Efficient Selective Adsorption of Rubidium and Cesium from Practical Brine Using a Metal-Organic Framework-Based Magnetic Adsorbent.

Rubidium (Rb) and cesium (Cs) have important applications in highly technical fields. Salt lakes contain huge reserves of Rb and Cs with industrial significance, which can be utilized after extraction. In this study, a composite magnetic adsorbent (Fe3O4@ZIF-8@AMP, AMP = ammonium phosphomolybdate) was prepared and its adsorption properties for Rb+ and Cs+ were studied in simulated and practical brine. The structure of the adsorbent was characterized by SEM, XRD, N2 adsorption-desorption, FT-IR, and vibrating sample magnetometer (VSM). The adsorbent had good adsorption affinity for Rb+ and Cs+. The Langmuir model and pseudo-second-order dynamics described the adsorbing isotherm and kinetic dates, respectively. The adsorption capacity and adsorption rate of Fe3O4@ZIF-8@AMP were increased by 1.86- and 2.5-fold compared with those of powdered crystal AMP, owing to the large specific surface area and high dispersibility of the adsorbent in the solution. The adsorbent was rapidly separated from the solution within 17 s using an applied magnetic field owing to the good magnetic properties. The composite adsorbent selectively adsorbed Rb+ and Cs+ from the practical brine even in the presence of a large number of coexisting ions. The promising adsorbent can be used to extract Rb+ and Cs+ from aqueous solutions.

Atmosphere- and Solvent-Controlled Coupling and Acetylation of Phenols Induced by Visible Light.

A tunable coupling or acetylation of phenol derivatives with diacetyl was enabled through the switch of the atmosphere and solvent induced by visible light under metal-free conditions. Symmetric and asymmetric diphenols or binaphthols were obtained under oxygen in water or 1,1,1,3,3,3-hexafluoroisopropanol, whereas phenol acetates were formed under argon in the presence of diacetyl and acetic acid. The possibility to control the chemo- and regioselectivities enriches the synthetic versatility of photoreactions.

Recent progress in photoinduced direct desulfurization of thiols.

The reduction of mercaptans plays an important role in diverse areas such as protein synthesis, polymer science, environmental study, and pharmaceutical chemistry. Despite significant advancements in this area, particularly in light-induced transformations, review articles have rarely been reported on this topic. Thus, this review article emphasizes the direct photoinduced desulfurization and functionalization of thiols to alkanes or coupling products, with a focus on significant advancements made in the last decade. The progress is discussed according to the types of bonds formed from the cleavage of Csp3-SH bonds.

Catalyst-free photo-reductions of aromatic olefins and carbonyl compounds.

We describe herein a catalyst-free, traditional reductant-free strategy for the direct photoinduced hydrogenation or deuteration of aromatic olefins, ketones, and aldehydes with simple bases as the only additives. A broad range of substrates were demonstrated with high yields and deuterium incorporations. Mechanistic experiments indicate a radical mechanism.

[Rapid Determination of Dodecylmorpholine in Aqueous Solutions with UV-Vis Spectrophotometry].

A rapid UV-Vis spectrophotometric method was proposed to determine the concentration of DMP in aqueous solutions. The linear concentration range of DMP solution at the range of 250～400 nm is 0.5～70 mmol·L(-1). At 275 nm, the linear fitting equation is A=0.030 7c+0.133 0 with a correlation of 0.980 9. The detection limitation is 9.46×10-5 mmol·L-1, the RSD (n=6) of the method were at the range of 0.100%～0.612%. The recovery ratio for salt solutions sample is 95%～104%. Temperature, pH, and coexisting K(+), Na(+), Mg(2+), Cl(-), Br(-), I(-), SO(2-)(4) ions do not affect the detection. The coexisting CO(2-)(3) and HCO(-)(3) ions can be eliminated with acidification. The results showed that the proposed method is simple in pretreatment process and has high accuracy and precision. It is a quick measurement method of DMP concentration in water solution, and can be used to measure DMP concentration in reverse flotation tail liquid and reverse flotation material pulp.

[Determination of Methyl Orange and Ethyl Orange in Two-Component Solution by Dual Wavelength Spectrophotometry].

The high similarity of MO and EO made it difficult to measure concentration of MOD and EOD. In this paper, dual wavelength spectrophotometry was used to determinate the concentration of MOD and EOD, which was proved to be fast and accrate. 429.00 nm and 469.50 nm were selected as detemination wavelengthes at pH 12. And the influences of Na+ and Cl- on determination of MOD and EOD were surveyed. The standard equations were A429 = 0.003 47 + 0.061 cm + 0.056 46 C(E) and A469.50 = 0.002 8 + 0.074 37 cm + 0.083 94 c(E) . Recovery of standard additions of MOD and EOD were larger than 95%, and relative standard deviation of standard equations were less than 2%. The addition of NaCl has little effect on recovery of standard additions and relative standard deviation of this method.

A Non-Bonding Interaction-Based Fluorescent Probe for Detection of Halogenated Carbonyl Compounds.

The fluorescent detection of neutral and volatile carbonyl halogenated compounds had not been studied before. We describe here a simple and sensitive turn-on rhodamin fluorescent probe for the selective detection of fluorinated/brominated/chlorinated/iodinated carbonyl compounds. A wide range of linear or cyclic volatile organic halides was detected with a limit of detection as low as 45.6 nM within 1 min. Mechanistic experiments and DFT calculations indicate the reversible formation of a 1:1 complex of sensor and analyst through non-bonding interaction.

Basic magnesium sulfate@TiO2 composite for efficient adsorption and photocatalytic degradation of 4-dodecylmorpholine in brine.

More than 70% of the potash fertilizer globally is produced by the froth flotation process, in which 4-dodecylmorpholine (DMP) serves as a reverse flotation agent. As the potash fertilizer production rapidly rises, the increased DMP levels in discharged brine pose a threat to the production of high-value chemicals. In this paper, composite particles of basic magnesium sulfate@TiO2 (BMS@TiO2) were prepared using a simple and mild loading method. These particles were utilized for the adsorption and photocatalytic degradation of DMP in brine. Compared with normal powdered materials, the granular BMS@TiO2 in this study can be easily separated from liquid, and the degradation intermediates will not enter the brine without causing secondary pollution. BMS@TiO2 consists of 5·1·7 phase (5Mg(OH)2·MgSO4·7H2O) whisker clusters embedding 2.3% TiO2. The adsorption equilibrium of DMP on BMS@TiO2 particles was achieved through hydrogen bonding and pore interception with the adsorption capacity of approximately 5 mg g-1 after 6 h. The photodegradation efficiency of DMP adsorbed on BMS@TiO2 reached about 92% within 16 h, which is compared with that of pure TiO2 nanoparticles. Additionally, excellent stability and recyclability of BMS@TiO2 were also observed in five cycle tests of adsorption and photocatalytic degradation of DMP, and the possible photocatalytic degradation pathways and mechanism of DMP are proposed following molecular electrostatic potential analysis. This work provides a sustainable and environmentally friendly approach for eliminating organic micropollutants from water environments.

Facet-dependent U(VI) removal of hematite with confined ferrous ions.

The presence of ferrous minerals has been demonstrated to have a significant impact on the destiny, migration, and availability of uranyl (U(VI)) in natural surroundings. The iron oxide/Fe(II) system is a multifaceted iron reduction system anchored to surfaces, encompassing various forms of iron and ferrous ions. Several studies have investigated the effectiveness of adsorbed ferrous iron on iron-based minerals to facilitate the reduction of heavy metal ions and radioactive nuclides. A range of techniques for characterization, including X-ray photoelectron spectroscopy (XPS) and Mössbauer spectroscopy, were employed to explore the process of U(VI) adsorption and deposition, focusing on the limited region containing ferrous iron on the exposed crystalline surface of hematite. In this specific investigation, two kinds of hematite nanocrystals primarily exposing {001} and {012} crystal facets, referred to as HNPs and HNCs, were synthesized. Their ability to remove U(VI) was examined. Ferrous ions (Fe(II)) adsorbed onto the surface of hematite nanocrystals significantly enhanced the efficiency of U(VI) remediation. Furthermore, the HNCs/Fe(II) system showed better U(VI) reduction ability than the HNPs/Fe(II) system. Remarkably, HNCs produced and consumed more electrons and hydroxyl radicals, indicating a more intense response. This finding serves to highlight the significance of their role in interfacial effects and in predicting the spatial distribution of U(VI) in aqueous systems.

[Determination of lithium in the oil field water by flame atomic absorption spectrometry].

Flame atomic absorption spectrometry was applied to the determination of micro amount of lithium in the oil field water of certain area. In order to determine which method is more appropriate for the determination of lithium content in the oil field water, standard curve method and standard addition method were compared. The effects of dilution, coexistent ions, and deionizers on the determination were studied. For the determination of lithium content in the same diluted oil field water samples, there exist obvious differences between the results obtained from standard addition method and standard curve method. Standard addition method gives results with a larger error, whereas standard curve method gives more accurate results. It is difficult to eliminate the interferences when the standard addition method is used. The standard curve method is found to be more suitable for the determination of micro amount of lithium in the oil field water for its accuracy, simplicity, and feasibility. When the standard curve method is used, both the determined lithium concentration and the recovery change with the dilution extent of the oil field water. In order to get an accurate result, the oil field water sample should be diluted to 1/200 or less. In this case, the recovery by standard addition method ranges from 94.3% to 96.9%. When sodium phosphate or sodium chloride is used as the deionizer, the recovery by standard addition method ranges from 94.6% to 98.6%, or from 94.2% to 96.3%. In the determination of lithium content in oil field water, there are larger experimental errors without the addition of any deionizer. When the concentration of coexistent ions is within an allowed range, the addition of sodium phosphate as a deionizer can eliminate the interferences of the coexistent ions with the determination of the lithium content. If sodium chloride is used as a deionizer, a more accurate result can be obtained when the sodium content in the samples is near the sodium content in the standard solutions. In general, under suitable experimental conditions, sodium chloride can be used as the deionizer for the determination of lithium content in the oil field water.

[Determination of rubidium and cesium in chloride type oilfield water by flame atomic absorption spectrometry].

Flame atomic absorption spectrometry (FAAS) was applied to the determination of rubidium and cesium in chloride type oilfield water by considering the interferences of the coexistent K+, Na+, Ca2+, and Mg2+ ions, Standard curve method and standard addition method were compared in the determination of rubidium and cesium in the simulated oilfield water and the real oilfield water from the Nanyishan region in Qaidam Basin. Although rubidium and cesium have similar physical-chemical properties, they present different characters during their analyses using the FAAS technique. When the standard addition method was used for the determination of rubidium and cesium in the simulated oilfield water, the results of rubidium were very poor, whereas the results of cesium were satisfactory. When the standard curve method was used for the determination of rubidium and cesium in the simulated oilfield water, the results of both rubidium and cesium were satisfactory within the linear ranges of the standard curves. For the real oilfield water, standard addition method is also only applicable for the determination of cesium with a recovery ranging from 90% to 110%. While standard curve method is applicable for the determination of both rubidium and cesium with a recovery ranging from 90% to 110%.

[Effect of octadecyl amine (ODA) on the complex titration of magnesium and calcium ions studied with UV-visible spectrophotometry].

The effect of flotation agent octadecyl amine (ODA) on the complex titration of both magnesium and calcium ions was studied with two groups of comparative experiments: (1) Before titration, the suspension was not filtered. In this case, ODA had a great effect on the complex titration of both magnesium and calcium ions. The titration end-point of magnesium ions was difficult to be determined. Although the titration end-point of calcium ions could be determined, there was an obvious experimental error compared with the blank solution without ODA. These results were confirmed by the UV-Visible spectrum analyses of the related solutions. (2) Before titration, the suspension was filtered. In this case, the influence of ODA on the complex titration of both magnesium and calcium ions could be removed. UV-Visible spectrum studies showed that, in this case, both the spectra and time scanning curves of the tested solutions were similar to those of the blank solutions.

Adsorption of boron by CA@KH-550@EPH@NMDG (CKEN) with biomass carbonaceous aerogels as substrate.

This research reports an innovative boron adsorbent of CA@KH-550@EPH@NMDG (CKEN) via the modification of N-methyl-d-glucosamine (NMDG) on the surface of biomass carbonaceous aerogel, which is environmentally friendly, economically inexpensive, has simple preparation process and good regenerability. SEM and FT-IR characterization results indicate that CKEN has a 3D cross-staggered structure with lots of hydroxyl groups and pore structure, which are beneficial to the diffusion of boron and the chelation interaction between boron and CKEN. The adsorption behavior of CKEN for boron was evaluated. Various parameters affecting adsorption properties, viz., pH, ionic strength, initial concentration of boron, temperature and contact time were investigated. The adsorption kinetics is fitted with pseudo-second-order kinetics model better and the adsorption of boron on CKEN is an exothermic process. The adsorption equilibrium reached within 15 h with the maximum adsorption amount of 1.42 mmol/g (298 K). Moreover, CKEN also showed excellent reusability by consecutive five cycles of adsorption-desorption. It can be used as a potential recyclable adsorbent for efficient enrichment of boron from aqueous solution.