Zeolite Na-P1 Research Articles

Effective removal of organic dyes using the ultrasonic-assisted hydrothermal synthesis of NaP zeolite doping Cu or Fe in Fenton-like oxidation systems

NaP zeolite was successfully synthesized via ultrasonic-assisted hydrothermal synthesis. The approaches for Cu or Fe doping were screened. Additionally, the oxidation process of methylene blue (MB) and methyl violet-6B (MV-6B) by the doped NaPultra zeolites was surveyed. NaPultra zeolite exhibited higher crystallinity (94.99%), while the crystallization temperature and duration decreased from 120 °C to 90 °C and from 8 h to 4 h with the n(SiO2)/n(Al2O3) increasing from 2.0 to 4.0, compared to the hydrothermal synthesis. At the ultrasonic power intensity of 30% and the density of 60 mL/W, the conversion rates of Si and Al rosed from 66.46% to 84.68% and from 73.75% to 95.25%, respectively. Comparatively, the complexation approach demonstrated superior findings in the crystallinity (Fe-NaPultra: 92.37% and Cu-NaPultra: 94.14%) at the n(Fe(NO3)3):n(Al2O3) ratio of 1:4 and the n(Cu(NO3)2):n(Al2O3) ratio of 1:6. The ultrasonic resulted in the smaller crystal sizes for Fe-NaPultra (1.90 μm) and Cu-NaPultra (1.80 μm). Cu-NaPultra displayed better oxidation performance in the elimination of MB (93.22%) and MV-6B (98.71%) via the HO at the condition of pH = 5.0, 30 min, 2.5 g/L, 50 mg/L, and 25 °C. Through the combined action of adsorption and Fenton-like oxidation, the rapid enrichment of organic dyes by the zeolite was realized, and the dyes were removed efficiently. Cu-NaPultra was capable of retaining good removal performance throughout four cycles, suggesting that it is a promising catalyst for Fenton-like oxidation reactions and may help to pave the way for the removal of organic dyes.

Hydrothermal synthesis of zeolitic material from circulating fluidized bed combustion fly ash for the highly efficient removal of lead from aqueous solution

The utilization of coal fly ash derived from circulating fluidized bed combustion (CFBFA) still faces great challenges because of its unique characteristics. In this study, a zeolitic material with Na-P1 zeolite as the main phase was successfully synthesized via a hydrothermal method by using CFBFA as the raw material. The effects of hydrothermal temperature, time, and added CTAB amount on the characterizations of synthesized materials were investigated by XRD, SEM, and XPS. The properties of the optimal zeolitic material and its adsorption performance for Pb2+ in aqueous solution were evaluated. The influences of pH, initial concentration, dosage, and temperature on Pb2+ adsorption were also examined. Results revealed the following optimal parameters for the synthesis of zeolitic material: NaOH concentration of 2 mol·L−1, solid-to-liquid ratio of 1:10 g·ml−1, hydrothermal temperature of 110 °C, hydrothermal time of 9 h, and CTAB amount of 1 g (per 100 ml solution). The adsorption capacities of the zeolitic material reached 329.67, 424.69, and 542.22 mg·g−1 when the pH values of aqueous solution were 5, 6, and 7, respectively. The Pb2+removal efficiency can reach more than 99% in aqueous solution with the initial concentrations of 100–300 mg·L−1 under pH 6 and suitable adsorbent dosage. The adsorption and kinetics of Pb2+ on the zeolitic material can be described by Langmuir isotherm and pseudo-second-order kinetic models, respectively. The ion exchange between Pb2+ and Na+ and chemisorption are the main adsorption mechanism. All these findings imply that the synthesis of low-cost adsorbent for Pb2+ removal from weak acid and neutral aqueous solution provides a highly effective method to utilize CFBFA.

Synthesis of Zeolites from Fine-Grained Perlite and Their Application as Sorbents.

The hydrothermal alteration of perlite into zeolites was studied using a two-step approach. Firstly, perlite powder was transformed into Na-P1 (GIS) or hydro(xy)sodalite (SOD) zeolites at 100 °C and 24 h using 2 or 5 M NaOH solutions. Secondly, the Si:Al molar ratio of the reacted Si-rich solution was adjusted to 1 by Na-aluminate addition to produce zeolite A (LTA) at 65 or 95 °C and 6 or 24 h at an efficiency of 90 ± 9% for Al and 93 ± 6% for Si conversion. The performance of these zeolites for metal ion removal and water softening applications was assessed by sorption experiments using an artificial waste solution containing 4 mmol/L of metal ions (Me2+: Ca2+, Mg2+, Ba2+ and Zn2+) and local tap water (2.1 mmol/L Ca2+ and 0.6 mmol/L Mg2+) at 25 °C. The removal capacity of the LTA-zeolite ranged from 2.69 to 2.86 mmol/g for Me2+ (=240–275 mg/g), which is similar to commercial zeolite A (2.73 mmol/g) and GIS-zeolite (2.69 mmol/g), and significantly higher compared to the perlite powder (0.56 mmol/g) and SOD-zeolite (0.88 mmol/g). The best-performing LTA-zeolite removed 99.8% Ca2+ and 93.4% Mg2+ from tap water. Our results demonstrate the applicability of the LTA-zeolites from perlite for water treatment and softening applications.

Alkali treatment to transform natural clinoptilolite into zeolite Na–P: Influence of NaOH concentration

In this study, natural clinoptilolite was treated with NaOH solutions of different concentrations under mild ambient conditions. The composition and structure of the as-prepared samples were characterized, and their performance was assessed in terms of the removal of the heavy metal ions Cd2+, Cu2+, and Cr3+ from the aqueous solution. The results showed that the composition, structure, and capability of removal of heavy metal ions of the samples were significantly influenced by the NaOH concentrations. The crystal structure of clinoptilolite remained invariant under a relatively low NaOH concentration (≤0.5 M), began transforming into zeolite Na–P under a medium NaOH concentration (∼1.0 M), and then completely transformed into it under a high NaOH concentration (2.0–4.0 M). The samples treated with NaOH had lower SiO2/Al2O3 ratios, and were superior to unmodified natural zeolite in removing the heavy metal ions. This method of treatment with relatively high concentrations of NaOH is a simple and effective way to transform natural clinoptilolite into the zeolite Na-P rich ion exchanger, which is suitable for removing heavy metal ions.

Sustainable Management of Salt Slag

The management of salt slag, a waste from the secondary aluminum industry, is associated with huge environmental concerns due to the risk of atmospheric pollution (emission of toxic gases), groundwater contamination (high salt content that can percolate and cause an increase in salinity) and soil unavailability (large extensions required for disposal). Therefore, the development of a sustainable process for its treatment and recovery is of the utmost importance. In this work, a two-step process for the valorization of salt slag was developed that rendered zeolite as the main added-value product and NaCl and NH3 as byproducts. First, salt slag was hydrolyzed at 90 °C and at a solid/water ratio of 1/3. More than 90% of salt and ~90% of ammonia were recovered. In a second step, the hydrolyzed slag was completely transformed into a NaP zeolite under mild hydrothermal conditions. The zeolite exhibited specific surface area (17 m2 g−1), cation exchange capacity (2.12 meq g−1) and zeta potential (−52 mV) values that represent good characteristics for use in the removal of metal ions from aqueous effluents. The transformation of salt slag into zeolite can be considered a sustainable process with a high contribution to the circular economy.

Strategic Synthesis to Disperse Zeolite NaY in Lead Tree Wood

The goal of this work is to synthesize zeolite NaY inside Lead tree wood. The wood is mixed with zeolite seed gel before mixing with feed gel and subsequent hydrothermal treatment. In the first trial, the dried and untreated Lead tree wood is mixed with the gel of zeolite NaY before the hydrothermal process. Only zeolite NaP is produced. Then, sonication is applied to the wood and zeolite gel mixture before the hydrothermal process. The product is mixed with the phase of NaP and NaY. In the next attempt, the wood is treated with acid reflux before mixing with the zeolite seed gel. NaY is successfully produced inside the wood. When sonication is also applied, the amount of NaY is increased. The presence of zeolites in the wood are confirmed by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and thermogravimetric analysis. Moreover, the composites are tested for the adsorption of nickel (II) ions from aqueous solutions. The novel Lead tree wood-zeolite NaY composite has the potential as an adsorbent which could be separated easily from the liquid media.

Micro-meso structure NaP zeolite @TiO2 nanocomposite: eco-friendly photocatalyst for simultaneous removal COD and degradation of methylene blue under solar irradiation.

A low-cost NaP zeolite@TiO2 nanocomposite catalyst with zeolite Si/Al ratio lower than three were synthesized for the first time under hydrothermal condition. The nanocomposites were characterized by different methods such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), N2 physisorption, NH3 temperature-programmed desorption (NH3-TPD), fluorescence microscopy, thermal analysis (TGA/DTA) and zeta potential analysis. The results showed that a micro-meso structure NaP zeolite with higher surface area and acidity with respect to pure zeolite was prepared. TiO2 nanoparticle was dispersed over the whole of zeolite without aggregation. A reduction of the TiO2 bandgap nanoparticle was observed from DRS spectra. The photocatalytic activity of low-cost NaP zeolite@TiO2 nanocomposite was tested for simultaneous methylene blue dye (MB) and chemical oxygen demand (COD) under solar and ultraviolet light. The result showed that the nanocomposite catalyst has great potential (above 90%) for COD removal discolouring of MB (about 99.6%) at room temperature. The optimum amount of some parameters such as the loaded amount of TiO2 (0.36g), catalyst dosage (0.1g), time (2h), initial dye concentration (100mg/L), solution pH value (about 7) under solar light were considered. In addition, present negative charge in the surface that show in zeta potential confirm the high activity of catalyst to interaction with cationic dye. As a further advantage, the NaP zeolite@TiO2 nanocomposite was easier to be separated in aqueous media than the pure TiO2 powders, making possible the reuse several times (over five runs) without using oxidant. Finally, the NaP zeolite@TiO2 nanocomposite was used for COD abatement in wastewater from two real industrial streams. The MB degradation kinetics were fitted by a pseudo-first-order model with K = 0.534h-1.

Fly-ash derived Na-P1, natural zeolite tuffs and diatomite in motor oil retention

Aluminosilicate materials of various grain sizes, i.e., Kimolos, Samos and Sorano zeolite tuffs, Samos diatomite and synthetic zeolite prepared from Meliti fly ash via alkaline hydrothermal treatment, were tested as new sorbents for oil leakage remediation. Two lubricant oils of different viscosity, i.e., SHELL HELIX HX5 20 W-50 and ULVAC SMR-100 were selected as potential adsorbates. All sorbents employed demonstrated exceptional oil retention capacity values exceeding 100% (w/w); specifically, Kimolos and Sorano zeolites as well as thermally treated Samos diatomite proved best reaching 160% (w/w) oil sorption. Mordenite and phillipsite were mostly detected in Kimolos and Italian zeolite tuffs, respectively. Na-P1 zeolite, produced for the first time from Meliti fly ash without pretreatment via a low-temperature hydrothermal procedure, was characterized by XRD and SEM. The zeolitization process, leading to Na-P1 as the sole synthesis product, was carried out without the use of additives. The synthetic Na-P1 zeolite displayed significant sorption capacity, retaining 125 and 105% (w/w) of the viscous and less viscous oils tested, respectively. Thus, valorization of all aluminosilicate materials employed was achieved. Both porosity measurements and SEM micrographs demonstrated that the highest lubricant oil retention values were reached by macroporous adsorbents having open structure and large surface area, suitable for overcoming the fluid’s resistance to flow and avoiding pore-blocking effects.

Heavy Metal Removal from Aqueous Solutions Using Fly-Ash Derived Zeolite NaP1

Fly-ash derived zeolites have recently -received great attention as cheaper adsorbents to remove heavy metals from water since they can be synthesized from a waste product. In this study, we evaluated the single- and multi-cation adsorption efficiencies of fly-ash derived NaP1 for the removal of zinc (Zn), copper (Cu) and lead (Pb). We also determined precipitation and leaching from NaP1 during the adsorption. Results showed that the uptake capacities for Zn (34 mg/g) and Pb (192 mg/g) were higher than other fly-ash derived NaP1 and adsorbents such as clinoptilolite and activated carbon. The Cu uptake was estimated ~ 14.6 mg/g. Pb2+ > Cu2+ > Zn2+ is the order for the metal cation selectivity of NaP1. Langmuir adsorption isotherm and pseudo-second order kinetic model fitted best for all elements. The metal uptake occurred in 15 min. Diffusion of hydrated metals through microporous channels is the rate-determining step.

Direct single-step synthesis of phase pure zeolite Na–P1, hydroxy sodalite and analcime from coal fly ash and assessment of their Cs+ and Sr2+ removal efficiencies

Combustion by-products of coal from thermal power plants cause environmental pollution; efforts are made to develop techniques and green processes that could reduce the waste volume and convert the waste to useful materials. Synthesis of phase pure zeolites from coal fly ash and its use as adsorbent and ion exchangers to remove Cs+ and Sr2+ from simulated nuclear waste solutions is the focus of the current study. Zeolite Na–P1, hydroxy sodalite and analcime were synthesized from fly ash obtained from an Indian thermal power plant by using hydrothermal method. Zeolite synthesis conditions were optimized by studying the effect of concentration of NaOH solution, homogenization time, hydrothermal temperature and time. The zeolite phase formation, surface morphology, thermal stability studies were carried out by XRD, SEM, TG-DTA techniques; specific surface area was determined by BET analysis. Crystalline pristine zeolite Na–P1 was prepared from fly ash on reaction with 1 M NaOH at 150 °C. Similarly, hydroxy sodalite and analcime were also synthesized from the fly ash by hydrothermal reaction with 3 M NaOH at 150 °C and 5 M NaOH at 200 °C respectively. The removal efficiencies of synthesized zeolites were investigated with aqueous simulated nuclear waste solutions containing Cs+ and Sr2+. The adsorption capacities and cation exchange capacity (CEC) of zeolite Na–P1, hydroxy sodalite and analcime for Cs+ and Sr2+ ions were demonstrated. The results show the adsorption capacity of Na–P1 for Cs+ is 39.3 mg/g and for Sr2+ is 92.48 mg/g respectively and is a better adsorbent than analcime and hydroxy sodalite.

Effects of aging time on the crystallization/transformation of hydrothermal synthesis alkali-activated fly ash-based zeolite

Zeolites with unique framework structure have wide applications, such as ions’ exchangers, molecular sieves and catalysts. This work focused on the synthesis and characterization of zeolite by recycling coal fly ash as the starting material via hydrothermal method. The intermediate phases and final products were characterized by XRF, XRD, FT-IR, SEM and BET techniques. The effects of aging time on the crystallization/transformation of zeolite were discussed. The results showed that the alkali-activated coal fly ash after hydrothermal process could lead to the formation of zeolite Na-P1. Furthermore, the aging treatment benefited the formation of homogenous zeolite Na-P1 with smaller particle size, larger specific surface area, total pore volume and pore size.

Ultrasonic-Assisted Hydrothermal Synthesis of Nap Zeolite and Doping with Cu or Fe for Effective Removal of Organic Dyes in Fenton-Like Oxidation Systems

Ultrasonic-Assisted Hydrothermal Synthesis of Nap Zeolite and Doping with Cu or Fe for Effective Removal of Organic Dyes in Fenton-Like Oxidation Systems

Functionalization of Zeolite NaP1 for Simultaneous Acid Red 18 and Cu(II) Removal.

The efficiency of azo dye Acid Red 18 (AR18) and Cu(II) ions simultaneous removal from an aqueous solution on NaP1CS and NaP1H was investigated, taking into account the effect of the phase contact time, pH, initial concentration, temperature, and interfering ions presence. Zeolite denoted as NaP1CS was modified by chitosan (CS) and zeolite denoted as NaP1H was modified by hexadecyltrimethylammonium bromide (HDTMA). In order to characterize sorption properties of NaP1CS, the obtained sorbent was characterized using Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption/desorption (ASAP). The kinetic parameters were determined by means of the pseudo first order (PFO), pseudo second order (PSO), and intraparticle diffusion (IPD) kinetic models. To present the adsorption data, three different isotherm models (Langmuir, Freundlich and Dubinin-Radushkevich) were used. The desorption process was also examined. It was found that for sorbent NaP1CS the pseudo second order (PSO) kinetic model and the Langmuir isotherm fitted best the experimental data. Moreover, it was noted that the acidic pH is appropriate to achieve the best sorption properties of NaP1CS for Cu(II) and NaP1H for AR18 and Cu(II). The thermodynamic parameters indicate an endothermic process. The most effective solution for the desorption process was found to be 1 M HCl. The results indicate that simultaneous removal of dye AR18 and Cu(II) on modified zeolite NaP1CS or NaP1H is possible and proceeds with a very good efficiency. The obtained zeolites could effectively adsorb AR18 an Cu(II) simultaneously, but their adsorption abilities were rather different.

Hydrothermal synthesis and characterisation of zeolites from metakaolin and water glass

Zeolites were synthetised from two types of metakaolin mixed with water glass and in some samples with water. The mixtures were autoclaved for 24 hours at 130°C. Autoclaved samples were ground to analytical fineness and tested by X-ray diffraction and differential thermal analysis. Polished samples embedded in epoxy resin were studied using of electron microprobe including BSE imaging and WDX analysis of chemical composition of zeolites. Samples with the highest zeolite content were studied by SEM. The obtained results showed that the dominant synthetised zeolite in autoclaved samples is mineral chemically close to chabazite, less phillipsite. Zeolite Na-P1, gmelinite and boggsite were also identified by XRD analyses. The total content of zeolites is up to 29 wt. % in the sample prepared from a mixture containing metakaolin MK1/sodium water glass/water in weight ratio 1.5/2.5/1. The Si/Al of synthetised zeolites varies between 2.1 and 3.2.

Alkaline Hydrothermal Synthesis of Zeolite from Class F Coal Fly Ash

Coal Fly ash is an industrial waste produced from coal-based thermal power plants. Of the total amount of fly ash generated, a small fraction is used as a supplement to Portland cement and rest of the fly ash is used as landfill. One of the novel ways of utilizing coal fly ash is through zeolitization, zeolites being hydrated aluminosilicates, and coal fly ash a rich source of alumina and silica. Coal fly ash obtained from the thermal power plant of NTPC Kaniha is subjected to alkaline hydrothermal treatment and the resulted zeolite is characterized for chemical analysis, crystal structure, thermal stability, FTIR studies, ion exchange capacities, etc. After zeolitization surface area of the product increases due to the formation of more pores and channels and also there is an increase in its crystallinity. When subjected to temperature its crystallinity first increases and then decreases and after a particular temperature the crystalline character almost vanishes. The resulted zeolite is found to be NaP1 zeolite with a high ion exchange capacity. High cation exchange (CEC) values ensure the adsorption of heavy metals by zeolites which can be used for the treatment of wastewater and industrial waste material. Thus zeolites can be hydrothermally synthesized from an industrial waste like coal fly ash at a much cheaper cost of production. The synthesized zeolite can be used for cation exchange, adsorption catalysis, and a host of other industrial applications.

Application of different alkaline materials as polluted soil amendments: A comparative assessment of their impact on trace element mobility and microbial functions

Treatment with chemical amendments is among the best techniques to remediate soils highly polluted with trace elements. The use of waste-derived products has several advantages in this regard, mainly in terms of reducing process costs and conserving natural resources. In this study, the performance of the synthetic zeolite NaP1 derived from coal combustion fly ash (SZ) and the by-product generated from the processing of aluminum salt slags (BP) was evaluated with this aim in comparison to calcite (CC). For this purpose, mine soils polluted with Zn, Cd, and Pb were amended under controlled laboratory conditions with different doses (0%, 1%, 2%, 5%, and 10%) of SZ, BP, or CC, and their impact on trace element mobility and microbial functions was evaluated. Specifically, the mobile and mobilizable trace element pools, basal soil respiration, and different enzyme activities were analyzed. Both SZ and BP performed better than CC in the immobilization of trace elements, reaching, respectively, mobility decreases up to 89–94% and 66–87% when applied at a dose of 10%. These amendments reduced the mobile trace element pool by precipitating them as acid-soluble precipitates and/or retaining them in the reducible fraction of soils. The alkaline nature of these materials and the concomitant increase in soil pH caused by their application mainly accounted for this behavior. Additionally, soil microbial functionality improved after amendment, especially in the case of SZ, as shown by dehydrogenase and alkaline phosphatase activities, which significantly increased (p < 0.05) up to 536% and 48%, respectively. Therefore, applying SZ or BP as soil amendments can significantly decrease the mobile trace element contents of heavily polluted soils without negatively affecting soil quality, thus facilitating plant growth to revegetate and reclaim degraded spaces.

NaP1 zeolite synthesized via effective extraction of Si and Al from red mud for methylene blue adsorption

NaP1 zeolite, using red mud (RM) as raw material, was successfully prepared via alkali fusion and hydrothermal method. NaP1 zeolite, which was a mesoporous material, had specific surface area and pore diameter of 79.3 m2·g−1 and 7.26 nm, respectively. NaP1 zeolite had excellent adsorption properties. Under the optimum adsorption conditions, methylene blue (MB) was adsorbed through NaP1 zeolite, the adsorption capacity was 48.7 mg·g−1 and the removal efficiency was 97.1%. The adsorbent was regenerated with sodium chloride as eluent. The adsorption capacity of the adsorbent regenerated three times still was satisfactory 34.53 mg·g−1, which showed the excellent stability performance from NaP1 zeolite. The adsorption conformed to the pseudo second order kinetic and Freundlich isotherm model. Moreover, MB molecules were adsorbed by diffusion on the outer surface, diffusion on the inner surface, and adsorption on the inner surface of NaP1 zeolite. And, during the external diffusion, electrostatic attraction and hydrogen bonding created. Al and Si were extracted from RM to prepare NaP1 zeolite with excellent adsorption properties. This result provides an important example for the development of the potential value of RM.

Tunability of ammonia adsorption over NaP zeolite

Porous adsorbents represent an environmentally-friendly and cost-effective alternative for NH 3 separation from H 2 and N 2 , particularly in the highly energy intensive Haber-Bosch process. Zeolites are deep-rooted in the world of chemical processes due to their chemical, structural, thermal stabilities, and wide variety of pore architectures. Zeolite NaP with a limiting pore of ~2.9 Å, is highly appealing for small molecule separations, in particular for potentially sieving NH 3 from N 2 and H 2 . Herein, we demonstrate the modulable and selective ammonia adsorption over nitrogen and hydrogen of Zeolite NaP. The use of different aluminum precursors led to tunable ammonia uptakes. Zeolite morphology, acidity, crystallinity, and textural properties greatly influenced the observed NH 3 uptakes. Zeolite NaP synthesized using aluminum isopropoxide, displayed high adsorption selectivities of NH 3 /H 2 = 152, and NH 3 /N 2 = 50. Aluminum hydroxide produced a highly crystalline zeolite NaP sample displaying high NH 3 uptake of 8.47 mmol/g 273K. Mesoporosity played an important role on the NH 3 uptake over zeolite NaP. A larger pore NaY zeolite was synthesized, and used to validate the ammonia sieving effectiveness of zeolite NaP. • NaP zeolite was prepared using various aluminum sources, and sodium silicate as a silica source. • Zeolite morphology, and textural properties vary with aluminum source. • NH 3 adsorption, and adsorption selectivity was tunable depending on aluminum source. • NaP displayed high adsorption selectivities of NH 3 /H 2 = 152, and NH 3 /N 2 = 50.

Mixed-Phase Ion-Exchangers from Waste Amber Container Glass.

This study investigated the one-pot hydrothermal synthesis of mixed-phase ion-exchangers from waste amber container glass and three different aluminium sources (Si/Al = 2) in 4.5 M NaOH(aq) at 100 °C. Reaction products were characterised by X-ray diffraction analysis, Fourier transform infrared spectroscopy, 27Al and 29Si magic angle spinning nuclear magnetic resonance spectroscopy and scanning electron microscopy at 24, 48 and 150 h. Nitrated forms of cancrinite and sodalite were the predominant products obtained with reagent grade aluminium nitrate (Al(NO3)3∙9H2O). Waste aluminium foil gave rise to sodalite, tobermorite and zeolite Na-P1 as major phases; and the principal products arising from amorphous aluminium hydroxide waste were sodalite, tobermorite and zeolite A. Minor proportions of the hydrogarnet, katoite, and calcite were also present in each sample. In each case, crystallisation was incomplete and products of 52, 65 and 49% crystallinity were obtained at 150 h for the samples prepared with aluminium nitrate (AN-150), aluminium foil (AF-150) and amorphous aluminium hydroxide waste (AH-150), respectively. Batch Pb2+-uptake (~100 mg g−1) was similar for all 150-h samples irrespective of the nature of the aluminium reagent and composition of the product. Batch Cd2+-uptakes of AF-150 (54 mg g−1) and AH-150 (48 mg g−1) were greater than that of AN-150 (36 mg g−1) indicating that the sodalite- and tobermorite-rich products exhibited a superior affinity for Cd2+ ions. The observed Pb2+- and Cd2+-uptake capacities of the mixed-product ion-exchangers compared favourably with those of other inorganic waste-derived sorbents reported in the literature.

NaP1 zeolite membranes with high selectivity for water-alcohol pervaporation

Membrane pervaporation is an emerging technique for the separation of water from alcohols, and zeolites with ordered ultramicropores (pore size <0.7 nm) have shown particular promise for use as membrane materials. This is the first paper to propose the use of NaP1 zeolite in membrane pervaporation. NaP1 zeolite has a GIS type topology with an 8-member ring that forms a pore limiting diameter of 3.0 Å, which is ideal for the separation of water from alcohols. NaP1 zeolite membranes with various Si/Al ratios (1.9, 3.3, and 3.9) were made via the seeded growth. Pervaporation tests were performed using an aqueous feed solution of 90 wt% ethanol or IPA at 348 K. The sample with a Si/Al ratio of 3.3 achieved separation factors surpassing most existing zeolite membranes: water/ethanol (200,000) and water/isopropanol (36,000). Nano-beam X-ray diffraction was used to map grain sizes in membrane samples, due to its role in surface hydrophilicity. State-of-the-art molecular simulations provided valuable insights into the diffusion and adsorption of water/alcohol molecules in NaP1 zeolite. From simulations, NaP1 zeolite presented a high water diffusivity and a high adsorption selectivity of water over ethanol or isopropanol. Experiment and computation results demonstrate the potential of NaP1 zeolite as a membrane material for alcohol dehydration.