investigated and it was observed that the adsorption of PnBMA has a negative temperature coefficient. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 1669–1674, 1998     

Adsorption of weak and non-electrolytes by activated carbon

Four activated carbons, one of them commercially available Darco active carbon and the remaining three from a series of coconut charcoals steam activated to varying degrees, are used to study the adsorption of weak and non-electrolytes. Introduction of —CI into the CH₃COOH molecule increases adsorption onto activated carbon while —OH and —NH₂ have the opposite effect. Substitution in the benzene ring shows that adsorption from aqueous solutions is in the order —NH₂, >—OH, >CO₂, >(—OH + —COOH). Effect of polarity of solvent on adsorption capacities is studied in H₂O, CHCl₃ and C₆H₆. Substitution of —Cl into the CH₃COOH molecule invariably increases the adsorption irrespective of the polarity of the solvent. On introducing a specific group in the benzene ring the adsorption is in the order: aniline ? phenol > benzoic acid > salicylic acid in H₂O medium but in CHCl₃ and C₆H₆ media aniline ? phenol > salicylic acid > benzoic acid. However, on comparing the results of individual adsorbates in three media, generally the magnitude of adsorption is H₂O > C₆H₆ ? CHCl₃. Adsorption of lower aliphatic acids (formic to caproic) from aqueous solutions increases regularly as one ascends the homologous series—a behaviour known as Traube's rule; however, of all the surface area available for N₂ adsorption, only a fraction of it is available for adsorption of the aliphatic acids.     

Use of sewage sludge for manufacturing adsorbents

This paper demonstrates that digested sludge can be reclaimed as an adsorbent for the removal of organic vapors (MEK, TOL and TCE) through the use of a pyrolysis. The manufactured adsorbent products were characterized by Brunauer, Emmentt and Teller (BET) surface area, carbon tetrachloride activity (ANSI/ASIM D3467–76'), and an elemental analysis test. Both the determination of CCl₄ activity and BET surface area were regarded as the useful means for estimation of the adsorption capacity of organic vapors on the reclaimed adsorbents. From the view point of specific surface area (CCl₄ activity number or adsorption capacity), it was concluded that the optimum condition for manufacturing the reclaimed adsorbent was by adding 5 kmols/m³ ZnCl₂ to the treated sludge and then heating the mixture at 550°C for 1 hour.     

Lanthanides Extraction by 8-Quinolinol and by a Mixture of Quinolinol and Trioctylphosphine Oxide

ABSTRACT

The solvent extraction of Nd³⁺ , Sm³⁺, Eu³⁺ , Gd³⁺, Dy³⁺ , Ho³⁺ , and Er³⁺ from a M ionic strength medium (CH₃COONa), pH (CH₃COOH) by 8-quinolinol (HOx) and by a mixture of HOx and trioctylphosphine oxide (TOPO) in CCl₄, CHCl₃, C₆H₆, C₆H₅—NO₂, C₆H₅—CH₃ C₆H₅Cl and C₆H₅—Br is studied using titrimetric methods. A synergistic factor of over 10,000 is obtained. The atomic number and diluent effects are evident in the calculated formation constants and the lanthanide separation factors. A combination of the data obtained and that of Th⁴⁺ indicates that an excellent separation of thorium from the lanthanides can be obtained with this extraction system.     

Preparation of poly(methyl methacrylate) by ATRP using initiators for continuous activator regeneration (ICAR) in ionic liquid/microemulsions

In this study, we reported the synthesis of poly(methyl methacrylate) (PMMA) polymers via initiators for continuous activator regeneration atom transfer radical polymerization using CCl₄ as initiator, FeCl₃·6H₂O/hexamethylene tetramine as catalyst complex, and 2,2′-azobis(isobutyronitrile) (AIBN) as reducing agent. The polymerization was conducted at 60 °C in the ionic liquid based microemulsion with hexadecyl trimethyl ammonium bromide (CTAB) as surfactant. Kinetics experimental results showed that the polymerization proceeded in a controlled/‘living’ process. The effects of the molar ratio of [CCl₄]/[FeCl₃·6H₂O], the concentration of AIBN, temperature and the concentration of CTAB on the polymerization was investigated. The effect of CTAB concentration on the resulting PMMA particle size was also investigated. The obtained polymer was characterized by proton nuclear magnetic resonance and gel permeation chromatography. The living characteristics were demonstrated by chain extension experiment.     

Adsorption behavior and radiation effects of a silica-based (Calix(4)+Dodecanol)/SiO2-P adsorbent for selective separation of Cs(I) from high level liquid waste

A macroporous silica-based (Calix[4]+Dodecanol)/SiO₂-P absorbent for separation of Cs(I) from HNO₃ solution was prepared by impregnating the 1,3-[(2,4-Diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene and its molecule modifier 1-dodecanol into a macroporous silica/polymer composite support. To establish its application into partitioning of Cs(I) from High Level Liquid Waste (HLLW), the adsorption properties and radiation effects on the adsorbent were investigated. The adsorbent showed a relatively large distribution coefficient of Cs(I) and fast equilibrium time in simulated HLLW. Additionally, the adsorbent under the gamma-ray field was found to be able to selectively adsorb Cs(I) with similar behavior to the adsorption without irradiation up to at least 170 kGy.     

A low-cost and environment friendly chitosan/aluminum hydroxide bead adsorbent for fluoride removal from aqueous solutions

A novel low-cost adsorbent named chitosan/Al(OH)₃·(CS/Al(OH)₃) bead was successfully prepared by employing AlCl₃·6H₂O aqueous solution as the solvent for CS. The CS/Al(OH)₃ beads were used for fluoride removal from water. The beads were synthesized using the chitosan and aluminum chloride with the mass ratio of 2:1 as the precursor and in situ generation of aluminum hydroxide sorbents in sodium hydroxide solution. Then, the beads were washed with distilled water to neutral and freeze dried. The sorbents were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), Fourier transform infrared spectrometry (FTIR), and X-ray diffractometry (XRD), respectively. Batch adsorption experiments were conducted to evaluate the parameters that affected the defluoridation capacity. The influencing parameters including pH, co-existing ions in water and initial temperature of the adsorption process were studied. The influence of temperature confirmed that the adsorption was spontaneous and endothermic. The adsorption isotherm of fluoride followed Langmuir isotherm model and the sorption kinetics was more suitable for pseudo-second-order kinetic model. The defluoridation capacity of chitosan/Al(OH)₃ calculated using Langmuir model was 23.06 mg/g (293 K, pH 4). The experimental results showed that the CS/Al(OH)₃ bead adsorbent is promising for the fluoride adsorption.     

Sequential-refining of crude glycerol derived from waste used-oil methyl ester plant via a combined process of chemical and adsorption

A sequential stage physico-chemical refining of crude glycerol, derived from a waste used-oil utilizing biodiesel (methyl ester) production plant, was performed by acidification, polar solvent extraction and activated carbon adsorption at a laboratory scale and ambient temperature. The effect of varying the acid type (H₃PO₄, H₂SO₄ and CH₃COOH) and pH (1-6), the type of polar solvent (CH₃OH, C₂H₅OH and C₃H₇OH) and their ratio to glycerol (3:1-1:3 v/v), and adsorption with activated carbon at different ratios of activated carbon to glycerol (40-200 g/l) on the purity of crude glycerol was explored. The highest glycerol purity (95.74 wt.%) was obtained with the sequential acidification to pH 2.5 with H₃PO₄ and phase separation, followed by extraction with C₃H₇OH at a solvent:crude glycerol ratio of 2:1 (v/v). Finally, adsorption with commercial activated carbon at 200 g/l also achieved a 99.7% color reduction.     

Hydrodechlorination of CCl4 over Pt/γ-Al2O3 prepared from different Pt precursors

The platinum particle size on γ-Al₂O₃ prepared from different platinum precursors such as Pt(NH₃)₂(NO₂)₂, H₂PtCl₆, and K₂PtCl₆, and its effect on hydrodechlorination (HDC) of CCl₄ with the variation of calcination temperatures was investigated. It concomitantly affects the products distribution and catalytic stability in HDC of CCl₄. To verify the effects of platinum particle size with different platinum precursors on the product distribution, the catalysts have been characterized by HRTEM and CO chemisorption, FT-IR, and TP methods (TPR, TPD and TPSR). The catalysts with small platinum particles, which possess low coordination number and electron-deficient character, favor the complete dechlorination of CCl₄ and produce CH₄ more selectively. It could be due to the strong adsorption strength of CCl₄ or the decreased activation energy of surface intermediates on small platinum particles. FT-IR studies reveal that the maximum peak position of linear-bonded CO shifted to the higher frequency with the increase of platinum particle size in all catalysts prepared from three different platinum precursors. While the selectivity to CH₄ increased with the decrease in the platinum particle size, the total amount of carbonaceous species on the platinum particles was enhanced. The larger the platinum particle, the higher the selectivity to CHCl₃ was obtained in all tested catalysts under the non-deactivating condition.     

TEMPERATURE EFFECT ON THE SYNERGISTIC SOLVENT EXTRACT ION OF LANTHANOIDES

The synergistic solvent extraction of Pr, Gd and Yd with mixtures of HTTA and Aliquat 336 in CCl₄C₆H₆ and CHCl₃ at 288,298,308 and 318 K has been studied. The values of the equilibrium constants as well as the values of the thermodynamic parameters have been calculated.     

Adsorptive separation of ethylene/ethane mixtures with CuCl@HY adsorbent: equilibrium and reversibility

In this work, we investigate the potential of CuCl-functionalized HY zeolite (CuCl@HY) as an effective adsorbent for the ethylene/ethane separation. The CuCl@HY adsorbents were prepared with CuCl₂ as precursor by a solid-state dispersion method, followed by the activation with CO. The CuCl@HY adsorbents with different CuCl loadings were investigated for ethylene and ethane adsorptions, and evaluated the reversibility for multiple ethylene adsorption/desorption cycles. The experimental results reveal that the optimal adsorbent with copper loadings of 5 mmol/g HY zeolite displays high ethylene adsorption capacity, high C₂H₄/C₂H₆ adsorption selectivity and good reversibility. In addition, the adsorption equilibrium isotherms of ethylene and ethane on CuCl@HY at temperatures up to 333 K can be well correlated by the Sips models, and the corresponding isosteric heats of adsorption are calculated using the Clausius–Clapeyron equation. The value of isosteric heat of adsorption suggests that the interaction of CuCl@HY with ethylene molecules is between physisorption and chemisorption.     

Epoxide functionalized γ-Al2O3/Fe3O4/SiO2 nanocomposite and comparative adsorption behavior of a model reactive azo dye

In this investigation, magnetic γ-Al₂O₃ nanocomposite polymer particles with epoxide functionality were prepared following a multistep process. The prepared nanocomposite polymer particle was named as γ-Al₂O₃/Fe₃O₄/SiO₂/poly(glycidyl methacrylate (PGMA). The surface property was evaluated by carrying out the adsorption study of Remazol Navy RGB (RN), a model reactive azo dye, on both γ-Al₂O₃/Fe₃O₄/SiO₂ and γ-Al₂O₃/Fe₃O₄/SiO₂/PGMA nanocomposite particles, that is, before and after epoxide functionalization. A contact time, temperature, adsorbent dose, and dye concentration dependent change in adsorption behavior was observed on both nanocomposite particles. The adsorption amount reached equilibrium (q_e) value within 5 minutes at the respective point of zero charge (PZC). The adsorption density of RN per unit specific surface area on epoxide functional γ-Al₂O₃/Fe₃O₄/SiO₂/PGMA nanocomposite polymer particles (1.30 mg/m²) was higher relative to that on γ-Al₂O₃/Fe₃O₄/SiO₂ nanocomposite particles (0.87 mg/m²). The optimum adsorbent dose for obtaining the maximum adsorption density was 0.01 g. Comparatively, Langmuir isotherm model was better to describe the adsorption process and the adsorption process was favorable at low temperature (283 K). Batch kinetic adsorption experiment suggested that a pseudo-second-order rate kinetic model is more appropriate. Nanocomposite polymer particles were used as adsorbent up to third cycle with almost 99% adsorption efficiency.     

Determination of pore size distribution and adsorption of methane and CCl4 on activated carbon by molecular simulation

A combined method of grand canonical Monte Carlo (GCMC) simulation and statistics integral equation (SIE) for the determination of pore size distribution (PSD) is developed based on the experimental adsorption data of methane on activated carbon at ambient temperature, T=299 K. In the GCMC simulation, methane is modeled as a Lennord-Jones spherical molecule, and the activated carbon pore is described as slit-shaped with the PSD. The well-known Steele’s 10-4-3 potential is used to represent the interaction between the fluid molecule and the solid wall. Covering the range of pore sizes of the activated carbon, a series of adsorption isotherms of methane in several uniform pores were obtained from GCMC. In order to improve the agreement between the experimental data and simulation results, the PSD is calculated by means of an adaptable procedure of deconvolution of the SIE method. Based on the simulated results, we use the activated carbon with the PSD as the prototype of adsorbent to investigate adsorption. The adsorption isotherms of methane and CCl₄ at 299 K in the activated carbon with the PSD are obtained. The adsorption amount of CCl₄ reaches 20 mmol/g at ambient temperature and pressure. The results indicate that the combined method of GCMC and SIE proposed here is a powerful technique for calculating the PSD of activated carbons and predicting adsorption on activated carbons.     

Sorption studies of CO<Subscript>2</Subscript>, CH<Subscript>4</Subscript>, N<Subscript>2</Subscript>, CO,O<Subscript>2</Subscript> and Ar on nanoporous aluminum terephthalate [MIL-53(Al)]

Aluminum terephthalate, MIL-53(Al), metal–organic framework synthesized hydrothermally and purified by solvent extraction method was used as an adsorbent for gas adsorption studies. The synthesized MIL-53(Al) was characterized by powder X-Ray diffraction analysis, surface area measurement using N₂ adsorption–desorption at 77 K, FTIR spectroscopy and thermo gravimetric analysis. Adsorption isotherms of CO₂, CH₄, CO, N₂, O₂ and Ar were measured at 288 and 303 K. The absolute adsorption capacity was found in the order CO₂>CH₄>CO>N₂>Ar>O₂. Henry’s constants, heat of adsorption in the low pressure region and adsorption selectivities for the adsorbate gases were calculated from their adsorption isotherms. The high selectivity and low heat of adsorption for CO₂ suggests that MIL-53(Al) is a potential adsorbent material for the separation of CO₂ from gas mixtures. The high selectivity for CH₄ over O₂ and its low heat of adsorption suggests that MIL-53(Al) could also be a compatible adsorbent for the separation of methane from methane–oxygen gas mixtures.     

Batch Removal of Crystal Violet from Aqueous Solution by H2SO4 Modified Sugarcane Bagasse: Equilibrium,Kinetic, and Thermodynamic Profile

Batch adsorption studies were carried out using H₂SO₄ modified sugarcane bagasse (HMSB) for the removal of hazardous Crystal Violet (CV) dye from aqueous solutions. The effects of initial solution pH, adsorbent dose, and temperature on the adsorption process were investigated. The Langmuir isotherm model well described the equilibrium dye uptake while the pseudo-second-order kinetic model showed good agreement with the experimental kinetic data. Gibb's free energy change (ΔG⁰) was spontaneous for all interactions, and the adsorption process exhibited endothermic enthalpy values. Results suggest that HMSB is an effective adsorbent for the removal of CV from wastewater.     

Characteristics of phosphate adsorption on ferric hydroxide synthesized from a Fe<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript> aqueous solution discharged from a hydrometallurgical process

Ferric hydroxide adsorbent was prepared by a chemical treatment process with H₂O₂, NaOH, and aeration from a Fe₂(SO₄)₃ aqueous solution as a side product discharged from the hydrometallurgical process used to extract neodymium. The ferric hydroxide was used as an adsorbent to prevent eutrophication in water. At the time of synthesis, the most important process variable is the pH condition, which, in this experiment, was changed from pH 3 to 13. The cost of synthesizing ferric hydroxide was sharply reduced by using ferric sulfate, which is considered a side product of the aforementioned hydrometallurgical process, as a starting material, and an adsorbent with high adsorption ability was prepared by controlling the pH level. Microstructural characterization of the synthesized ferric hydroxide revealed particles with a specific surface area of 194.2 m²/g and an average pore diameter of 2.66 nm at pH 6 and 298 K. A column-type packed-bed adsorption experiment was conducted under the following conditions: a flow rate of 0.567 BV/min (3.2 mL/min), 298 K, and atmospheric pressure. The results of the adsorption performance test indicated that the adsorption efficiency of phosphate at concentrations of 10 ppm was 100% at a flow rate of 0.567 BV/min within a contact time of 2 min, and the maximum adsorption capacity for phosphate ions was 65 mg/g.     

Removal of methylene blue (aq) using untreated and acid‐treated eucalyptus leaves and GA‐ANN modelling

In the present batch study, eucalyptus leaves (EUL), H₂SO₄‐treated eucalyptus leaves (SEUL), and H₃PO₄‐treated eucalyptus leaves (PEUL) are used as bio‐adsorbents for the removal of methylene blue (MB). The bio‐adsorption is executed to inspect the results of the variation between different experimental variables such as pH (2–10), adsorbent dose (1–10 g/L), contact time (5–360 min), and temperature (298–318 K) on the bio‐adsorption of MB. The Langmuir isotherm (R² = 0.99) fitted adequately to the bio‐adsorption data for the initial MB concentrations of 10–300 mg/L. It is also necessary to mention that the MB bio‐adsorption occurred in the order of a monolayer on the EUL, SEUL, and PEUL. The bio‐adsorption kinetics have been fitted by the pseudo‐second‐order model (R² ≥ 0.99) for various MB concentrations. The maximum bio‐adsorption capacity was 194.34 mg/g and was achieved for the H₃PO₄‐treated eucalyptus leaves (PEUL). These results showed that EUL, SEUL, and PEUL may be utilized as a favourable low‐cost bio‐adsorbent to eliminate MB from aqueous solutions. With safe disposal methods in mind, this investigation has revealed the eco‐friendliness of the bio‐adsorbents. A prediction of the removal percentage of methylene blue using a genetic algorithm (GA) from the data collected from the experiment has also been tested. The results related to the prediction using the GA‐ANN are accurate.     

New applications for carbonaceous adsorbents

The most important adsorption properties of carbonaceous adsorbents are based on the microporous structure which can be determined by the mechanism of pore filling at equilibrium and by the diffusion behaviour of adsorbent molecules from the external surface into the grain. New processes of application of granular activated carbon in the gaseous phase besides the solvent recovery have been developed for the adsorption of sulfur containing and radioactive gases and in the aqueous phase for the purification of drinking and wastewater. New carbon molecular sieves are the base for gas separation processes, e.g. O₂- or N₂-recovery from air or H₂-recovery from H₂ containing gases.     

Influence of Magnetic Nanoparticles on Surface Changes in CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript>/Nerium Oleander Leaf Waste Activated Carbon Nanocomposite for Water Treatment

The paper reports on the successful use of the nano crystalline cobalt ferrite doped Nerium oleander leaf waste activated carbon (CoFe₂O₄/NOAC) synthesized by an urea assisted auto combustion technique to assess accurate kinetics and equilibrium parameters regarding the investigation of adsorption. The specific features of nano composite were investigated by various analytical techniques such as Scanning electron microscope with EDAX, powder X-ray diffraction study, BET surface area analysis, TG and DSC, Vibrating Sample Magnetometer. The BET analysis indicates that CoFe₂O₄ nano particles embedded in NOAC have increased the pore diameter for better adsorption. TG and DSC show the thermal stability of composite. The VSM study shows the Ferro magnetic behavior of nano composite which revealed that CoFe₂O₄/NOAC could be separated and retrieved easily by an external magnet after adsorption of AV49. The efficiency of adsorption of AV49 from aqueous solution was investigated through a series of batch experiments by using CoFe₂O₄/NOAC. The batch adsorption experiments showed the efficient removal on CoFe₂O₄/NOAC under optimum conditions such as pH 6.5, contact time-55 min and adsorbent dosage-50 mg. Adsorption kinetics—Pseudo first order and second order, Isotherms—Langmuir and Freundlich have been adapted to analyze the adsorption capacity. The results showed that the adsorption followed the pseudo second order kinetics and Langmuir isotherm equation is the best to describe the adsorption process. According to the thermodynamic study, it was very effective at higher temperatures also. The thermodynamic parameters ?G^o, ?H^o and ?S^o were also evaluated for this adsorption.     

Efficient Cycle Recovery of Hydrogen from a Low Concentration Pyrolysis Gas Stream by Pressure Swing Adsorption – An Experimental Evaluation

Breakthrough curves, cycle mass balances, and cycle bed productivities (mg H₂ per gram of adsorbent) on three dual adsorbent amounts (g) of 2,892, 1,963, and 1,013 respectively each filling 200 cm, 135 cm, and 70 cm of a 5.0 cm internal diameter stainless steel pipe were performed. The approximate optimum (sludge pyrolysis) synthesis gas with composition in volume % of 45% H₂/35% CO/20% CH₄ was used as the feed gas with molecular sieve 5 Å and activated carbon as adsorbents. Impurity breakthroughs occurred at ～14.9, 12.3, and 5.0 minutes respectively for % cycle recoveries of 72.2, 65.0, and 60.2 using 2,892, 1,962, and 1,013 g of adsorbent respectively. Our results indicated that basing % recycle recovery on cycle bed productivity can enable efficient hydrogen recovery with savings on adsorbent amount. An optimum cycle bed productivity of 2.3 mg H₂/g of adsorbent corresponded to a cycle recovery of 66.2% for 2,300 g of adsorbent used. Only 1.7 mg H₂/g of adsorbent was obtained for a cycle recovery of 72.2% requiring up to 2,800 g of adsorbent. This makes economic sense in the pressure swing adsorption separation of hydrogen from traditionally low hydrogen concentration biomass sources.