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A mesoporous adsorbent was synthesized within a short time by a microwave-assisted method, and it showed high capacity and reusability for Pb(ii) adsorption.

Hollow red cell-like Na2Ti3O7/nitrogen-doped carbon are synthesized by a template-self strategy.

A novel preparative approach for promising cathode materials for capacitive deionization (CDI) is proposed. Several 3D Na4Ti9O20/N-doped carbon composite materials (3D NTO/N-C-x, x represents the hydrothermal reaction time) with high surface area are synthesized by pyrolysis of Ti-based metal–organic frameworks (Ti-MOFs) and a subsequent hydrothermal treatment strategy. Notably, the intrinsic interfacial interaction of the optimized 3D NTO/N-C-2 facilitates the synergy of the internal driving field and condensed phase interface, which is greatly beneficial to obtain more active sites for sodium ion storage and improved storage capacity (249 F g−1 at 1 A g−1). Furthermore, an all-faradaic-type 3D NTO/N-C-2//Ag@rGO full desalination cell shows high salt adsorption capacity (59.3 mg g−1) and stable cycling desalination ability (95% capacity retention rate over 20 cycles at 1.4 V). In addition, the mechanism of the zwitterion removal/release of the desalination cell is thoroughly investigated by electrochemical measurement. This work not only provides a reasonable strategy to establish cathode materials for CDI, but also may trigger the rapid development of Ti-based electrode materials in many frontier fields.

BACKGROUND: Persimmon tannin, extracted from young astringent persimmons, is a cheap waste biomass material. The abundant phenolic hydroxyl groups in persimmon tannin are known to display excellent affinity to Mo(VI). In addition, ligands containing N donor atoms, as brilliant adsorption groups, can strongly interact with Mo(VI) when the groups are protonated under acidic conditions. Therefore, the introduction of nitrogen‐containing groups in persimmon tannin may be an effective method to improve the recovery capacity of biosorbent for Mo(VI) in aqueous solution. In this work, a series of adsorbents were prepared by immobilizing ethylenediamine or methylamine on the surface of persimmon tannin. RESULTS: Due to the abundant nitrogen‐containing groups and hydroxyl groups, the ethylenediamine modified persimmon tannin exhibited excellent maximum uptake capacity to Mo(VI) (478.02 mg·g⁻¹), which was superior to that of methylamine modified persimmon tannin. Further, the results of XPS and FT‐IR confirmed that Mo(VI) was adsorbed on the hydroxyl‐assisted nitrogen‐containing group modified persimmon tannin via coordination and electrostatic interaction. CONCLUSION: Furthermore, 99% of Mo(VI) was selectively recovered from coexisting ions by en‐CPT under appropriate acidic conditions (pH 1). Pseudo‐second‐order kinetic model best represented the adsorption process of Mo(VI) onto the en‐CPT. The adsorption equilibrium was achieved in a relatively short time (no more than 1 h). High recovery efficiency and excellent selective adsorption made the en‐CPT an ideal candidate for Mo(VI) recovery in practical applications. © 2020 Society of Chemical Industry (SCI)

Herein, a thiourea cross-linked three-dimensional graphene aerogel (TCGA-1) was successfully prepared via a ring-opening reaction between the amino groups of thiourea molecules and the epoxy groups of graphene oxide (GO) sheets. Honeycomb-like three-dimensional porous morphology was confirmed by SEM, TEM, TGA, FT-IR, XPS, RS and XRD. The removal of heavy metal ions (Cu2+, Pb2+, Cr3+ and Cd2+) onto TCGA-1 was investigated with respect to solution pH, metal ion concentration and cycle time. In addition, it was also developed for the removal of anionic dyes (acid orange II and methyl orange) and cationic dyes (rhodamine B, methylene blue, and malachite green) from water. The results indicate that the removal of heavy metal ions onto TCGA-1 was greatly influence by pH. The sample can be regenerated more than twenty times based on their adsorption/desorption cycles, with a slight loss in the removal capacity. Malachite green or methylene blue (100 mg L−1) was completely removed using TCGA-1 within six hours and the removal behavior was described well using a pseudo-second-order kinetic model. It is also effective for removing other organic dyes used in this work. Therefore, the prepared broad-spectrum adsorbent exhibits satisfactory performance for many kinds of contaminants, suggesting its potential applications in the environmental cleanup.

In order to enhance the catalytic performance of the Gd-modified Co

Herein, a new persimmon tannin/graphene oxide (GO-PT-6Glu) composite was fabricated through one-step cross-linking method. The as-prepared GO-PT-6Glu has substantial phenolic hydroxyl groups (up to 5.23 mmol g−1) by introducing water-soluble PT (up to 5.50 mmol g−1) on the GO, which provides the opportunity to use it as an adsorption material to recover germanium. The GO-PT-6Glu was then used to adsorb germanium from aqueous solution and showed the highest than among currently reported adsorption capacity (117.38 mg g−1). Simultaneously, it exhibits excellent cycle performance to adsorb germanium still with a high adsorption efficiency (up to 81.42%) after 5 adsorption–desorption cycles. More importantly, the GO-PT-6Glu showed superior selectivity towards Ge(IV) as compared to As(III) (Cl−/SO42−/PO43−), in spite of the concentration of As(III) (Cl−/SO42−/PO43−) was 100 times higher than that of Ge(IV). Taking advantages of its low cost, selective adsorption, as well as environmental protection and high adsorption, the GO-PT-6Glu is expected to be the most promising material in recovery of Ge(IV) from water containing As(III).

In the present work, high density active sites (C N– groups) were introduced favorably onto the surface of silica by cross-linking reaction, leading to designing a new adsorbent and applying to the adsorption for Re(VII) from aqueous solutions. The novel adsorbent (SS-0.5h-0.5N-15GA) was characterized by SEM-EDS, TEM, FT-IR and XPS etc. The adsorption process fitted well with Langmuir isotherm the kinetic data fitted with pseudo-second order, and the experimental maximum adsorption capacity for Re(VII) was 270.13 mg/g at pH3.0, which was much higher than SS-0.5h-0.5N. Significantly, the reusability experiments demonstrated that SS-0.5h-0.5N-15GA exhibited excellent regeneration ability, with no obvious decline in adsorption capacity after four cycles. These results indicated that SS-0.5h-0.5N-15GA were promising for Re(VII) adsorption because of their higher rhenium adsorption capacity, rapid adsorption rate, low cost, and facile recovery process.

Diethanolamine functionalized cellulose based on rice husk (DEA-EPI-RH) was prepared to separate gallium ions from As(III) or/and Ge(IV) mixtures. The contents of hydroxyl functional group in the DEA-EPI-RH were up to 1.48 mmol g−1, and the maximum adsorption capacity for Ga(III) achieved to 130.44 mg g−1. The adsorption mechanism depended on the ion exchange of Ga(OH)2+, Ga(OH)2+, or Ga3+ with trihydroxy hydrogen on the surface of the DEA-EPI-RH. The DEA-EPI-RH showed superior selectivity with high adsorption capacity towards gallium as compared to As(III) or/and Ge(IV) with several times higher than concentration of Ga(III). Furthermore, the excellent reusability of the DEA-EPI-RH were confirmed by the desorption and regeneration experiments. The studied adsorbent was deemed to be promising, environment-friendly and low-cost materials to recovery of gallium from aqueous solution containing As(III) or/and Ge(IV).

Imidazolium-based ionic liquids (ILs) are a promising candidate for efficient separation of radioactive pertechnetate (TcO

Imidazolium-based ionic liquids (ILs) are a promising candidate for efficient separation of radioactive pertechnetate (TcO4-) from nuclear waste. However, their effective fixation, availability of active sites and slow adsorption kinetics remain challenges. Here, we incorporated the bisimidazolium-based ILs into porous metal-organic frameworks (MOFs) via a combination of immersion grinding and in-situ polymerization. 3,3′-divinyl-1,1′(1,4-butanediyl) diimidazolium dichloride is tightly bound inside and outside the porous MOFs matrix by uniform immersion grinding, which facilitates the exposure of more adsorption sites and provides channels for the anions to travel through quickly. Solvent-free polymerization reduces environmental pollution and energy consumption. Notably, the composite P[C4(VIM)2]Cl2@MIL-101 possesses an admirable removal efficiency (673 mg g−1) compared with the pristine poly(ionic liquid)s (215 mg g−1). Meanwhile, it exhibits fast sorption kinetics (92% in 2 min), good β and γ radiation-resistance, excellent regeneration and eminent removal efficiency in high alkaline conditions (83%). These superior traits endow that P[C4(VIM)2]Cl2@MIL-101 effectively separated TcO4- from simulated Hanford Low-activity Waste (LAW) Melter off-gas scrubber solution tested in this work. DFT density functional theory confirms that the strong electrostatic attraction and minimum Gibbs free energy (−6.2 kcal mol−1) achieve high selective adsorption for TcO4-. P[C4(VIM)2]Cl2@MIL-101 demonstrates the considerable potential to remove TcO4- from radioactive contaminants.

In order to replace extractant or resin prepared from petrochemical products, a series of carboxyl-functionalized materials based on natural corn stalk (x-IDA-EPI-OCS) were prepared. When the mass ratio of the EPI-OCS and iminodiacetic acid (IDA) was 1:3, the uptake capacity of Ga(III) on the modified corn stalk (3-IDA-EPI-OCS) from acidity solution could react 139.56 mg g−1. More importantly, the 3-IDA-EPI-OCS could completely separate Ga(III) from Ga(III)–As(III) or/and Ga(III)–Ge(IV) binary mixtures at pH > 2. By analyzing the results of acidity test as well as that of FTIR and XPS, the adsorption mechanism was deduced as cation exchange between Ga3+, Ga(OH)2+or Ga(OH)2+ and the hydrogen ions of carboxyl groups and/or hydroxyl groups. This study provided an effective and economical method for recovery of gallium ions from aqueous solution.

A renewable and recyclable adsorbent was synthesized by introducing thiol ( C SH), episulfide (C S C ring) and thion ( C S) groups onto the surface of corn stalks with epithiochlorohydrine as a crosslinker (OCS-ET-TU). The adsorption capacity of OCS-ET-TU for [AgCl4]3− reached to 79.94 mg∙g−1 at the acid concentration of 1.0 mol∙L−1 when the concentrations of Cu(II) and Ni(II) all reached to 10,000 mg∙L−1; the maximum selectivity coefficients of the OCS-ET-TU for Ag(I)/Cu(II) and Ag(I)/Ni(II) achieved to 2.95 and 3.37, respectively. The FT-IR and XPS results showed that [AgCl4]3− as soft acid could easily interact with the sulfur-containing groups belonging to the OCS-ET-TU as soft base. The adsorption and regeneration results of corn stalk-based OCS-ET-TU presented that it can potentially apply for recovery of trace amount of silver anions. The investigation provides a new and high-efficient biomaterial to enrich Ag(I) from nickel electrolyte with high concentrations of copper, iron and nickel.

Rhenium (Re) is a rare element in the earth’s crust and has wide range applications in industry, its effective secondary enrichment plays a crucial role in environment and energy field. On the basis of economy and resource sustainability, we report a facile and rapid process to prepare chitosan (CS) functionalized mesoporous silica composites for recovery of Re by a one-pot microwave-assisted synthesis method. Schiff base groups inside the nanostructure were functioned as active sites for Re adsorption. A series of characterization analysis indicated that the optimal adsorbent (SS-KIT-6-M4-15-CS3) possessed mesoporous channel and retained the ordered morphology of mesoporous silica skeleton. The maximum adsorption capacity for Re(Ⅶ) of the as-prepared adsorbent reached 261.81 mg·g−1 at pH 4, higher than that of other reported adsorbents. The SS-KIT-6-M4-15-CS3 showed excellent regeneration performance after eight adsorption–desorption cycles, and exhibited high selectivity for Re(Ⅶ). The prominent adsorption performance was attributed to the chelation between C = N and ReO4¯ according to FT-IR and XPS analysis. These findings showed encouraging potentiality of the adsorbent for recovering of Re(Ⅶ) in real industrial effluents.

A series of xwt%Al-SBA-15 catalysts prepared by modified wetness impregnation was investigated for γ-valerolactone (GVL) decarboxylation to butene. It was found that the impregnation of Al species not only remained the ordered mesoporous structure of parent SBA-15, but also created large amounts of Bronsted and Lewis acid sites on the surface of catalyst. The considerable amount of solid acid sites and the suitable Bronsted/Lewis acid ratio endowed 2.23 wt%Al-SBA-15 catalyst an excellent catalytic performance. Under the optimized conditions, the GVL conversion and butene yield can reach 99.8% and 96.6% at 320 °C, respectively. Mechanism studies indicated that the decarboxylation of γ-protonated PEA controlled speed of the whole reaction. Moreover, the catalytic activity of regenerated 2.23 wt%Al-SBA-15 catalyst was satisfactory after eight cycle tests, and the butene yield could still reach 92.2%.

Reported powdery adsorbents with poor adsorption efficiency and stability make it imperative to develop novel materials to extract gallium ions (Ga(III)) from effluents. Herein, UiO-66-NH2-based mixed matrix membranes (TPU/0.1THB/U6N-1.5 MMMs) via electrospinning is firstly reported for separation and recovery of Ga(III). TPU/0.1THB/U6N-1.5 MMMs efficiently overcomes multiple bottlenecks of powder UiO-66-NH2, including poor stability, reusability and adsorption capacity. Its maximum adsorption for Ga(III) is 96.18 mg·g−1 at pH 10.0. It has superiority in selective adsorption of Ga(III) from Al(III), Cu(II), Zn(II), Co(II) coexistence solution. Adsorption capacity of TPU/0.1THB/U6N-1.5 for Ga(III) reaches more than 80% after 9 cycles. Specially, it still retains excellent mechanical strength, flexibility and structural integrity after 12 h filtration, or after 9 adsorption-desorption cycles, even soaked in 5 mol·L-1 HCl for a week. TPU/0.1THB/U6N-1.5 MMMs also improves the problem of low water flux. TPU/0.1THB/U6N-1.5 with high MOFs loading possess high water flux of 382.2 L·m−2·h−1 with a permance of 382.2 L·m−2·h−1·bar−1 and rejection rates of 90% for Ga(III). The main adsorption mechanism of TPU/0.1THB/U6N-1.5 is based on the chelation between phenolic hydroxyl groups of MMMs and Ga(III) at pH 10.0. Overall, the as-prepared TPU/0.1THB/U6N-1.5 has potential for water treatment through the process of membrane adsorption.

99Technetium (99Tc) is one of the most dangerous radioactive isotopes in the legacy nuclear waste, and harmful to the environment and human health. Effectively removing it remains a long-term challenge. Herein a resin-like imidazolium-based ionic liquid polymer (DVB-2C8VEIMBr) was prepared for selective adsorption of TcO4− (ReO4− as an alternative for laboratory operation). It is manifested that DVB-2C8VEIMBr integrates high adsorption capacity (313.28 mg·g−1) and selectivity (90.68% in 6000 times excess of SO42− ions). A real-scenario experiment exhibits DVB-2C8VEIMBr can remove up to 93% of TcO4− from the simulated Hanford LAW scrubber solution. More importantly, DVB-2C8VEIMBr displays super acid and alkaline resistance and stability after immersing for 8 months under extreme conditions of 3 M HCl and 2 M NaOH. It can also effectively separate rhenium from molybdenum solution in the range of 3 M HCl - pH 2. Additionally, it still showed perfect regeneration performance after 10 cycles. In particular, this work demonstrates the feasibility of imidazolium-based ionic liquid adsorbents in the TcO4− or ReO4− immobilization process, which can be applied to capture these radioactive oxygen anions under high acid and high alkali conditions.

Iron hydroxide/manganese dioxide doped straw activated carbon was synthesized for As(III) adsorption. The Fe-Mn-SAc adsorbent has two advantages, on the one hand, the straw active carbon has a large surface area (1360.99 m2 g−1) for FeOOH and MnO2 deposition, on the other hand, the manganese dioxide has oxidative property as a redox potential of (MnO2 + H+)/Mn2+, which could convert As(III) into As(V). Combined with the arsenic species after reacting with Fe-Mn-SAc, the As(III) transformation and adsorption mechanism was discussed. H2AsO4−oxidized from As(III) reacts with the Fe-Mn-SAc by electrostatic interaction, and unoxidized As(III) as H3AsO3 reacts with SAc and/or iron oxide surface by chelation effect. The adsorption was well-described by Langmuir isotherms model, and the adsorption capacity of As(III) was 75.82 mg g−1 at pH 3. Therefore, considering the straw as waste biomass material, the biosorbent (Fe-Mn-SAc) is promising to be exploited for applications in the treatment of industrial wastewaters containing a certain ratio of arsenic and germanium.

Extraction of rhenium into the ionic liquids phase from aqueous solutions was investigated using N235 as extractant. At temperatures from 293.15 to 318.15 K, the equilibrium molalities of ReO4– were measured at an ionic strength from 0.2 to 2.0 mol·kg–1 in the aqueous phase containing NH4Cl as supporting electrolyte. The standard extraction constants K0 at various temperatures were obtained by methods of the Pitzer polynomial approximation. Thermodynamic properties for the extraction process were calculated.

This study described the synthesis of the Mo(VI)-imprinted ethylenediamine (EDA) grafted chitosan (I-EDA-CS), which is a novel technique in combination with surface imprinting and polymer crosslinking. Results indicated that mass ratio of ammonium molybdate and chitosan as 1 g:25 g–3 g:25 g could be conducive to achieve higher adsorption capacity of Re(VII). The maximum adsorption capacity of Re(VII) was found to be 418.98 mg·g −1 at 303 K with an initial Re(VII) concentration of 500 mg·L −1 , while maximum adsorption of Re(VII) on the non-imprinted absorbent (N-EDA-CS) was just 83.92 mg·g −1 . The maximum selectivity coefficients of the I-EDA-CS for Re(VII)/Cu(II), Re(VII)/Zn(II), Re(VII)/Mn(II), Re(VII)/Fe(II) were 1.29, 1.9, 2.31, 1.81, respectively. It revealed that the Mo(VI)-imprinted adsorbent showed superior selectivity and affinity to Re(VII) in case of the existence of competition ions. The analysis results of FT-IR and XPS confirmed that the high adsorption selectivity of the I-EDA-CS attributed to the chelation and electrostatic attraction between the amine groups and Re(VII) anionic complexes in the “cavities”. Imprinted I-EDA-CS was successfully employed for the selective adsorption of Re(VII) from industrial wastewater.

A series of ionic liquids based on trifluoroacetic acid, namely, [Cnmim][TFA] (n = 2, 3, 4, 5, 6) (1-alkyl-3-methylimidazolium trifluoroacetate), were designed and synthesized. The density, surface tension and refractive index were measured in the temperature range of 293.15 to 343.15 ± 0.05 K, and some physicochemical properties of the ILs were calculated. Using the concept of molar surface Gibbs free energy, the traditional Eotvos equation was improved into a modified Eotvos equation, in which the intercept and the slope represented the molar surface enthalpy and the molar surface entropy, respectively, for [Cnmim][TFA] (n = 2, 3, 4, 5, 6). The thermal expansion coefficient (α) of [Cnmim][TFA] was calculated according to the interstitial model, and the order of magnitude of the calculated values was in good agreement with the corresponding experimental values. A new hypothesis was proposed, stating that the interstitial molar surface Gibbs free energy (gs) is not determined by the type of IL. From the refractive index and the molar surface Gibbs free energy, an equation to predict the surface tension of ILs was derived and the predicted values were highly correlated with the corresponding experimental values. Finally, a new polarity scale for ILs was developed, and the polarity order of the [Cnmim][TFA] (n = 2, 3, 4, 5, 6) ILs was estimated.

Graphene oxide (GO) has great potential in metal recovery and water purification owing to their high surface area, abundant hydroxyl ( OH) and carboxyl ( COOH) groups. To fully understand the influence of the dispersity of GO on the adsorption capacity of metal ions, a series of polyacrylic acid (PAA) functionalized GO (PAA/GO) composites with different dispersity were prepared. The charge density of the PAA/GO composites were much higher than that of the untreated GO in acidic conditions, demonstrating a significant improvement of dispersibility by introducing PAA on the surfaces. Moreover, recovery of gallium by employing the PAA/GO composites as adsorbent were studied. The maximum adsorption capacity towards gallium ions of the adsorbent can reach 196.84 mg·g−1, much higher than that of other commercially available resins (CL-P204, P507). This superiority could be attributed to the abundant COOH groups on the surfaces and the good dispersity of the PAA/GO composites. These results revealed that the PAA/GO composites could be promising adsorbents for selective adsorption and efficient recovery of Ga(III).

We prepared a series of amino-functionalized organic-inorganic hybrid silica materials by post-modification (SBA-15-N) and one-pot (SS-0.5h-N) methods with different molar rate of APTES/SS (0.1:1, 0.2:1, 0.3:1, 0.5:1), and then took salicylaldehyde and epichlorohydrin as bridges, modified diisobutylamine on the hybrid silica to obtain the adsorbents containing tertiary amine groups. It was found that the combined use of organic and inorganic precursors (one-pot) destroys the ordered mesoporous structure, but the organic units distributed more homogeneously which conducive to the progress of adsorption. For the samples prepared by one-pot, the adsorption capacity increased dramatically when the molar rate of APTES/SS is 0.3:1 (SS-0.5h-0.3N-DIBA, 221.37 mg g−1), and the adsorption behavior obeys the Langmuir model. The adsorption mechanism could be electrostatic attraction and chelation effect between ReO4− and nitrogenous group which demonstrated by FT-IR and XPS. In addition, the SS-0.5h-0.3N-DIBA could effectively separate Re(VII) from coexisting metal ions (Cu(II), Zn(II), Mn(II)) at pH

In this study, we synthesized a series of diisobutylamine-functionalized graphene oxides as adsorbents (GO-DEA-DIBA) by adjusting synthetic conditions for the efficient adsorption of rhenium(VII) (Re(VII)). Results indicated that the best mass ratio was 10 mg of sodium carbonate to 5 g of distilled water, and a cooling time of 44 min could prevent the exfoliation of functional groups and achieve higher uptake capacity of Re(VII). The maximum uptake of Re(VII) was found to be 140.82 mg g–1 at 303 K with an initial Re(VII) concentration of 800 mg L–1. More importantly, it can be clearly seen that mixed ions (Cu2+, Zn2+, and Mn2+) could almost separate with Re(VII) on the adsorption of ReO4– onto the GO-DEA-DIBA with a weak acidity solution. Re(VII) was adsorbed on the GO-DEA-DIBA via charge interactions between tertiary amine groups and ReO4– by infrared spectroscopy and X-ray photoelectron spectroscopy analysis. In addition, adsorption behavior, adsorption isotherms, desorption, and regeneration are also d...

High sulfur content is one of the many challenges in processing the refractory bauxites of China. A new method to prepare Al2O3 from high-sulfur bauxite with the NH4HSO4 roasting process was studied. The paper offers a possible alternative method for desulfurization of bauxite that may improve overall process economics and environmental impact. The roasting mechanism and various parameters including the amount of the ammonium bisulfate addition, roasting temperature and roasting time were investigated. The results showed that the control step of the roasting process was chemical control and the apparent activation energy was 65.74 kJ/mol over the reaction temperature range from 623 to 648 K. The leaching kinetics of the sintered clinker by water was investigated, which was affected by temperature, mass ratio of liquid to solid and time. Analysis of the kinetic data indicates that the dissolution of bauxite ore was controlled by the shrinking core with surface reaction model. The apparent activation energy of the leaching process was found to be 37.94 kJ/mol from 323 to 363 K. The maximum aluminum dissolution ratio reaches about 93% under the optimal condition. This paper aims at giving some revelation and instruction for the further research and practice on high sulfur bauxites development and application.

In the present work, the extraction of Re(VII) from hydrochloric acid solution by N263/TBP/n-heptane/NaCl microemulsion was studied. In the extraction system, methyl trioctylammonium chloride (N263) bears double functions as a surfactant and an extractant. The extraction mechanism of Re(VII) by N263/TBP/n-heptane/NaCl was anion-exchange and complexation, and the extracted species could be referred as R 3 CH 3 N + ReO 4 − and (R 3 CH 3 N + Cl − )∙(NH 4 ReO 4 ) with a ratio of 1:3. A more detailed characterization of the microemulsion droplets was analyzed by mean of conductivity measurement, and the interactions in organic phase were deduced by Fourier transform infrared (FTIR) spectroscopy analysis. Further, the average dynamic radii of the nanodroplets in the organic phase were determined with the dynamic light scattering (DLS) method. Moreover, Re(VII) could be selectively extracted ( E % > 90%) when the ratio of Re(VII) to Mo(VI) was 2:5, 1:5, 1:10 and 1:20 (20 mg L − 1 of Re(VII)), respectively. Therefore, the extraction of Re(VII) from molybdenum solutions by microemulsion was an effective approach with high selectivity.

Amino-functionalized mesoporous materials based different mesoporous silica were prepared for the recovery of Mo(VI) from Re(VII)-containing solutions. The adsorption materials were characterized by SEM, HRTEM, TGA, XRD, N2 adsorption–desorption isotherms and Elemental analysis. The optimum type (SS5-1h-5.5@95) of mesoporous silica was determined by anchoring of mesoporous silica substrate with 3-aminopropyltriethoxysilane (APTES) via conventional methods and partitioned cooperative self-assembly process (PCSA process). Adsorption experimental data showed that the SS5-1h-5.5@95-APTES had a high affinity for Mo(VI) from Re(VII), and the maximum adsorption capacity was evaluated as 194.32 mg g− 1 in case of pH 1. Moreover, adsorption behavior, adsorption isotherm, adsorption kinetics and thermodynamics of Mo(VI) on the SS5-1h-5.5@95-APTES were studied, and adsorption mechanism was confirmed by FT-IR, Raman spectra and XPS analysis. The excellent affinity and selectivity make the SS5-1h-5.5@95-APTES become a potential material for recovery Mo(VI) from Re(VII) solution.

In this work, a facile and controllable multi-templating approach based on a solo nonionic surfactant P123 and peroxotitanic acid (PTA) was reported for the preparation of bimodal meso-mesoporous titania (BMM-TiO 2 ) with high surface area (150–243 m 2 g −1 ), high pore volume (0.3–0.6 cm 3 g −1 ), large mesopore sizes spanning from 8 to 16 nm (BJH pore size), and high & tunable crystallinity (Anatase or Anatase + Rutile). The BMM-TiO 2 was shown to be a homogeneous ‘mixture’ of two series of wormhole mesostructures with two modes of mesopore sizes that depend on both the contents of P123 and synthetic conditions. The formation of BMM structures was proposed to arise from both the formation of differentiated micellar structures of P123 (dual soft-templating) and their subsequent different mesostructural shrinkages driven by prolonged drying process ( i.e. , 100 °C for 12 h) in the presence of PTA. The low-temperature crystallization behaviours of PTA, unusual hard-templating effect of P123 and its carbon derivatives (3rd fold templating), large mesopores relative to the surrounding TiO 2 crystals are all believed to be responsible for the high thermal stability of the obtained BMM-TiO 2 . To our knowledge, it is for the first time reported that P123 plays such multiple templating roles (three folds in this work) in the preparation of meso-TiO 2 , not to mention that P123 was also confirmed to be a prerequisite for the formation bi-crystalline BMM-TiO 2 . In the photodegradation test of Rhodamine B in water by UV irradiation, other than the high surface area and synergistic effect between anatase and rutile phases, the BMM structures were also found to be advantageous to enhance the photocatalytic properties of mesoporous TiO 2 .

Four different silica mesostructures, SBA-15 with mesopore size (8.5 nm), SBA-15 with mesopore size (10.3 nm), mesocellular foam (MCF) with uniform cell size (33.2 nm), and MCF with bimodal mesoporosity, were grafted with aminopropyl groups and used for selective recovery of Mo(VI) from Re(VII)-containing effluent. Adsorption isotherms and mechanism of Mo(VI) adsorption on these materials were studied. The adsorbed complexes of Mo(VI) could be formed by ion exchange process or/and by chelation reaction. This study shows a new approach for fractional recovery and separation of Mo(VI) from Re(VII) by using amino-modified SBA-15-type mesoporous silica.

Aqueous solution was simulated by ammonium perrhenate and sodium sulfate in sulphuric acid system according to waste water from metallurgy process of copper and molybdenum. Molalities of perrhenate after extraction were measured at ionic strength from 0.2 to 2.0 mol kg−1 at temperature range 278.15 K to 303.15 K, using tri-n-octylamine as extractant. Optimization condition of extraction was determined in this sulphuric acid medium. The standard extraction constants K0 at various temperatures were obtained by method of polynomial approximation. Thermodynamic quantities for the extraction process were calculated.

In nickel electrolyte, Ag(I) was present at trace level concentration (10-20 mg L(-1)) and existed in the form of AgCli(1-i) coordination anion, instead of Ag(+) positive ion usually in several sources. In the present study, TSC-NH3-OCS adsorbent based on natural corn stalk modified by ammonia (NH3)-thiosemicarbazide (TSC) was synthesized and characterized using some instrumental techniques. The TSC-NH3-OCS adsorbent could selectively adsorb Ag(I) as AgCl(i)(1-i) coordination anion from the Ag(I)-Cu(II)-Ni(II) simulate nickel electrolyte, especially in the case of the very high levels of Cu(II) and Ni(II), which significantly outperforms the commercial available resins. The adsorption mechanism was believed to be electrostatic interaction of the protonated bands of AgCl4(3-) with protonated thiol form of the thioamide units by FTIR and XPS analysis. The maximum adsorption capacity in the Ag(I) single and Ag(I)-Cu(II)-Ni(II) ternary system were obtained and calculated as 153.54 and 46.69 mg g(-1), respectively. The reasons that the maximum adsorption capacity of AgCl(i)(1-i) from the single and ternary system varied widely could be explained by adsorption kinetic and thermodynamic results. In addition, three successive sorption/desorption cycle runs from ternary system were performed which indicated that the TSC-NH3-OCS adsorbent has a good performance for recovery Ag(I) from simulate nickel electrolyte.

Ga (III) imprinted bio-adsorbent (Ga(III)-AA-CS) based on acrylic-functionalized chitosan had been synthesized and applied for selective adsorption of Ga(III) from aqueous medium containing a certain competitive metal ions. The chemical structure, adsorption mechanism, thermal stability of Ga(III)-AA-CS were characterized by SEM, FTIR and elemental analysis. The influence of various infactors, such as the optimum adsorption conditions, selectivity and regeneration ability, was evaluated through a series of experiments. The corresponding results showed that the data fitted the pseudo-second-order model. At the same time, the equilibrium isotherms of the Ga(III)-AA-CS were well described by Langmuir model and the maximum adsorption capacity reached 192.40 mg g−1 at pH 3. The adsorption mechanism of Ga(III) was the cations exchange between Ga(OH)2+, Ga(OH)2+ and protonated amino hydrogen ions (R-NH3+) on the cavities of the Ga(III)-AA-CS. Moreover, the prepared Ga(III)-AA-CS exhibited outstanding affinity toward the targeted Ga(III) even in the presence of other similar competitive ions. In addition, Ga(III)-AA-CS can maintain about 90.25% efficiency after recycling six times.