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(Pyridine-2,5-diylbis(azaneylylidene)) bis-(methaneylylidene)) bis(benzene-5,1,3-triyl) tetrakis (hydrogen phosphonate) (PZMB) was successfully synthesized for Th(IV) and Ce(IV) adsorption, the adsorption parameters evaluated and found to be pH 3.5, time 60 min, dose 0.15 g. Adsorption kinetics, isotherm, and thermodynamics studies. Adsorption kinetics studies show that adsorbent follow pseudo-second-order model while isotherm studies conclude that adsorption processes fitted Langmuir and D-R isotherm model. The maximum adsorption capacity of BZMB of Th(IV) and Ce(IV) are 366.4 and 244.53 mg/g respectively, Thermodynamic studies indicate both adsorption processes exhibited by the PZMB were endothermic, spontaneous and sorption occurs in a random manner. [ABSTRACT FROM AUTHOR]

A novel tentacle-type chitosan-based aerogel with swelling resistance was prepared via sol-gel technology using resorcinol as enhancer and g-C 3 N 4 as tentacle. The introduction of resorcinol and g-C 3 N 4 could not only increase the stability of the chitosan-based aerogel but also reduce the inter-molecular and intra-molecular interactions in chitosan, thereby enhancing the response of active sites to thorium. The adsorption performance of the chitosan-based aerogel for thorium from solution was verified by static and dynamic adsorption experiments. The results showed that the chitosan-based aerogel possessed an outstanding adsorption property for thorium with a short equilibrium time (20 min), a fast adsorption rate (103.9 mg/(g·min)), a high removal efficiency at low concentration (99.4 %) and a large static saturated adsorption capacity (526.2 mg/g). The dynamic adsorption experiments showed that the maximum dynamic adsorption capacity of the chitosan-based aerogel reached about 499.7 mg/g, which was consistent with static adsorption, far exceeding the reported chitosan-based adsorption materials. The results indicated that the capture of thorium on the tentacle-type chitosan-based aerogel was controlled by various factors, such as electrostatic interactions, surface complexation and cation-π effect. In a word, the tentacle-type chitosan-based aerogel could be used as a promising adsorbent for the remediation of thorium-containing wastewater. [Display omitted] • A tentacle-type chitosan-based aerogel with swelling resistance was prepared. • CN@CRFA was used for thorium removal with high adsorption affinity. • The adsorption capacity for thorium on CN@CRFA was 526.2 mg/g. • The thorium adsorption rate on CN@CRFA reached 103.9 mg/(g·min). [ABSTRACT FROM AUTHOR]

Immobilized Cystoseira indica algae and Saccharomyces Cerevisiae on the silica gel were used for the biosorption of Th­(IV) from aqueous solutions. Ability and capacity of bi-functionalized algae-­yeast biosorbent for adsorption of thorium­(IV) from aqueous solutions were investigated in a batch method. The response surface methodology (RSM) based on the central composite design (CCD) was used to investigate the effect of pH (2-6), time (10-180 min), initial thorium(IV) concentration (50-300 mg/l) and adsorbent dosage (0.5-5 g/l) on the sorption of thorium­(IV) from aqueous solutions, and to optimize the biosorption of Th­(IV). Variance analysis showed that the adsorbent dosage, initial Th(IV) concentration, time and pH were respectively, the most effective factors in the biosorption of thorium(IV). Under optimal conditions (pH 5, contact time 137.5 min, initial Th(IV) concentration 237.5 mg/l, and adsorbent dosage 1.63 g/l­) the capacity of the biosorbent for Th(IV) was estimated to be 128.82 mg/g. The kinetic data were fitted well the pseudo-second-order rate equation. The biosorption data could be well described by Langmuir isotherm in comparison to Freundlich and Temkin isotherms. The maximum sorption capacity of the biosorbent for Th­(IV), by Langmuir isotherm was estimated to be 142.86 mg/g. The thermodynamic parameters indicated that the biosorption of Th(IV) on the biomass was a spontaneous, and endothermic process, at the studied temperatures and would occur via physical adsorption.

Hierarchical zeolite was prepared from natural zeolite using tandem acid-base treatments and applied as adsorbent for Th(IV) removal. Natural zeolite occurred naturally as microporous material. It was modified using two familiar methods simultaneously, dealumination and desilication techniques, to change its micropore size into hierarchical pores.. Extensive characterization of both natural and modified zeolites were conducted using XRD, BET, SEM-EDS, and AAS. XRD Patterns of raw, pre-treated , and acid-base tandem modified zeolites show that the modification process has not changed the crystal properties of this material. However, the Si/Al ratio is increased from 6.688 to 11.401 for Na-zeolite (NaZ) and modified zeolite, ZA2B respectively. The surface area is increased from 125.4 m2/g (NaZ) to 216.8 m2/g (ZA2B), indicative of the creation of mesopore in addition to naturally micropore structure. The application of these zeolite materials as adsorbent were carried out using solution of 50 ppm Th4+measured using UV-Vis spectrophotometer. The UV-Vis result shows that the modified zeolite (ca. 10 mg) has higher adsorption capacity than natural zeolite. The adsorption process does not fit into Langmuir and Freundlich isotherm and the adsorption capacity of this material increase from 909 mg/g to 2000 mg/g for NaZ and ZA2B respectively.

Abstract: Delayed coincidence counters (RaDeCC), used for measuring 223Ra and 224Ra preconcentrated from water onto MnO2-impregnated acrylic fiber (“Mn-fiber”), require a standard Mn-fiber column that has a precisely known activity of 224Ra for calibration. This may be done by adding an aged 228Th standard solution to adsorb both 228Th and its daughter 224Ra quantitatively onto a Mn fiber. We used both seawater and deionized water (DIW) for testing the adsorption efficiency of Th and Ra onto Mn fibers. Our experimental results show that more than 50% of thorium (232Th and 228Th) breaks through the Mn-fiber column when DIW is used as a medium. However, near quantitative recoveries are obtained if filtered (0.45 μm) seawater is used to prepare the standard. In the case of pure DIW, the pH (initial pH∼5.3) rises to >10 after passing through the column while seawater (initial pH∼7.8) changes to ∼7.2. Thus, the lack of thorium adsorption in DIW may be attributed to this huge increase of pH and the consequent formation of Th(OH)4 and polyhydroxyl colloids. Based on these observations, we recommend that one should use either artificial seawater or natural seawater (which has negligible 224Ra and 228Th) as a loading solution after 0.45 μm filtration. In addition, the thorium adsorption efficiency should be confirmed either by thorium analysis of the effluent solution or long-term monitoring of the supported 224Ra on the Mn fiber using the RaDeCC. Similar cautions are likely necessary for making 223Ra standards by adsorption of 227Ac onto Mn fibers. [Copyright &y& Elsevier]

The cell-associated adsorption of thorium or uranium from the solution containing each metal only at pH 3.50 using various microorganisms was examined. Among the species tested, high thorium adsorption abilities were exhibited by strains of the gram-positive bacteria Arthrobacter nicotianae IAM12342, Bacillus megaterium IAM1166, B. Subtilis IAM1026, Micrococcus luteus IAM1056, Rhodococcus erythropolis IAM1399, and Streptomyces levoris HUT6156. And high uranium adsorption abilities were found in some gram-positive bacterial strains S. albus HUT6047, S. levoris HUT6156, and A. nicotianae IAM12342. Among these highly efficient thorium and uranium adsorbing microorganisms, S. levoris, which could adsorb the largest amount of uranium from the aqueous solution at pH 3.50, could adsorb about 383 μmol thorium and 390 μmol uranium per gram dry weight of microbial cells from the solution containing thorium or uranium at pH 3.50. The amount and time course of thorium adsorbed were almost unaffected by co-existing uranium; however, the adsorption of thorium was faster when carried out after the adsorption of uranium. Thorium adsorption also became faster when uranium was added after thorium adsorption. The effect of pH on thorium adsorption was also discussed. [ABSTRACT FROM AUTHOR]

The removal of radiotoxic Th4+ from aqueous solutions has been explored using two different groups of adsorptive materials (e.g. two activated carbons and four zeolites—two natural and two synthetic). The activated carbons were prepared from solvent extracted olive pulp (SEOP) and olive stone (OS) by a two-step physical activation method with steam. They were characterized by N2 at 77 K adsorption, Hg porosimetry and by determination of their iodine number. All carbons prepared are of the H-type (e.g. contain mainly basic surface oxides) confirmed by the results of the Boehm’s method. The natural zeolites, clinoptilolite (NaCLI) and mordenite (NaMOR), were pretreated with Na+ before the adsorption experiments, while the synthetic ones, NaX and NaA, were provided in their commercial sodium form.The natural zeolites, NaCLI and NaMOR, utilized 11.5 and 38.6% of the theoretical ion-exchange capacity, based on Al content, respectively, while NaX and NaA utilized 41.5 and 45.9%, respectively. The activated carbons showed better removal capability than NaCLI. NaMOR, showed comparable results to the carbon originated from OS, but lower removal capability than the carbon originated from SEOP. The synthetic zeolites showed the highest removal ability for thorium ions due to their increased ion-exchange capacity because of their cleaner and larger framework channels and their higher number of ion-exchange sites. The carbons adsorption capacity mainly depends on the content and nature of functional surface groups. The adsorption data were fitted to Langmuir and Freundlich models. The former achieved best fits and was further applied to obtain the respective Langmuir constant and maximum adsorption capacity for each system. [Copyright &y& Elsevier]

The adsorption of uranium from an acidic solution by microbes was examined. High uranium adsorption ability was exhibited by actinomycetes. Streptomyces levoris cells could adsorb about 380 μmol of uranium per gram dry cells from the solution. The cells could adsorb uranium over a wide acidic pH range and very rapidly. The amount of uranium adsorbed from a solution containing uranium and thorium was affected by the thorium concentration. The amount adsorbed was reduced and an uranyl–thorium ion exchange reaction occurred in the case of adsorption from a solution containing both metals. [Copyright &y& Elsevier]