Comparison of the sorption properties of natural and synthetic zeolites for the purification of aqueous solutions from cobalt: sorption of the cobalt from aqueous solutions in dynamic conditions and the quantitative determination of cobalt by the PIXE method

A methodology of quantitative determination of cobalt using the PIXE method has been developed. The method is based on the use of instant nuclear-physical analysis with the inducement of a target by a 1.6 MeV proton beam and the recording of the characteristic X-ray emission of the K-series of the cobalt. The linear relationship between the quantitative content of cobalt strontium and its X-ray emission K-shell was obtained. The sorption of cobalt by natural and synthetic zeolites from aqueous solutions in dynamic conditions has been studied. Sorption of cobalt with clinoptilolite after 80 cycles of sorption was about 60%. Sorption of cobalt after 80 cycles of sorption by zeolites NaX and NaA was 86 and 70%. Consideration was given to the influence of competing ions (sodium) on the sorption of cobalt by zeolites. The introduction of competing ions leads to a decrease in sorption of the cobalt by 25–60%, depending on the content of competing ions.     

Novel crosslinked gels with starch derivatives. Polymer‐water interactions. Applications in waste water treatment.

Crosslinked polymers containing starch have been used for the recovery of various pollutants from aqueous solutions. These polymers have been prepared by reticulation of starch‐enriched flour using epichlorohydrin as crosslinking agent. Several studies (kinetics, time, concentration, role of crosslinking agent) are presented here. The results show that these polymers exhibit high sorption capacities toward substituted phenol derivatives. The mechanism of sorption is both physical and steric adsorption in the polymer network and/or the formation of hydrogen bond and hydrophobic interactions.     

Sorption characteristics of uranium onto composite ion exchangers

The composite ion exchangers were tested for their ability to remove UO₂ ²⁺ from aqueous solutions. Polyacrylonitrile (PAN) composites having natural zeolite, clinoptilolite, and synthetic zeolite, zeolite X, were used as an adsorbents. The influences of pH, U(VI) concentration, temperature and contact time on the sorption behavior of U(VI) were investigated in order to gain a macroscopic understanding of the sorption mechanism. The optimum adsorption conditions were determined for two composites. The sorption behaviors of uranium on both composites from aqueous systems have been studied by batch technique. Parameters on desorption were also investigated to recover the adsorbed uranium.     

Sorption of iron(III) in ionic and colloidal states on iron(III) oxide deposited on a silica gel sufrace

The sorption of iron(III) in ionic and colloidal states on iron(III) oxide deposited on a silica gel surface has been studied as a function of pH of aqueous solution by batch equilibrations. The behaviour of Fe³⁺ and colloidal Fe(III) on the sorbent column has also been investigated. Conditions for sorption of iron from aqueous solutions are given. The colloidal iron(III) can be quantitatively separated from Fe³⁺ on the sorbent column under given experimental conditions.     

Isosteric heats of sorption of 1-naphthol and phenol from aqueous solutions by beta-cyclodextrin polymers

The sorption of phenol and 1-naphthol from aqueous solutions by beta-cyclodextrin polymers has been analyzed using the isosteric heat approach. This has proven to be a useful tool for comparing the interactions between the sorbents and the sorbates. With the purpose of ascertaining the role of the cyclodextrin cavities and the crosslinking network in the sorption process, analogous sucrose polymers have been prepared using the same crosslinking reagents (epichlorohydrin, succinyl chloride, 1,6-hexamethylene diisocyanate, and toluene-2,4-diisocyanate). The two studied sorbates, phenol and 1-naphthol, also show important differences in their affinities for the cyclodextrin cavities and the crosslinking networks.     

Sorption of Water-Soluble Copper(II) Compounds on Clinoptilolite

Copper(II) sorption on clinoptilolite from aqueous solutions with different pH was studied. The results were analyzed using the calculated distribution of water-soluble copper(II) species at different pH. The best conditions of copper(II) sorption on clinoptilolite from aqueous solutions were determined.     

Sorption of Copper(II) Ions with Nanosized Magnesium Phosphate

A new approach to the preparation of a nanosized sorbent based on magnesium phosphate has been developed. The patterns of copper(II) ions sorption with nanosized magnesium phosphate from aqueous solutions have been investigated. The sorption parameters have been determined, and the kinetics and mechanism of the processes have been elucidated. The high sorption ability of the nanoscale sorbent has been shown in comparison with existing sorbents based on magnesium phosphate.     

Sorption behaviour of bifenthrin on cork

Biphentrin, a known pyrethroid, was studied, aiming its removal from aqueous solutions by granulated cork sorption. Batch experiments, either for equilibrium or for kinetics, with two granulated cork sizes were performed and results were compared with those obtained with of activated carbon sorption. Langmuir and Freundlich adsorption isotherms were obtained both showing high linear correlations. Bifenthrin desorption was evaluated for cork and results varied with the granule size of sorbent. The results obtained in this work indicate that cork wastes may be used as a cheap natural sorbent for bifenthrin or similar compounds removal from wastewaters.     

Characterization of modified clinoptilolite

Samples of clinoptilolite were modified using insoluble hexacyanoferrate from aqueous solution. The modified samples were characterized by elemental analysis, powder X-ray diffraction, solid state NMR and vibrational spectroscopy. The sorption properties of modified clinoptilolite were studied, too. Higher affinity for¹³⁷Cs sorption in comparison with the natural clinoptilolite has been proved.     

The equilibrium characteristics of pyridoxine hydrochloride sorption on clinoptilolite

Pyridoxine hydrochloride (vitamin B₆) sorption by clinoptilolite from aqueous solutions has been studied at 283, 295, and 317 K. Enhancement of the sorption with decreasing temperature has been found. Isotherm of pyridoxine hydrochloride adsorption from dilute solutions may be described by the Langmuir theory. It has been shown that the monolayer coverage of clinoptilolite surface with pyridoxine occurs via the equivalent exchange with extra-framework cations of the sorbent. Thermodynamic parameters of vitamin monolayer adsorption have been determined. It has been concluded that the polymolecular adsorption is due to the formation of pyridoxine associates in the sorbent mesopores.     

Effect of pH, ionic strength, foreign ions and humic substances on Th(IV) sorption to GMZ bentonite studied by batch experiments

Bentonite has been studied extensively because of its strong sorption and complexation ability. Herein, GMZ bentonite from Gaomiaozi county (Inner Mongolia, China) was investigated as the candidate of backfill material for the removal of Th(IV) ions from aqueous solutions. The results indicate that the sorption of Th(IV) is strongly dependent on pH and ionic strength at pH < 5, and independent of ionic strength at pH > 5. Outer-sphere surface complexation or ion-exchange are the main mechanism of Th(IV) sorption on GMZ bentonite at low pH values, whereas the sorption of Th(IV) at pH > 5 is mainly dominated by inner-sphere surface complexation or surface precipitation. Soil fulvic acid (FA) and humic acid (HA) have a positive influence on the sorption of Th(IV) on bentonite at pH < 5. The different addition sequences of HA and Th(IV) to GMZ bentonite suspensions have no obvious effect on Th(IV) sorption to HA-bentonite hybrids. The high sorption capacity of Th(IV) on GMZ bentonite suggests that the GMZ bentonite can remove Th(IV) ions from large volumes of aqueous solutions in real work.     

Removal of radiocobalt form aqueous solutions by inorganic exchangers

The sorption of radiocobalt from aqueous as well as organic solvents by natural and treated clays has been investigated. The effect of many factors, such as time, pH, carrier concentration, etc., were studied. In was found that the uptake is maximum in neutral, or slightly alkaline solutions. The rate of sorption depends on the velocity of shaking, which may indicate the operation of the film-diffusion mechanism, in addition to some contribution from particle-diffusion mechanism, but the dependence of the rate on shaking velocity could be attributed to an increase in the surface area of the clays. The conclusion is that natural clays are well suited for the removal of radioactive cobalt with slight, if any modification. These clays may be considered superior to synthetic exchangers for the removal of⁶⁰Co, if the availibility and prices of the former are taken into account.     

Removal of tritium labeled compounds from waste solutions by Sephadex, mineral coal and alumina

Organic waste solutions containing tritium present two problems: the high toxicity of the solvents and the radioactivity of tritium. In this paper the sorption behavior of the radioactivity of tritium from aqueous and organic waste solutions, containing tritium labeled compounds, was studied in Sephadex, mineral coal and alumina. It was found that the tritium retention depends on the composition of the waste solutions. Mineral coal was the best of the three materials studied to retain the organic compounds labeled with this radionuclide.     

Sorption Behavior of Copper(II) on Freshly Precipitated Aluminum Hydroxide

The isotherms of copper(II) sorption from aqueous solutions on freshly precipitated aluminum hydroxide obtained by hydrolysis of pentahydroxomonochlorodialuminum were studied. The sorption efficiency of copper(II) was studied as influenced by pH. Sorption of copper(II) by two different mechanisms is discussed.     

酚醛型吸附树脂吸附咖啡因的热力学研究

利用酚醛型吸附树脂JDW－2（自制）和DuoliteS-761对咖啡因的吸附进行了研究，在303－323K和研究的浓度范围内，JDW－2和DuoliteS-761对咖啡因吸附平衡数据符合Freundlich吸附等温方程。Freundlich吸附等温线和等量吸附焓表明：JDW－2和DuoliteS-761对咖啡因吸附是放热过程，我们对咖啡因在JDW－2和DuoliteS-761上的吸附焓，自由能，吸附熵也作了测试，并对吸附行为作了合理解释。     

Sodium di-n-propyldithiophosphinate and activated carbon used for the concentrating of bismuth and its determination by atomic emission spectroscopy with inductively-coupled plasma

Sodium di-n-propyldithiophosphinate has been proposed as a reagent to improve the sorption properties of activated carbon. The conditions for sorption concentration and separation of bismuth from aqueous solutions were studied. Possibilities for desorption and subsequent determination of bismuth by atomic emission spectroscopy with inductively-coupled plasma were shown.     

Sorption of Nickel Ions from Aqueous Solutions by Ion Exchangers

Sorption of Ni²⁺ions from aqueous solutions by ion exchangers differed in their chemical nature and structure was studied. Based on the endothermic curves of ice melting obtained by a differential scanning calorimetry, the amounts of freezing and non-freezing water present in free volumes (pores) of the studied ion exchangers were calculated. Comparison of results obtained from the kinetic curves of nickel ion sorption with data on differential scanning calorimetry indicates a role of structural factor in the sorption of nickel ions. It was found that, depending on the total amount of freezing and non-freezing water, the KU-2-8 sulfonated cationite is the most preferable ion exchanger for the sorption of nickel ions from aqueous solutions. Therefore, sorbent efficiency in this case is determined by its structure rather than by chemical nature.     

Complexation and sorption studies of Co(II) with γ-alumina-bound fulvic acid: effect of pH,ionic strength,fulvic acid and alumina concentration

The removal of heavy metal ion Co(II) from aqueous solution is studied using γ-Al₂O₃ by batch technique. The experiments are performed at T = 20 ± 2 °C, in 0.01 M NaNO₃ solutions and under aerobic conditions. The effect of pH, ionic strength, fulvic acid (FA) and alumina concentration on the sorption of Co(II) on alumina are also respectively investigated. The pH affects the sorption of Co(II) significantly as compared with the effect of FA and ionic strength. The results indicate that strong chemical bonds are formed between Co(II) and the bare or FA coated alumina surface, and a transition from the adsorption to surface-induced precipitation of Co(II) on alumina surface takes place. The addition sequences of Co/FA on Co(II) sorption is also studied and the results indicate that the sorption of Co(II) in ternary system is independent of addition sequences. The results also suggest that the sorption of metal ions on mineral surface depends on the nature of mineral, nature of organic ligand and nature of metal ion.     

Sorption characteristics of an economical sorbent material used for removal radioisotopes of cesium and europium

Application study for the evaluation of sorption characteristics of sawdust as an economical sorbent material used for decontamination of radioisotopes cesium and europium from aqueous solution has been carried out in the present work. In this respect, sawdust (untreated and treated by HNO₃) has been prepared from the commercial processing of wood for furniture production. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N₂ adsorption and DFT software. Radiotracer method onto sawdust from aqueous solutions was studied in a batch technique with respect to pH, contact time, temperature. The kinetics of adsorption of Eu³⁺ and Cs⁺ have been discussed using five kinetic models namely, pseudo-first-order model, pseudo-second-order model, Elovich equation, intraparticle diffusion model, and modified Freundlich equation that have been tested in order to analysis the experimental data. Kinetic parameters and correlation coefficients were determined. It was shown that the second-order kinetic equation could describe the sorption kinetics for two metal ions. The metal uptake process was found to be controlled by intraparticle diffusion. Thermodynamic parameters, such as ΔH, ΔG and ΔS, have been calculated by using the thermodynamic equilibrium coefficient obtained at different temperatures. The obtained results indicated that endothermic nature of sorption process for both ^152+154Eu and ¹³⁴Cs onto sawdust.     

Strontium(II) sorption by complexing o-hydroxy-azo-o’-hydroxy functionalized polystyrene polymer sorbents

Optimal parameters for strontium(II) complexing and sorption from aqueous solutions by sorbents based on styrene/divinylbenzene copolymers functionalized with a complexing o-hydroxy-azo-o-hydroxy functionality have been studied, namely, pH_opt, 50% sorption pH (pH₅₀), and the time and temperature of quantitative strontium(II) sorption. Strontium(II) sorption capacities have been determined for the sorbents under study; sorption isotherms have been constructed. For a complex formed with polystyrene-o-hydroxy-azo-o’-hydroxy-sulfobenzene, which is an efficient sorbent, the structure has been determined.