Zeolite-like Structure Research Articles

One simple approach to novel germania and germanate aerogels

A synthetic approach to production of monolithic (NH4)3H(Ge7O16)(H2O)x and (NH4)2Ge7O15 aerogels is developed. Production of the aerogels with the germanate zeolite-like structure is reported for the first time. Thermal decomposition of (NH4)2Ge7O15 leads to formation of GeO2 aerogel, which has been obtained before using much more complex and expensive process of alkoxide hydrolysis. The suggested synthetic route might be used for production of novel luminescent, catalytic and anode materials. Luminescent properties of all obtained aerogels revealed excitation dependence. Based on excitation wavelengths it could exhibit blue, yellow-green and red luminescence. Luminescent properties for (NH4)3H(Ge7O16) (H2O)x and (NH4)2Ge7O15 are reported for the first time.

Bioremediation of trichloroethylene-contaminated groundwater using green carbon-releasing substrate with pH control capability

In this research, a sustainable substrate, termed green and long-lasting substrate (GLS), featuring a blend of emulsified substrate (ES) and modified rice husk ash (m-RHA) was devised. The primary objective was to facilitate the bioremediation of groundwater contaminated with trichloroethylene (TCE) using innovative GLS for slow carbon release and pH control. The GLS was concocted by homogenizing a mixture of soybean oil, surfactants (Simple Green™ and soya lecithin), and m-RHA, ensuring a gradual release of carbon sources. The hydrothermal synthesis was applied for the production of m-RHA production. The analyses demonstrate that m-RHA were uniform sphere-shape granules with diameters in micro-scale ranges. Results from the microcosm study show that approximately 83% of TCE could be removed (initial TCE concentration = 7.6 mg/L) with GLS supplement after 60 days of operation. Compared to other substrates without RHA addition, higher TCE removal efficiency was obtained, and higher Dehalococcoides sp. (DHC) population and hydA gene (hydrogen-producing gene) copy number were also detected in microcosms with GLS addition. Higher hydrogen concentrations enhanced the DHC growth, which corresponded to the increased DHC populations. The addition of the GLS could provide alkalinity at the initial stage to neutralize the acidified groundwater caused by the produced organic acids after substrate biodegradation, which was advantageous to DHC growth and TCE dechlorination. The addition of m-RHA reached an increased TCE removal efficiency, which was due to the fact that the m-RHA had the zeolite-like structure with a higher surface area and lower granular diameter, and thus, it resulted in a more effective initial adsorption effect. Therefore, a significant amount of TCE could be adsorbed onto the surface of m-RHA, which caused a rapid TCE removal through adsorption. The carbon substrates released from m-RHA could then enhance the subsequent dechlorination. The developed GLS is an environmentally-friendly and green substrate.

In situ construction of epoxy crosslinked Si-Al zeolite-like catalytic structure in wood to achieve high flame retardancy

As green renewable resources, wood and its composites are widely used in the construction field, which puts forward higher requirements for their flame-retardant performance. In this study, a high-temperature hydrothermal crystallization method for in situ constructing an epoxy crosslinked Si–Al zeolite-like structural wood composite (WZLC) was reported. Under the action of amine guiding agents and epoxy resin, the zeolite-like catalytic structure constructed in poplar wood comprised negative electrocatalytic sites, which can efficiently catalyze the formation of the carbon layer and endow WZLC with excellent flame retardant, smoke-suppression, and self-extinguishing properties. Compared with the untreated wood (WN), the thermal stability of the treated wood (WZLC) was greatly improved, and the amount of volatile organic compounds released during the decomposition process was significantly reduced. The heat release rate, total heat release, smoke production rate, and total smoke production of WZLC1 decreased by 50.23%, 44.14%, 45.21%, and 28.46%, respectively. Particularly, CO and CO2 yields of WZLC significantly decreased by 92.26% and 92.02%, respectively, indicating that the Si–Al zeolite-like catalytic structure displayed excellent catalytic flame retardant properties, which can effectively decrease the thermal decomposition rate and combustion risk of the WZLC. This method uses less flame retardants to achieve a good flame retardant and smoke suppression effect, thereby reducing the risk of environmental pollution caused by too many flame retardants.

Kinetics and thermodynamics study on low energy synthesis of porous geopolymer based solid amine sorbent for efficient CO2 capture

Geopolymers are new type of promising CO2 adsorption materials ascribing to their special zeolite-like structure, but the underdeveloped pore structure of geopolymer is still challenging when applied in CO2 capture. In this study, the pore content of geopolymer was significantly improved by nearly 71 time via a facile acid treatment strategy, and this process overcame only low energy barriers of 1.852, 4.336 kJ/mol for denatrium and dealumination. Moreover. after the amine impregnation, the resultant adsorbent exhibited high CO2 adsorption capacity up to 4.18 mmol/g at 50 °C in 15vol%CO2/85vol%N2, and the capacity remained above 95% after 5 cycles, which are significantly superior than the reported geopolymer-based CO2 adsorbents. Kinetics, thermodynamics and in-situ DRIFTs analysis confirm that the adsorption of CO2 is mainly oriented by the zwitterion reaction mechanism by forming carbamate, while the acid treatment of geopolymer greatly improved the dispersity of the amine molecules that enhanced the mass transfer of CO2 to the active adsorption site. Moreover, the silanol nest in the geopolymer matrix formed during the acid treatment process directly participated in the CO2 adsorption process, which decreased the energy barrier for the proton transfer between CO2 and amine groups, thereby exhibiting excellent CO2 capture performance.

Development of sulfhydryl grafted hierarchical porous geopolymer for highly effective removal of Pb (II) from water

Geopolymers have captured increasing attention in the adsorption of lead ions due to their zeolite-like three-dimensional network structure, and several advantages such as low cost and environmental friendliness. However, their adsorption performance is limited by a small specific surface area and fewer adsorption sites. In this study, a metakaolin-based geopolymer was first pretreated with different concentrations of nitric acid to increase the porosity and surface area. Subsequently, the sulfhydryl functional group was grafted onto the above hierarchical porous geopolymer, which is a inorganic material with multistage pore structure. The result of N2 adsorption and desorption results demonstrated that an increase in specific surface area and number of grafting sites for sulfhydryl groups with increasing acid concentration when the highest nitric acid concentration used is 5 mol/L and acid treatment time is for 5 h. The specific surface area of the fabricated geopolymers was as high as 343.87 m2/g and the concentration of silanol groups reached 4.46 mmol/g at 3 mol/L acid concentration. The maximum Pb2+ adsorption quantities for SH-1HGeo, SH-2HGeo, and SH-3HGeo samples were 173.2 mg/g, 239.8 mg/g, and 386.3 mg/g, respectively. The adsorption processes were in accordance with the pseudo-second-order kinetic model and the Langmuir models, indicating that the Pb2+ adsorption on the sulfhydryl grafted hierarchical porous geopolymer was mainly chemisorption and monolayer adsorption. The contribution of different Pb2+ adsorption mechanism on geopolymer was ion-exchange, while that on SH-3HGeo was functional group complexation.

Hydrothermal syntheses of d10-based Zn(II) and Cd(II) metal–organic frameworks for the catalysis of the Knoevenagel condensation

Metal–organic frameworks (MOFs) are compounds that feature metal clusters coordinated with organic ligands, forming impressive structures and properties. In this study, two MOFs of Zn(II) and Cd(II) were synthesized using the organic compound 5‑hydroxy-2-pyrazinecarboxylic acid, forming Zn-MOF and Cd-MOF. To better understand the intricate structures of these MOFs, single-crystal X-ray crystallography was used to characterize their respective structures. The results showed that both MOFs have complex three-dimensional supramolecular structures that are highly symmetric and contain water molecules. Additionally, topological analysis of the MOFs indicated that they have a zeolite-like structure. The Hirshfeld surfaces analysis revealed that both crystal structures could preferentially interact with other molecules through hydrogen bonds. The MOFs were found to have a direct band gap, with the energy observed to be 2.44 and 2.71 eV for the Zn-MOF and Cd-MOF systems, respectively. The hydrogen bond formation ability of the MOFs, in combination with their low band gap energy, make them highly suitable for use in the Knoevenagel condensation reaction in water. Overall, the results of this study provide important insights into the unique properties and potential applications of MOFs in diverse fields.

Magnetocaloric and hydrogen storage multi-functional properties of Eu4Ga8Ge16 compounds

We investigated the anisotropic magnetic, electrical transport, and heat capacity of Eu4Ga8Ge16 single crystals. Magnetization measurements with temperature and magnetic field revealed a complex behavior. Specifically, we observed anisotropic metamagnetic transitions at low magnetic field, and inverse hysteresis at high magnetic fields. These phenomena can be attributed to a Heisenberg ferromagnetic spin chain aligned along the a-axis. Additionally, this ferromagnetic behavior is interspersed with antiferromagnetic interactions between adjacent Heisenberg spin chains. We also noticed an anomalous increase in electrical resistivity at low temperature under magnetic fields, as well as different temperature-exponents of ρ(T) depending on crystal directions, which are attributed to the anisotropic scattering of carriers due to anisotropic magnetic interactions. We also evaluated the magnetocaloric effect and found a substantial magnetic entropy change than those of type-I Eu-based clathrates. The high entropy change (-ΔSM = 13.5 J kg−1 K−1) and adiabatic temperature difference (ΔTad = 7.8 K) near Néel temperature TN = 7.9 K reveal that the Heisenberg spin chain system might be advantageous for inducing a larger magnetic entropy change. Furthermore, we measured the hydrogen storage capacity of Eu4Ga8Ge16 as a multifunctional property because the zeolite-like cage structure can be a good candidate for hydrogen storage applications. Although the hydrogen storage capacity is considerably lower than that of the leading-edge materials, the hydrogen storage capacity can be improved further when we control the Eu-deficiency to place the hydrogen molecule at the cage site, because the hydrogen molecules reside at the (Ga,Ge) framework not in the cage site for fully occupied Eu atomic chain compounds. Hence, Eu4Ga8Ge16 emerges as a versatile substrate for engineering multifunctional energy materials, excelling in both low-temperature magnetocaloric effects and hydrogen storage potential.

Optimized preparation of gangue waste-based geopolymer adsorbent based on improved response surface methodology for Cd(II) removal from wastewater

Resource utilization of gangue solid waste has become an essential research direction for green development. This study prepared a novel gangue based geopolymer adsorbent (GPA) for the removal of Cd(II) from wastewater using pretreatment gangue (PG) as the main raw material. The ANOVA indicated that the obtained quadratic model of fitness function (R2 > 0.99, P-value <0.0001) was significant and adequate, and the contribution of the three preparation conditions to the removal of Cd(II) was: calcination temperature > Na2CO3:PG ratio > water-glass solid content. The hybrid response surface method and gray wolf optimization (RSM-GWO) algorithm were adopted to acquire the optimum conditions: Na2CO3:PG ratio = 1.05, calcination temperature of 701 °C, solid content of water glass of 22.42%, and the removal efficiency of Cd(II) by GPA obtained under the optimized conditions (GPAC) was 97.84%. Adsorption kinetics, adsorption isotherms and characterization by XRD, FTIR, Zeta potential, FSEM-EDS and BET were utilized to investigate the adsorption mechanism of GPAC on Cd(II). The results showed that the adsorption of Cd(II) from GPAC was consistent with the pseudo-second-order model (R2 = 0.9936) and the Langmuir model (R2 = 0.9988), the adsorption was a monolayer adsorption process and the computed maximum Cd(II) adsorption (50.76 mg g−1) was approximate to experimental results (51.47 mg g−1). Moreover, the surface morphology of GPAC was rough and porous with a specific surface area (SSA) of 18.54 m2 g−1, which provided abundant active sites, and the internal kaolinite was destroyed to produce a zeolite-like structure where surface complexation and ion exchange with Cd(II) through hydroxyl (-OH) and oxygen-containing groups (-SiOH and -AlOH) were the main adsorption mechanisms. Thus, GPAC is a lucrative adsorbent material for effective Cd(II) wastewater treatment, complying with the “high value-added” usage of solid wastes and “waste to cure poison” green sustainable development direction.

Computational simulation-driven discovery of novel zeolite-like carbon materials as seawater desalination membranes.

Freshwater is a scarce and vulnerable resource that has never encountered such an extensive focus on a nearly worldwide scale as it does today. Recently, it has been found that desalination powered by two-dimensional (2D) carbon materials as separation membranes has significantly reduced the operational costs and complexity but presents heavy requirements for the structural stability and separation properties of the membrane materials. Here, we combined carbon materials with promising adsorption properties and zeolites characterized by a regular pore structure to obtain a zeolite-like structured carbon membrane Zeo-C and investigated the suitability of the Zeo-C membrane for seawater desalination based on the computational-simulation-driven approach. The results of molecular dynamics (MD) simulations and density functional theory (DFT) calculations revealed that the periodic pore distribution conferred favorable structural stability and mechanical strength to the Zeo-C desalination membrane. The rejection rate of Na+ and Cl- is ensured at 100% under a pressure of 40-70 MPa, and that of Na+ could reach 97.85% even though the pressure increases to 80 MPa, exhibiting superior desalination properties. The porous nature of the zeolite-like structure and the low free energy potential barrier are conducive for reliable adsorption and homogeneous diffusion of salt ions, which facilitates the acquisition of desirable water molecule permeability and salt ion selectivity. In particular, the interlinked delocalized π-network imparts inherent metallicity to Zeo-C for self-cleaning in response to electrical stimulation, thereby extending the lifetime of the desalination membrane. These studies have greatly encouraged theoretical innovations and serve as a guiding reference for desalination materials.

Study on using rice-husk ash as an adsorbent for some antibiotic and anti-inflammatory drugs in aqueous

Rice-husk ash (RHA) is prepared from a by-product of rice production. Its main component is silic dioxide. Thanks a zeolite-like structure, it could be used as an adsorbent. In this study, RHA was used to remove some antibiotic and anti-inflammatory drugs in aqueous medium such as Cefuroxim, Dexamethasone, Methylprednisolone, Prednisolon. These drugs are recommended to use at home for Covid-19 patients. The RHA has a specific surface area of 179.797 m2/g), the pore size of 63.547 m2/g, the average particle size of 3.8 mm. The zeta potential of RHA in distilled water of -42.5 V, the point of zero charge of 6.7. The main composition of elements in RHA is Si, O, C. Among investigated samples, the Cefuroxim adsorption efficiency of RHA is the best, with a adsorption capacity reached 1.43 mg.g-1 and adsorption efficiency reached 86.00 % at the optimum adsorption condition of pH solution of 7, adsorption time of 150 min, RHA weight of 0.3 g and the initial drug concentration of 5.0 mg.L-1.

Who Is Who in the Eudialyte Group: A New Algorithm for the Express Allocation of a Mineral Name Based on the Chemical Composition

Eudialyte-group minerals (EGMs) are Na-Ca zirconosilicates typical for peralkaline plutonic rocks. In the zeolite-like crystal structure of these minerals, there are many sites of different volumes and configurations, and therefore EGMs can include up to one-third of the periodic table. Although there are preferred sites for many elements in the crystal structure of eudialyte-group minerals, the same element can appear in several sites. In addition, many sites may be partially or fully vacant. Currently, 30 mineral species are established in the eudialyte group. However, this diversity is, in fact, limited to holotype specimens. To name any mineral from the eudialyte group, you need to solve its crystal structure and compare it with holotypes. Meanwhile, the composition (and, therefore, the name) of any mineral of the eudialyte group is an excellent indicator of the composition of the mineral-forming media, which is very important to petrological and mineralogical studies. In this article, we propose a diagnostic scheme for minerals of the eudialyte group, based only on the chemical composition. The scheme includes five consecutive steps, each of which evaluates the content of a species-forming element (or the sum of such elements). This scheme can be supplemented by new members without changing its hierarchical structure.

Formation of hot ice caused by carbon nanobrushes. II. Dependency on the radius of nanotubes

Stable crystalline structures of confined water can be different from bulk ice. In Paper I [T. Yagasaki et al., J. Chem. Phys. 151, 064702 (2019)] of this study, it was shown, using molecular dynamics (MD) simulations, that a zeolite-like ice structure forms in nanobrushes consisting of (6,6) carbon nanotubes (CNTs) when the CNTs are located in a triangle arrangement. The melting temperature of the zeolite-like ice structure is much higher than the melting temperature of ice Ih when the distance between the surfaces of CNTs is ∼0.94 nm, which is the best spacing for the bilayer structure of water. In this paper, we perform MD simulations of nanobrushes of CNTs that are different from (6,6) CNTs in radius. Several new porous ice structures form spontaneously in the MD simulations. A stable porous ice forms when the radius of its cavities matches the radius of the CNTs well. All cylindrical porous ice structures found in this study can be decomposed into a small number of structural blocks. We provide a new protocol to classify cylindrical porous ice crystals on the basis of this decomposition.

Novel activated carbon route to low-cost geopolymer based porous composite with high mechanical resistance and enhanced CO2 capacity

Geopolymers are regarded as zeolite-like structure materials but do not exhibit satisfactory zeolite-like capabilities because of their limited porosity and surface area. Geopolymer-zeolite composites have been prepared by embedding zeolite powders into the geopolymer matrix or through the in-situ hydrothermal route, however, it is challenging to obtain both the sufficient mechanical resistance as well as porosity. In this study, a novel activated carbon route was proposed for the first time to overcome the above drawbacks via a facile two-step reaction of activated carbon embedded polycondensation and hydrothermal crystallization. The initiative incorporation of activated carbon into the geopolymer generated an interface in the matrix and improved the porosity of the composite simultaneously, the mechanical resistance loss caused by the interface was effectively mitigated by increasing the alkalinity of the activator. The hydrothermal product exhibited an enhanced specific surface area of 256 m2/g due to the improvement of zeolite yields with the aid of the deliberate interface. The hydrothermal zeolite formation process didn't affect the mechanical resistance because the zeolite in the matrix was combined with the geopolymer through [SiO4]4- and [AlO4]5- tetrahedral by sharing the bridging oxygens. This finally resulted in an excellent compressive strength of 23.1 MPa and enhanced CO2 capacity of 60.14 cc/g at 1 atm and 35 °C, both of which are higher than those of geopolymer-based adsorbents reported for CO2 capture to date.

Zeolite based Geopolymer from Biomass: a Sustainable Adsorbent for Water Softener

Water quality in several areas in Semarang, especially in Tugu sub-district, is still very low and unsuitable for drinking. Ground water contaminated with Ca2+ and Mg2+ ions which is commonly known as hard water. This study aims to examine the potential of zeolite-based geopolymer adsorbents, materials which have a zeolite-like structure but are basically geopolymers. Synthesis of zeolite based geopolymers from rice husk ash, kaolin and NaOH activators has been successfully carried out by the sol gel method. Three-dimensional networks have been formed from Silica (SiO2) and Alumina (Al2O3). Activator solution, NaOH, with variations in concentrations of 4 M (Geopolymer 4), 8 M (Geopolymer 8) and 12M (Geopolymer 12) gives significant differences. As the higher the concentration of activator solution, the more silica and alumina dissolved so that the geopolymer becomes amorphous. These results are consistent with XRD and FTIR data. Geopolymer 12 has an adsorption capacity of 97.4% is the best adsorbent in adsorbing Ca2+ and Mg2+ metal ions with operating conditions at 40°C for 60 minutes. This shows that there is a close relationship between synthesis methods, structural characterization and geopolymer adsorption activities. The higher concentration of NaOH gives amorphous geopolymers. NaOH will activate the silica and alumina surfaces on the geopolymer, making it easier for adsorbents to absorb and interact with the adsorbate molecules, namely Ca2+ ions and Mg2+ ions.

Self-solidification/stabilisation of electrolytic manganese residue: Mechanistic insights

Electrolytic manganese residue (EMR) is a type of industrial solid waste with high content of sulphur and heavy metals (HMs). In this study, a novel cementitious material composite is synthesised from ground granulated blast furnace slag, clinker, lime and EMR. It is used to solidify and stabilise EMR. The solidified products are characterised by mechanical properties and environmental effect. The solidification/stabilisation mechanism is revealed by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy with energy dispersive X-ray analyser. The experiment results show that the UCS of solidified bodies increases with the curing age and dosage of cementitious materials. HMs in solidified samples meet the standard threshold. HMs switch to a stable form during curing, that is, S/S has a significant inactivation effect on HMs and can protect HMs from leaching in long-term. The contents of gypsum, charmarite and calcium manganese silicate gradually appear with curing time. Charmarite and gypsum can contribute the increasing trend of compressive strength with curing time. The formation of calcium manganese silicate shows that the presence of HMs in EMR can be involved in the hydration reaction. The binding energy of Si 2p decreases over curing time due to the enlarged degree of polymerisation of Si. The Si–O energy of S/S samples verifies the formation of zeolite-like structure, which can provide sufficient adsorption capacity to HMs and mechanical strength. The microstructure of S/S samples becomes dense with curing time. Gypsum is conducive to the rapid stabilisation of HMs (except Mn). Meanwhile, CSH gel can effectively immobilise all HMs by HM–gel reaction. Incorporating EMR into cementitious materials to solidify/stabilise itself is one way of utilising solid wastes as construction materials for civil engineering applications.

Two amino acid-templated metal phosphates: surfactant-thermal synthesis, water stability, and proton conduction.

Two new metal phosphates, namely, Zn(HPO4)(C6H11NO2) (1) and (C5H10NO2)Ga4(PO4)4F·3H2O (2), were prepared under surfactant-thermal conditions. Single-crystal X-ray diffraction analyses reveal that compound 1 has a zigzag-chain structure decorated with homoproline and compound 2 has a three-dimensional zeolite-like structure templated by proline. Notably, compound 2 remains stable in both boiling water and aqueous solutions with a pH range of 2-12. It shows a proton conductivity of 8.89 × 10-4 S cm-1 at 85 °C and 95% relative humidity.

Surface Modification of Fly Ash by Poly(1,5-Diaminonaphthalene) for Removal of Hexavalent Chromium from Water

The Fly Ash (FA) was treated by NaOH solution in order to transform into the zeolite-like structure. Poly(1,5- diaminonaphthalene) [p(1,5-DAN)] was synthesized via in-situ chemical oxidation on the surface of NaOH-Treated Fly Ash (TFA) to form p(1,5-DAN)/TFA composite. The p(1,5-DAN)/TFA composite was used as a novel sorbent for removal of Cr(VI) ions from aqueous solutions. The maximum adsorption capacity (at pH 2, 298 K) calculated according to Langmuir isotherm model was 4.4 mg/g. This result suggested that p(1,5-DAN)/TFA was a promising adsorbent for Cr(VI) ions in the environmental treatment.

Interplay of alternation and further neighbor interaction in S=12 spin chains: A case study of Cs2CuAl4O8

Using Wannier function formulation and total energy calculations by first-principles density functional theory (DFT), we derive the underlying spin model of a recently synthesized compound, ${\mathrm{Cs}}_{2}{\mathrm{CuAl}}_{4}{\mathrm{O}}_{8}$, having zeolitelike network structure. The computed magnetic interactions show that the interchain Cu-Cu interactions are negligibly small compared to intrachain Cu-Cu interactions, thus characterizing ${\mathrm{Cs}}_{2}{\mathrm{CuAl}}_{4}{\mathrm{O}}_{8}$ as a prototypical one-dimensional (1D) spin-$\frac{1}{2}$ system. Interestingly, the DFT-derived 1D spin model features a combination of alternating ferromagnetic-antiferromagnetic interactions, together with the presence of both nearest- and next-nearest-neighbor interactions, making it an unprecedented case. The solution of the derived spin model of the compound using the quantum Monte Carlo technique shows reasonably good agreement with the experimental susceptibility data, measured in the presence of the magnetic field. The presence of spin gap is suggested by quantum Monte Carlo simulations in the zero-field condition, which is cross-checked by a more rigorous exact diagonalization study. Motivated by the intricacy of the derived spin model, we further examine the ground-state properties of this model in the parameter space of exchange interactions, which shows the possibility of driving quantum phase transition between gapped and gapless spin excitation. Our study is expected to shed light on the fascinating world of 1D quantum spin systems.

Solidification/stabilization mechanism of Pb(II), Cd(II), Mn(II) and Cr(III) in fly ash based geopolymers

Geopolymers are new cementitious materials, which can effectively solidify/stabilize heavy metal ions. Fly ash is an industrial waste from the coal-consumed power plant. With thermal power projects continuously building in the world and the emissions and accumulation quantities of fly ash are increasing yearly. At the same time, with the development of modern industry, waste and waste water containing heavy metals are continuously discharged, so that heavy metal pollution has been the very serious world environmental problems. Aiming at the problem of fly ash and heavy metal pollution, this study referred to solidification/stabilization (S/S) of Pb (II), Cd (II), Mn (II) and Cr (III) in fly ash based geopolymers prepared using composite activator of sodium silicate and sodium hydroxide. The solidification (S/S) results had been explained by means of the leaching and compressive strength of the solidification (S/S) geopolymers (solidified bodies) acquired. The analysis was performed through chemical analysis, X-ray Diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), Scanning Electron Microscope (SEM), Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and compressive strength tests. The results indicated that heavy metal ions could be effectively solidified in fly ash based geopolymers with a replacement of safe metal ions like Na (I) and Ca (II). Heavy metal ions had different effects on the compressive strength of geopolymers. (1.5 wt%) Pb (II) was beneficial to improve the compressive strength of geopolymers, and reached 49.34 MPa at 28 d. The XRD patterns indicated an amorphous structure and zeolite-like structure of aluminosilicate. The FTIR patterns study suggested changes of the Si-O-T (T = Si or Al) peak in the geopolymers. The SEM analysis revealed almost condensed homogenous surface of geopolymers. ICP-AES results showed that the geopolymer showed a high degree of solidification (S/S) of the heavy metal ions; in all samples, the solidification rates reached 99.9%. The mechanism of heavy metal ions being solidified was the interaction of physical fixation, adsorption and ion exchange. Finally, the pilot-scale test can achieve the same result on the basis of this study and made preparations for the future of industrialization.

Metal organic frameworks-derived porous carbons/ruthenium oxide composite and its application in supercapacitor

In this study, we employed traditional method to synthesize zeolitic imidazolate framework-8 crystals (ZIF-8), one of the well-known metal organic frameworks (MOFs) with zeolite-like pore structure. Then, ZIF-8 crystal was served as a sacrificial template and carbon resource to prepare nanoporous carbons material (PCs) with high specific surface area (1230 m2 g−1) and abundant pore structure (average pore diameter is 2.8 nm). Finally, we used conventional reflux and subsequent thermal treatment to achieve composites, in which the PCs exploited as a substrate to grow ruthenium oxide (RuO2) nanoparticles on its surface. The resulting RuO2/PCs composite with 70.7 wt % RuO2 loading revealed excellent electrochemical performances in terms of high specific capacitance (539.6 F g−1 at 1 A g−1) and good rate capability (capacitance retain 81.5% at 200 A g−1 as compared to that of 1 A g−1) in three electrode system. Furthermore, the symmetric supercapacitor based on RuO2/PCs electrodes delivered a high energy density of 23.38 Wh kg−1 at a power density of 600 W kg−1, indicating a potential application prospect.