Phosphate-rich cellulose beads for efficient cesium extraction from aqueous solutions: a novel approach for cellulose utilization.

In this work, phosphate-rich cellulose beads (CBPs) were first used for cesium extraction from aqueous solutions. These green, abundant, cheap, and renewable CBPs demonstrated a high adsorption capacity and fast absorption rate. Besides, the CBPs also exhibited excellent stability and recycling performance, as well as good selectivity. This study presents the promising application potential of cellulose for efficient cesium extraction from aqueous media.

Constructing porous ZnFC-PA/PSF composite spheres for highly efficient Cs+ removal.

Radioisotope leaking from nuclear waste has become an intractable problem due to its gamma radiation and strong water solubility. In this work, a novel porous ZnFC-PA/PSF composite sphere was fabricated by immobilization of ferrocyanides modified zinc phytate into polysulfone (PSF) substrate for the treatment of Cs-contaminated water. The maximum adsorption capacity of ZnFC-PA/PSF was 305.38 mg/g, and the removal efficiency of Cs+ was reached 94.27% within 2 hr. The ZnFC-PA/PSF presented favorable stability with negligible dissolution loss of Zn2+ and Fe2+ (< 2%). The ZnFC-PA/PSF achieved high-selectivity towards Cs+ (Kd = 2.24×104 mL/g) even in actual geothermal water. The adsorption mechanism was inferred to be the ion-exchange between Cs+ and K+. What's more, ZnFC-PA/PSF worked well in the fixed-bed adsorption (E = 91.92%), indicating the application potential for the hazardous Cs+ removal from wastewater.

Engineering a defect-rich Prussian blue analog composite for enhanced Cs+ removal performance.

Using a novel, irregular honeycombed N-doped porous carbon (NPC) as a support and defect inducer, defect-rich Zn-PBA was formed in situ and evenly anchored on the surface of NPC to obtain a defect-rich Zn-PBA/NPC composite. This composite demonstrated an ultrafast Cs+ adsorption rate that reached equilibrium within 60 s as well as excellent adsorption capacity, stability and reusability. The adsorption mechanism indicated that Cs+ was quickly adsorbed via the defect sites close to the Zn-PBA crystal face accompanied by K(OH2)+ elimination.

Novel Zr-Doped Thiostannate Spinning Fiber (Fiber-KZrTS) for Highly Efficient and Renewable Recovery of Cesium and Strontium from Geothermal Water.

The efficient and renewable recovery of cesium and strontium by absorption from a new type of geothermal water liquid mineral resource is highly desirable but still challenging. In this work, a new Zr-doped layered potassium thiostannate adsorbent (KZrTS) was first synthesized and used for Cs+ and Sr2+ green and efficient adsorption. It was found that KZrTS had very fast adsorption kinetics toward both Cs+ and Sr2+ with an equilibrium reached within 1 min, and the theoretical maximum adsorption capacities for Cs+ and Sr2+ were 402.84 and 84.88 mg/g, respectively. Moreover, to solve the loss problem of the engineering application of the powdered adsorbent KZrTS, KZrTS was uniformly coated with polysulfone by wet spinning technology to form micrometer-level filament-like absorbents (Fiber-KZrTS), whose adsorption equilibrium rates and capacities toward Cs+ and Sr2+ are almost the same as that of powder. Furthermore, Fiber-KZrTS showed excellent reusability, and the adsorption performance remained virtually unchanged after 20 cycles. Therefore, Fiber-KZrTS has potential application for green and efficient cesium and strontium recovery from geothermal water.

Highly selective and easily regenerated porous fibrous composite of PSF-Na2.1Ni0.05Sn2.95S7 for the sustainable removal of cesium from wastewater.

The removal of 137Cs from radioactive wastewater remains a huge challenge due to the interference of many coexisting ions. Several tin chalcogenides (X2Sn3Y7, XNa, K; YTe, Se, S) were synthesized and screened for highly selective cesium removal from radioactive wastewater. It was found that Na2Sn3S7 showed the best adsorption performance for low cesium concentrations. Especially after nickel doping, the adsorption capacity and thermal stability of the adsorbent were significantly enhanced. Its maximum adsorption capacity reached 436.72 mg·g-1 within only 5 min and adsorption performance kept active in the pH range of 2-12. After being coated with a porous polysulfone (PSF) fiber, the developed PSF-Na2.1Ni0.05Sn2.95S7 was applied to natural complex water with cesium concentration of 17.58 mg·L-1. The separation factors between Cs+ and competitive ions ranged from 625.21 to 13123.21. It is noteworthy that NaNO3 was an efficient regenerating agent and can be easily separated from the CsNO3 mixture for cyclic utilization. Remarkably, only 45 min in each cycle of adsorption and desorption toward cesium was realized, and the adsorption properties hardly decreased even after 50 consecutive cycles. The above advantages make the proposed material an excellent candidate for efficient Cs+ removal and enrichment from wastewater.

Cesium removal from wastewater: High-efficient and reusable adsorbent K1.93Ti0.22Sn3S6.43.

Efficient and quick removal of radioactive Cs+ from wastewater is significant for the safe use of nuclear energy and human health. A novel adsorbent K1.93Ti0.22Sn3S6.43 (KTSS) was developed for Cs+ removal from complex natural water systems. The working mechanism of KTSS for removing Cs+ was the synergistic effect of ion exchange and the Cs⋯S binding, which was proved by several characterization techniques. KTSS showed ultrafast kinetics for Cs+ adsorption within 1 min with a removal rate of 99%. Meanwhile, KTSS exhibited a higher adsorption capacity of 450.12 mg/g than many other adsorbents to remove Cs+ and possessed excellent chemical stability in a wide pH range of 3-12. Thanks to the natural affinity arising from the S2- ligands, KTSS displayed excellent selectivity for Cs+ even in different complex water systems. The separation factors between Cs+ and the coexisting ions of Na+, K+, Mg2+, Ca2+ were ranged from 408.61 to 7448.20. Fortunately, by eluting with NaNO3 the adsorbent could realize the green regeneration and cyclic utilization. Furthermore, it was found that KTSS had tremendous advantages in the removal of Cs+ in comparison with the other adsorbents. Consequently, it should be considered that KTSS obtained in this study has great potential in applying ultrafast and high-efficient removal of Cs+ from wastewater.

Volumetric properties of disodium dihydrogen pyrophosphate aqueous solution from 283.15 to 363.15 K at 101.325 kPa.

The purpose of this exploration was to determine the density and volumetric properties of the aqueous solution of Na2H2P2O7 with the molality varied from 0.08706 to 0.88402 mol·kg-1 measured at temperature intervals of 5 K from 283.15 to 363.15 K at 101.325 kPa using Anton Paar Digital vibrating-tube densimeter. The thermal expansion coefficient (α), apparent molar volume (VΦ), expansibility (ϕE), and partial molar volume (VB) of Na2H2P2O7 (aq) against temperature and molality have been evaluated from density data. On the basis of Pitzer ion-interaction apparent molar volume theory, the Pitzer single-salt parameters (ßM,X0v, ßM,X1v, ßM,X2v and CM,Xv, MX = Na2H2P2O7), and their correlation coefficients ai of the temperature-dependence formula f (i, p, T) = a1 + a2ln(T/298.15) + a3(T - 298.15) + a4/(620 - T) + a5/(T - 227) for Na2H2P2O7 were obtained for the first time. It was revealed that predicted apparent molar volumes agreed well with the experimental values indicating the single salt parameters and the temperature-dependent formula are reliable.

Prussian blue analogs-based layered double hydroxides for highly efficient Cs+ removal from wastewater.

In this work, novel Prussian blue analogs-based layered double hydroxide (PBA@ZnTi-LDH) was in situ synthesized and used for radioactive Cs+ removal from wastewater. The results suggested that this PBA@ZnTi-LDH prepared using LDH as skeleton and transition metal source showed higher adsorption capacity (243.9 mg/g) and water stability than conventional PBAs, and promising application in scale-up Cs+ removal. Thus, it was granulated by calcium alginate and the PBA@ZnTi-LDH/CaALG exhibited favorable post-separation and fixed-bed adsorption ability at different Cs+ concentrations and flow rates, highlighting its application perspective on Cs+ removal from various kinds of wastewater. Moreover, the real-world Cs+ removal was preliminarily explored using natural complex Cs+-containing water. As a result, this stable and easily separated PBA@ZnTi-LDH/CaALG showed high removal efficiency, selectivity and good reusability, which was promising in scale-up Cs+ removal from the real-world wastewater.

Enhanced kinetics and super selectivity toward Cs+ in multicomponent aqueous solutions: A robust Prussian blue analogue/polyvinyl chloride composite membrane.

Developing effective adsorbents for 137Cs removal from complex wastewater systems has been a significant challenge. Although existing spheres adsorbents could improve the post-separation ability and practical operability, the adsorption kinetics are still significantly retarded due to the large intra-particle diffusion resistance. Here, we demonstrate the efficiency of a robust Prussian blue analogue/polyvinyl chloride composite membrane (PPM), which was easily prepared by a simple solvent evaporation method. In virtue of the less dense layer and ion-sieving functionality, it showed enhanced kinetics (5 h) and super selectivity (SF = 248.3-5388.6) towards Cs+. New PPM was robust within a wide pH range (2-10) and exhibited favorable removal capacity (152.8 mg/g), placing it at an outstanding material for Cs+ removal among other adsorbents. Moreover, PPM could be simply eluted and reused using a KCl solution as eluent. A study of the adsorption mechanism confirmed an ion-exchange action during the removal process. Thus, PPM is considered to be a promising candidate for the removal of Cs+ from multicomponent aqueous solutions.

Thermodynamic and Dynamic Modeling of the Boron Species in Aqueous Potassium Borate Solution.

The concentration of B(OH)3, B(OH)4 -, B3O3(OH)4 -, and B4O5(OH)4 2- in the solution and the solubilities in the system KCl-K2SO4-K2B4O7-H2O and its subsystems were calculated on the basis of the Pitzer model. The mole fraction of the four boron species is mainly affected by m(B) in the solution but less by m(Cl-) and m(SO4 2-). m(Cl-) and m(SO4 2-) mainly affect the solubility of K2B4O5(OH)4·2H2O. The calculated solubilities in the system KCl-K2B4O7-H2O agree well with the experimental data. The results show that the standard chemical potentials of K2B4O5(OH)4·2H2O at 298.15 K obtained in this work is reliable. The transformation between the boron species at 298.15 K was also conducted with the density functional theory (DFT) method. The results affirm that the boron species can transform other boron species as the boron concentration in the solution changes.

Facile Synthesis of Porous Polymer Using Biomass Polyphenol Source for Highly Efficient Separation of Cs+ from Aqueous Solution.

In this work, a series of polyphenol porous polymers were derived from biomass polyphenols via a facile azo-coupling method. The structure and morphologies of the polymer were characterized by BET, TEM, SEM, XRD, TGA and FT-IR techniques. Batch experiments demonstrated their potentialities for adsorptive separation of Cs+ from aqueous solution. Among them, porous polymers prepared with gallic acid as starting material (GAPP) could adsorb Cs+ at wide pH value range effectively, and the optimal adsorption capacity was up to 163.6 mg/g, placing it at top material for Cs+ adsorption. GAPP exhibited significantly high adsorption performance toward Cs+ compared to Na+ and K+, making it possible in selective removal of Cs+ from ground water in presence of co-existing competitive ions. Moreover, the Cs-laden GAPP could be facilely eluted and reused in consecutive adsorption-desorption processes. As a result, we hope this work could provide ideas about the potential utilization of biomass polyphenol in environmental remediation.

Robust and recyclable sodium carboxymethyl cellulose-ammonium phosphomolybdate composites for cesium removal from wastewater.

A novel, facilely prepared, recyclable sodium carboxymethyl cellulose-ammonium phosphomolybdate composite (CMC-AMP) was synthesized by chemical cross-linking and used for Cs+ removal. The effects of adsorbent dosage, pH value, initial Cs+ concentration, contact time, temperature and competitive ions on adsorption were investigated. The results showed that CMC-AMP with good mechanical properties could effectively adsorb Cs+ in a wide pH range. In addition, the adsorption process of CMC-AMP was better fitted with the Lagergren first-second model and Langmuir isotherm model. Furthermore, CMC-AMP can be reused five times using ammonium chloride as the eluent without an obvious decrease in absorption activity. The results reveal that CMC-AMP can be used as a low cost and recyclable Cs+ adsorbent.

Heat Capacities and Thermodynamic Properties of Hungchaoite and Mcallisterite.

The heat capacities on two minerals of hungchaoite (MgB4O7·9H2O, Hu) and mcallisterite (MgB6O10·7.5H2O, Mc) have been measured with a precision calorimeter at temperatures ranging from 306.15 to 355.15 K, experimentally. It was found that there are no phase transition and thermal anomalies, and the molar heat capacities against temperature for the minerals of hungchaoite and mcallisterite were fitted as C p , m , Hu   =   - 27019.23675 + 229.55286 T   -   0.63912 T   2   +   ( 5.95862   ×   10   - 4 )   T   3 and C p , mMc   =   - 9981.88552   +   84.10964 T   -   0.22685 T   2   +   ( 2.0593   ×   10   - 4 )   T   3 , respectively. The molar heat capacities and thermodynamic functions of (HT-H298.15), (ST-S298.15), and (GT-G298.15) at intervals of 1 K for the two minerals were obtained for the first time. These results are significant in order to understand the thermodynamic properties of those minerals existing in nature salt lakes, as well as applying them to the chemical engineering process design.

Speciation analysis of arsenic in samples containing high concentrations of chloride by LC-HG-AFS.

Chloride widely exists in the environment and will cause serious interference for arsenic speciation analysis. The determination of four arsenic species including arsenite (As(III)), arsenate (As(V)), monomethylarsenate (MMA), and dimethylarsonate (DMA) in samples containing high concentrations of Cl- was carried out in this work by coupling of liquid chromatography (LC) with hydride generation atomic fluorescence spectrometry (HG-AFS). The interference of Cl- was successfully eliminated by coupling two anion-exchange chromatographic columns in series and eluting with 35.0 mmol L-1 (NH4)2HPO4 (pH = 6.00). A novel pre-treatment system was subsequently developed to realize on-line column switch and pre-reduction of As(V). The analysis time was shortened by an isocratic elution but programmed flow rate method, and the sensitivity of As(V) was also enhanced by the introduction of pre-reduction using the developed system. The proposed method can resist at least 10 g L-1 Cl- without any pre-treatment operations. Since LC-HG-AFS is low-cost and can be afforded or self-assembled by most labs, the developed method can be adopted as a routine analysis method for arsenic species in chloride-bearing samples, such as urine and seawater. Graphical abstract.

Synthesis of Polyporous Ion-Sieve and Its Application for Selective Recovery of Lithium from Geothermal Water.

The widespread use of lithium-ion batteries has led to continuously increasing demands for lithium. In order to recover lithium from geothermal water, a novel composite lithium ion-sieve was synthesized and applied in this work. The stability of the material was successfully solved by granulating using acid-alkali resistant polyvinyl chloride as a binder, and its adsorption performances were also improved by using polyethylene glycol (PEG-6000) as a porogen to obtain a polyporous structure. When the developed material was applied for lithium separation from geothermal water, the adsorption capacity reached 12.84 mg/g at 328.15 K with an equilibrium time of about 12 h. The material can be well regenerated using 0.25 mol/L HCl to realize cycle use. The separation factors between Li+ and other co-existing ions were within the range of 273.58-521.28, and the attenuation of adsorption capacity after five cycles was no more than 2%. The high selectivity and reusability properties of the polyporous ion-sieve make the material a potential candidate for the selective separation and recovery of a low concentration of lithium from geothermal water.

Arsenic Species Analysis at Trace Level by High Performance Liquid Chromatography with Inductively Coupled Plasma Mass Spectrometry.

A sensitive and accurate simultaneous continuous analysis for six arsenic species including arsenobetaine (AsB), arsenocholine (AsC), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenite (AsIII), and arsenate (AsV) has been developed by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). An anion-exchange column of Hamilton PRP-X100 (Switzerland) was applied for separation of the six arsenic species with gradient elution of 1.25 mmol/L Na2HPO4 and 11.0 mmol/L KH2PO4 as the mobile phase A and 2.5 mmol/L Na2HPO4 and 22.0 mmol/L KH2PO4 as the mobile phase B. The linearity ranges for AsB, AsC, MMA, DMA, AsIII, and AsV were between 0.5 and 50.0 µg/L, and the detection limits of the six arsenic species were all within 0.01-0.35 ng/L. The relative standard deviations (RSDs) were within 2.26-3.68% and the recovery rates of samples ranged from 95 to 103%. The proposed method was applied for the arsenic speciation analysis of sediment pore-water samples, which were taken from the supernatant after centrifugation and filtration.

Speciation Analysis of Trace Arsenic, Mercury, Selenium and Antimony in Environmental and Biological Samples Based on Hyphenated Techniques.

In order to obtain a well understanding of the toxicity and ecological effects of trace elements in the environment, it is necessary to determine not only the total amount, but also their existing species. Speciation analysis has become increasingly important in making risk assessments of toxic elements since the toxicity and bioavailability strongly depend on their chemical forms. Effective separation of different species in combination with highly sensitive detectors to quantify these particular species is indispensable to meet this requirement. In this paper, we present the recent progresses on the speciation analysis of trace arsenic, mercury, selenium and antimony in environmental and biological samples with an emphasis on the separation and detection techniques, especially the recent applications of high performance liquid chromatography (HPLC) hyphenated to atomic spectrometry or mass spectrometry.

Composite hydrogel particles encapsulated ammonium molybdophosphate for efficiently cesium selective removal and enrichment from wastewater.

A novel ammonium molybdophosphate (AMP)/ polyvinyl alcohol (PVA)/ sodium alginate (SA) composite hydrogel (APS) was prepared for Cs+ removal and enrichment from radioactive wastewater. Batch experiments with the subject of AMP concentration, pH value, initial Cs+ concentration, contact time, temperature, competing ions were investigated. The results showed this APS hydrogel with high permeability and stability could effectively adsorb Cs+ at widely broad pH value range and low Cs+ concentration within a short time. Adsorption thermodynamic parameters indicated the endothermic and spontaneous nature of the adsorption process, and the Lagergren pseudo-second order model was found to exhibit the best correlation with the adsorption results. Equilibrium data was better described by the Langmuir isotherm equation, and the maximum adsorption capacity of APS hydrogel calculated was in consistent with the experimental results. Furthermore, the APS hydrogel could be easily reused at least five times without obvious decrease in absorption activity and selectivity using ammonia nitrate as the eluent, and what's more, the Cs+ concentration in eluent was approximately concentrated for 2 times after single cycle. All the results suggest that the environmental friendly and low-cost APS hydrogel could be used as effective and selective material for Cs+ removal and enrichment from wastewater.

Species and correlations between selenium and mercury in fishpond ecosystems.

The chemical species and contents of selenium and mercury in water, sediments, and crucian carps collected from three wild and three aquaculture fishponds in Tianjin, China, were determined, and the interaction between selenium and mercury in water was also investigated by the calorimetry method. The results revealed that the average contents of total selenium (TSe) and total mercury (THg) in each item of the wild areas were higher than in those of the aquaculture areas, and significant differences (95% confidence) were presented for THg both in the sediments and crucian carps. The molar ratios between TSe and THg in all investigated fishponds were far higher than 1, indicating good protective effects of selenium on mercury toxicity. Obviously, negative correlations (r > 0.9993) were found between TSe and THg in water. The antagonism of selenium on mercury in water was confirmed to mainly result from the reaction between selenate and Hg2+ to form an insoluble selenium-mercury oxygenated compound, by which the addition of selenate into the water of fishponds would reduce the environmental risk of mercury. PRACTITIONER POINTS: Se and Hg in different fishpond ecosystems were investigated and compared. Direct evidence was provided for the interaction between Se and Hg in water. The addition of Se(VI) into fishpond ecosystems would reduce the environmental risk of Hg.

Basic Salt-Lake Brine: An Efficient Catalyst for the Transformation of CO2 into Quinazoline-2,4(1 H,3 H)-diones.

The efficient transformation of CO2 into value-added chemicals with green, abundant, and cheap catalysts is an interesting and challenging topic in both green and sustainable chemistry. In this study, a series of salt-lake brines were used for the first time to catalyze the reaction of CO2 and a broad range of 2-aminobenzonitriles to form the corresponding quinazoline-2,4(1 H,3 H)-diones. It was found that the abundant, available, and inexpensive Zhabuye basic salt-lake brine could efficiently promote the reaction of 2-aminobenzonitriles under low pressure of CO2 . Very high yields of value-added products were obtained. Further studies indicated that the basic carbonate and borate ions in the brine play key roles in accelerating the reactions.