Search

The effectiveness of nitrate removal was assessed in a 9.5 L packed bed column bioreactor through the evaluation of various feeding strategies and initial concentrations. The bioreactor was filled with zeolite mineral particles and initially treated with Thiobacillus denitrificans. Multiple hydraulic retention times were investigated to determine the efficiency of nitrate removal. The results demonstrate that the designed bioreactor is capable of achieving an 87% reduction in nitrate levels within a three-hour timeframe. This indicates that the bioreactor system can effectively remove nitrate ions from water, even when the initial nitrate content is as high as 400 mg/L, which exceeds the standard limit of 45 mg/L. The computational fluid dynamics (CFD) model yielded satisfactory results, confirming the effectiveness of the bioreactor design. It revealed that the optimal length of the bioreactor is suitable for influents containing 400 mg/L of nitrate. However, for influents with lower nitrate concentrations or when employing lower hydraulic retention times (HRTs), the bioreactor can be constructed with shorter heights. This CFD model can serve as a valuable tool for future studies, particularly in scaling up the bioreactor system.

The nitrate removal efficiency of a 9.5 L packed bed column bioreactor was evaluated using different feeding strategies and initial concentrations. The bioreactor was filled with zeolite mineral particles and initially treated with Thiobacillus denitrificans. Several hydraulic retention times were examined to assess the effectiveness of nitrate removal. The most favorable scenario resulted in an 87% reduction in nitrate concentration from an influent of 400 mg/L within a three-hour period. To determine the optimal length of the bioreactor, a computational fluid dynamics model was developed. By comparing simulations with experimental results, the ideal height of the bioreactor for complete denitrification was determined to be 90 cm, 45 cm, 30 cm, and 20 cm for influents with nitrate concentrations of 400 mg/L, 250 mg/L, 120 mg/L, and 80 mg/L, respectively. [ABSTRACT FROM AUTHOR]

Natural zeolite is commonly used as an adsorbent for road dust suppression due to its excellent moisture absorption properties. However, during the formation process, natural zeolite tends to accumulate some zeolite water, organic impurities, and metal cations that occupy the pore channels and cavities, thereby blocking the passage of water molecules and hindering their adsorption. This study aims to improve the weak moisture absorption rate and capacity of dust suppression asphalt mixtures caused by clogged pores and impurities in natural zeolite. To achieve this different concentrations of salt solutions (NH4Cl, NaCl, MgCl2, and CaCl2) are used as modifiers for the treatment of natural zeolite. Scanning electron microscopy and Fourier transform infrared spectroscopy are used to study the interface and functional group changes between the modified zeolite substrate and asphalt mixture. The nitrogen adsorption/desorption curves of asphalt mixtures with different dosages were obtained using a nitrogen adsorption instrument. Based on this, parameters such as the specific surface area and adsorption pore volume of natural zeolite and modified zeolite asphalt mixtures were calculated using the BET and BJH methods. A macroscopic dust suppression test was further conducted to evaluate the dust suppression effect of the modified zeolite asphalt mixture on PM10. The results show that the moisture absorption rate and capacity of the modified zeolite are significantly improved. 20wt.%CaCl2 modification performs the best, and the moisture absorption capacity of the modified zeolite can reach up 10 times that of natural zeolite. Compared to the natural zeolite asphalt mixture, the specific surface area of the modified zeolite asphalt mixture is increased by 16.52%, and the adsorption pore volume is increased by 44.9%. The addition of modified zeolite powder significantly improves the dust suppression performance of the asphalt mixture. When the dosage of modified zeolite powder reaches 80%, the dust suppression effect reaches its peak, with an improvement of 16.34%.

Abstract Despite the United Nations 2030 agenda, large number of both urban and rural dwellers in low-income countries continue to lack access to improved water. Thus, increased effort is required towards enhancing low-cost drinking water treatment technologies especially for developing countries. Slow sand filter (SSF) is one of the most commonly used low-cost and efficient technologies for treating household drinking water. However, effectiveness of SSF is substantially affected by very high turbidity and relatively large amounts of dissolved heavy metals. To enhance removal of both turbidity and heavy metals, this study optimized sand bed depth (SBD) of SSF and investigated the potential of natural zeolite from Uganda for removal of lead, arsenite (As(III)) and fluoride ions from water. To remove lead ions, the zeolite was used in its natural form. However, to remove As(III) and fluoride, the natural zeolite was modified using hexadecyltrimethylammonium bromide solution. Removal of high turbidity was found to require a large optimal SBD. Furthermore, efficiency of treating synthetic turbid water increased with increasing initial turbidity. Variation of final turbidity with SBD was found to be best described by an exponential function. Optimal SBDs on top of an underdrain gravel layer of 0.2 m were 453, 522, 561, and 580 mm for turbidity of 60, 80, 100, and 120 NTU, respectively. Optimized SBD used achieve at least 95% efficiency in removing suspended particles from water with turbidity 120 NTU was found to save up to 35% of the total cost for acquiring sand volume required by a conventional SSF. For a particular zeolite mass, removal efficiencies of lead, As(III) and fluoride generally increased with increasing contact time. Removal efficiencies of lead, As(III), and fluorides were also shown to increase with increasing zeolite mass. Lead removal efficiencies using natural zeolite were 75 and 98% under 20 and 40 min, respectively. Removal of As(III) using modified zeolite mass was 91% within contact time of 10 min. Adsorption of fluoride on modified zeolite was 80% within 5 min. Adsorption of lead, As(III), and fluorides indicated promising potential of natural zeolites from Uganda for treating polluted water.

Despite the United Nations 2030 agenda, large number of both urban and rural dwellers in low-income countries continue to lack access to improved water. Thus, increased effort is required towards enhancing low-cost drinking water treatment technologies especially for developing countries. Slow sand filter (SSF) is one of the most commonly used low-cost and efficient technologies for treating household drinking water. However, effectiveness of SSF is substantially affected by very high turbidity and relatively large amounts of dissolved heavy metals. To enhance removal of both turbidity and heavy metals, this study optimized sand bed depth (SBD) of SSF and investigated the potential of natural zeolite from Uganda for removal of lead, arsenite (As(III)) and fluoride ions from water. To remove lead ions, the zeolite was used in its natural form. However, to remove As(III) and fluoride, the natural zeolite was modified using hexadecyltrimethylammonium bromide solution. Removal of high turbidity was found to require a large optimal SBD. Furthermore, efficiency of treating synthetic turbid water increased with increasing initial turbidity. Variation of final turbidity with SBD was found to be best described by an exponential function. Optimal SBDs on top of an underdrain gravel layer of 0.2 m were 453, 522, 561, and 580 mm for turbidity of 60, 80, 100, and 120 NTU, respectively. Optimized SBD used achieve at least 95% efficiency in removing suspended particles from water with turbidity 120 NTU was found to save up to 35% of the total cost for acquiring sand volume required by a conventional SSF. For a particular zeolite mass, removal efficiencies of lead, As(III) and fluoride generally increased with increasing contact time. Removal efficiencies of lead, As(III), and fluorides were also shown to increase with increasing zeolite mass. Lead removal efficiencies using natural zeolite were 75 and 98% under 20 and 40 min, respectively. Removal of As(III) using modified zeolite mass was 91% within contact time of 10 min. Adsorption of fluoride on modified zeolite was 80% within 5 min. Adsorption of lead, As(III), and fluorides indicated promising potential of natural zeolites from Uganda for treating polluted water. [ABSTRACT FROM AUTHOR]

Based on the structural characteristics of zeolite and the kinetic mechanism of iron and manganese removal using zeolite, this article summarizes the factors of the material itself in affecting 让s iron and manganese removal performance, including manually controlling and adjusting the factors that affect zeolite synthesis, such as silicon aluminum ratio, impurity removal, alkalinity, crystallization temperature, crystallization time, and directing agent, while ensuring the basic framework of zeolite during the synthesis process, as well as pre-treatment modifications such as microwave, high temperature, coating, and chemical agent soaking ・ This article provides reference and research recommendations for future research on modified zeolites. [ABSTRACT FROM AUTHOR]

The work is aimed at research of technology of lightweight concrete with porous aggregate with improved strength characteristics to expand the field of its application in reinforced concrete structures. The lack of demand for lightweight concrete in structural construction is due to its low reliability in view of the increased ultimate deformation of compression and tension. However, as recent studies show, when taking into account the ultimate compressive strain of lightweight concrete, it is quite possible to ensure the reliability of such structures. In order to expand the scope of application of light concretes in bearing layers of multilayered enclosing and bearing reinforced concrete structures, our purpose was to determine the features of the lightweight concrete composition selection technique with improved characteristics using a porous aggregate of modified zeolite-alkaline charge. Empirical equations of dependence of lightweight concrete strength on concrete density and aggregate density as well as dependence of lightweight concrete strength on coarse aggregate volume concentration and aggregate strength were established to determine rational compositions of lightweight concrete. The possibility of producing structural lightweight concrete of strength classes B15 to B27.5, with the frost-resistance mark F₁ 150 with the use of porous aggregate modified zeolite-alkaline batch is shown.

BACKGROUND: Co-contaminated soils in rare earth mining areas, particularly with Pb and ammonia-nitrogen, present a significant environmental challenge. These contaminants have the potential for lasting, irreversible effects on both ecosystems and human health. Therefore, developing efficient, sustainable, and cost-effective soil remediation techniques is critical. Remediation in these areas is not only vital for reducing environmental pollution and protecting ecosystems but also supports sustainable mining practices and resource utilization. Current research in this field, especially regarding Pb and ammonia-nitrogen co-contamination, is limited. Zeolite adsorption, a popular method globally, is effective in treating heavy metal contamination in soils, showing superior results over lime and phosphate treatments. However, enhancing the adsorption capacity of natural zeolite is necessary, for which various modification methods are being explored. Among these, wood vinegar, a product of biomass pyrolysis, shows promise in improving pollutant removal due to its antimicrobial properties. This study explores the potential of wood vinegar as an additive to alkali-modified zeolite to stabilize heavy metals and ammonia-nitrogen in soils. OBJECTIVES: In order to tackle the remediation of co-contaminated soil in rare earth mines. METHODS: Wood vinegar, sodium hydroxide, and wood vinegar-sodium hydroxide were employed for zeolite modification, and Pb and ammonia-nitrogen speciation were determined by a continuous extraction method. Dynamic adsorption experiments were conducted to preliminarily analyze distinct modified zeolites ’ adsorption performance. Optimal mixing ratio of modified zeolites with soil samples was determined by column leaching experiments. Through indoor stabilization experiments, the stabilization effects of different modified zeolites on Pb and ammonia-nitrogen were compared, and chemical speciation changes and their environmental implications were discussed. Investigating the stabilizing impact of various modified zeolites on soil Pb and ammonia-nitrogen, including their influence on specific ammonia-nitrogen forms, was further explored. SEM, BET, and XRD analyses were employed to assess morphological changes and phase composition variations of zeolites before and after modification. Considering process and cost, alkali-modified zeolite was chosen for pilot-scale tests, verifying the stabilization efficacy of remediation materials in practical applications. RESULTS: Adsorption performance in aqueous solutions. NaOH-MZ (modified zeolite by sodium hydroxide) and NaOH-2%WV-MZ (modified zeolite by sodium hydroxide combined with 2% wood vinegar) exhibited outstanding performance in Pb removal, achieving over 94% removal from a 200mg/L initial concentration. For ammonia-nitrogen removal, NaOH-2%WV-MZ and NaOH-MZ outperformed other zeolites, with removal rates of 66% and 65% for 30 mg/L, and 44% for 100mg/L. The adsorption efficiency of modified zeolite on ammonianitrogen varied with concentration, suggesting a correlation with zeolite dosage. Increasing modified zeolite dosage can enhance adsorption efficiency, as higher concentrations of ammonia-nitrogen reach saturation more rapidly. Column leaching experiments. At a 2% addition ratio of alkali-modified zeolite in soil, the most effective reduction in available Pb and ammonia-nitrogen forms was observed. Reduction trends continued over time, with a 50% decrease in Pb available form after 40 days and a 73% decrease in ammonia-nitrogen’s available form after 6 days.　Stabilization effects on soil Pb and ammonia-nitrogen. NaOH-MZ and NaOH-2%WV-MZ exhibited stabilization effects on soil Pb and facilitated the transformation of ammonia-nitrogen. After 7 days, NaOH-MZ reduced available Pb content by 20%, and NaOH-2%WV-MZ by 26%, surpassing control and NaCl-MZ. The stabilization effect persisted over time, with optimal outcomes observed in the 6th week for 2% NaOH-MZ and NaOH-2%WV-MZ. Microscopic analysis. Alkali-modified zeolites showed structural changes favoring adsorption, with NaOH2%WV modification leading to a looser structure with enhanced adsorption potential. The alkaline modification process involves cation exchange and leaching of silica components, transforming impurities like quartz into active silicates and amorphous silica. Pilot-scale tests. In an abandoned rare earth mining area, pilot-scale tests demonstrated the efficacy of 2% alkali-modified zeolite in reducing soil ammonia-nitrogen content. After 6 months, a remarkable reduction of 94.61% was achieved, highlighting the potential of alkali-modified zeolites for sustainable soil remediation. CONCLUSIONS: Alkali and alkali-wood vinegar modifications enhanced zeolite structure, reducing impurities like quartz, and improving adsorption. Experiments show that alkali-modified zeolites, particularly at a 2% addition rate, effectively remove Pb and ammonia-nitrogen, achieving up to 50% Pb stabilization and a 94.61% reduction in ammonia-nitrogen in field trials. This research informs effective soil remediation technologies and sustainable development. While showing promise, further investigation is needed to assess long-term stability. [ABSTRACT FROM AUTHOR]

In recent years, natural occurrences and human activity have led to the flow of toxins into water, including colors, pharmaceuticals, and heavy metals. This needs good water treatment to eliminate the detrimental impacts of dyes, drugs, and toxic heavy metals in water in order to provide clean water to the environment and households. This study focused on modified zeolite adsorbents for water treatment technologies that are successful in removing various colors, pharmaceuticals, and heavy metals. Adsorption is the most effective techniques for removing dyes, drugs, and heavy metals from the wastewater. This work is to examine the literature research and development of modified zeolite adsorbents for removing colors, medicines, and heavy metals from water, with a focus on adsorption capacity, influence of pH, isotherm and kinetic model, removal efficiency, and contact time. [ABSTRACT FROM AUTHOR]

Many kinds of modified zeolite in recent years was reviewed in this paper for the research progress of nitrate adsorption treatment, from surfactant modification, modification acid solution, alkali solution and metal salt solution modified several modification methods, introduces the several methods of natural zeolite modification mechanism, and finally, the modified zeolite adsorption water nitrate pollution was discussed, the prospect of it includes searching for new modified materials and combining several different modification methods, so as to reduce the shortage of a single modification method and provide reference for the subsequent new modified zeolite methods. [ABSTRACT FROM AUTHOR]

The add让ion of adsorbents to animal feed is an effective way to reduce the adverse effects of mycotoxin pollution. In order to prepare high efficiency feed aflatoxin B1 (AFB1) detoxification agent, gra・ phene oxide/metal ion composite modified zeolite was prepared by solid phase dispersion (SSD)・ The in vitro adsorption rate of AFB1 in peanut meal in simulated gastric environment(pH =2) and intestinal environment (pH 二6. 8) was studied, and the optimal compound modified zeolite was selected, and its structure characterization and adsorption properties were studied・ The results show that graphene oxide/calcium ion modified zeolite(GO・Ca-Z) has the highest adsorption rate of AFB1 in peanut meal, and the structural characterization shows that it has rich pores・ When pH was 2 and 6・ 8, the maximum adsorption capacity of GO-Ca-Z(2* 1)(the mass ratio of GO to Ca-Z was 2: 1) was 0. 046 mg/g and 0. 036 mg/g, respectively, which was 2. 42 and 3 times higher than that of unmodified zeolite・ The adsorption process conformed to the quasimodel, indicating that chemical adsorption plays an important role in the adsorp・ tion system・ After acid soaking, the specific surface area and total pore volume of GO・Ca-Z (2* 1) increased significantly, indicating that acid treatment is beneficial to improve the adsorption properties of the materials. [ABSTRACT FROM AUTHOR]

Fluorine is a very common element in the Earth's crust and is present in the air, food, and in natural waters. It never meets in the free state in nature due to its high reactivity, and it comes in the form of fluorides. Depending on the concentration of fluorine absorbed, it may be beneficial or harmful to human health. Similar to any trace element, fluoride ion is beneficial for the human body at low levels, but as soon as its concentration becomes too high, it is toxic, inducing dental and bone fluorosis. The lowering of fluoride concentrations that exceed the recommended standards in drinking water is practiced in various ways around the world. The adsorption process has been classified as one of the most efficient methods for the removal of fluoride from water as it is environmentally friendly, easy to operate, and cost-effective. The present study deals with fluoride ion adsorption on modified zeolite. There are several influential parameters, such as zeolite particle size, stirring rate, solution pH, initial concentration of fluoride, contact time, and solution temperature. The maximum removal efficiency of the modified zeolite adsorbent was 94% at 5 mg/L fluoride initial concentration, pH 6.3, and 0.5 g modified zeolite mass. The adsorption rate increases accordingly with increases in the stirring rate and pH value and decreases when the initial fluoride concentration is increased. The evaluation was enhanced by the study of adsorption isotherms using the Langmuir and Freundlich models. The Langmuir isotherm corresponds with the experimental results of the fluoride ions adsorption with a correlation value of 0.994. The kinetic analysis results of the fluoride ions adsorption on modified zeolite allowed us to demonstrate that the process primarily follows a pseudo-second-order and then, in the next step, follows a pseudo-first-order model. Thermodynamic parameters were calculated, and the ΔG° value is found to be in the range of −0.266 kJ/mol up to 1.613 kJ/mol amidst an increase in temperature from 298.2 to 331.7 K. The negative values of the free enthalpy ΔG° mean that the adsorption of fluoride ions on the modified zeolite is spontaneous, and the positive value of the enthalpy ∆H° shows that the adsorption process is endothermic. The ∆S° values of entropy indicate the fluoride adsorption randomness characteristics at the zeolite-solution interface. [ABSTRACT FROM AUTHOR]

Natural zeolite was modified by HDTMA. The effects of mass concentration of HDTMA and particle size of zeolite on simultaneous adsorption of NH4+-N， NO3--N and PO43--P by HDTMA modified zeolite were studied. The results showed that when the zeolite particle size is 80-100 mesh and the mass concentration of HDTMA is 10g/L， the removal rates of NO3--N and PO43--P by HDTMA modified zeolite reach 87.07% and 95.24%， but the adsorption capacity of NH4+-N is significantly reduced. When the particle size of zeolite is 80-100 mesh and the mass concentration of HDTMA is 5g/L， HDTMA modified zeolite not only has good adsorption capacity for PO43--P， but also can maintain a high removal rate of NH4+-N. The adsorption of HDTMA-modified zeolite follows the Langmuir isothermal adsorption model， which is in good agreement with the quasi-second-order kinetic model. Simultaneous and efficient removal of NH4+-N， NO3--N and PO43--P in low pollution water can be realized by using HDTMA modified zeolite. [ABSTRACT FROM AUTHOR]

In the present study, the ability of a modified CaCl2 zeolite (Ca-Z) to both increase Se(IV) availability and restrict Se(VI) mobility in soils is examined. As it was resulted from batch experiments and verified by X-ray absorption fine structure (XAFS) and X-ray fluorescence (XRF) spectroscopies, higher amounts of both Se species adsorbed on Ca-Z compared to natural zeolite (Z-N) forming outer-sphere complexes while the oxidation state did not alter during agitation of samples. Thereafter, Ca-Z was incorporated in six Greek soils, divided into acid and alkaline, at a 20% (w/w) rate and a series of equilibrium batch experiments were performed with soils alone and soils-Ca-Z mixtures to investigate sorption and desorption processes and mechanisms. The acid soils, either treated with Ca-Z or not, adsorbed higher amounts of Se(IV) than alkaline ones, whereas soils alone did not adsorb Se(VI) but impressively high adsorption of Se(VI) occurred in the Ca-Z-treated soils. Desorption of Se(IV) was higher from the Ca-Z-treated soils and especially from the acid soils. Higher distribution coefficients of desorption than the distribution coefficients of sorption were observed, clearly pointing to a hysteresis mechanism. The experimental data fitted with Langmuir and Freundlich isotherms. In the presence of Ca-Z, the Langmuir qm values increased indicating higher Se(IV) retention while Langmuir bL values decreased suggesting lower bonding strength and higher Se(IV) mobility. Overall, treating the soils with Ca-Z increased Se(IV) adsorption and mobility whereas it provided sites for Se(VI) adsorption that did not exist in the studied soils. [ABSTRACT FROM AUTHOR]

Currently, the issue of eutrophication and cyanobacterial blooms persists in water bodies worldwide, prompting the exploration of various treatment methods. This study conducted a comparative analysis of eutrophic water bodies using ferric chloride-modified zeolite (FMZ) and calcium hydroxide-modified zeolite (CMZ) combined with Elodea nuttallii ( E. nuttallii ) for removal and purification effects. The results revealed that the addition of E. nuttallii had a sustained inhibitory effect on phosphorus release, maintaining stability with lower Turbidity(Tur) and stabilized pH within the range of 8.5–9. FMZ demonstrated rapid reduction in dissolved phosphorus concentration, achieving a removal rate of 96% within 3 days. The combined plant group of CMZ and FMZ exhibited synergistic effects with E. nuttallii , achieving an impressive total phosphorus (TP) removal rate of 80.13% and a total nitrogen (TN) removal rate of 48.77%. Additionally, chlorophyll a (Chl a ) concentration decreased from 100.74 ± 24.72 μ g l ^−1 to 49.96 ± 2.08 μ g l ^−1 . The phytoplankton community composition indicated that diatoms thrived in low temperatures and high NH _4 conditions. Under the same low Total Nitrogen to Total Phosphorus (TN:TP) ratio, high TP concentrations were associated with cyanobacteria dominance, while green algae dominated in other scenarios. This comprehensive approach demonstrates the potential efficacy of CMZ and FMZ combined with E. nuttallii in addressing eutrophic water bodies and mitigating cyanobacterial blooms.

Water cadmium (Cd) pollution has widely aroused concerns due to high Cd toxicity in water bodies and its serious health risks to humans. Adsorption has been identified as an effective and widely utilized technology for water purification with heavy metal pollution. To develop a newly identified adsorbent of modified zeolite that can easily and effectively purify Cd-polluted water, NaOH modification (JZ), high-temperature modification (HZ), humic acid modification (FZ), Na2S modification (SZ), and ultrasonic modification (CZ) zeolites were developed, and their appearances and adsorption and desorption characteristics were investigated. The results showed that the adsorption capacity of Cd by JZ and SZ were improved by 68.87% and 32.06%, respectively, relative to that by natural zeolite (NZ); however, HZ, FZ, and CZ decreased the adsorption capacity. JZ had a higher adsorption capacity than SZ and could remove 99.90% Cd at an initial concentration of 100 mg/L. The dominant adsorption mechanism of Cd by JZ was the chemisorption of the monolayer. The preferred temperature and pH that enhanced Cd adsorption by JZ were 25–35 °C and 4–8, respectively. With an equilibrium adsorption capacity of 9.37–9.74 mg/g at an initial concentration of 280 mg/L, JZ reached its maximum saturated adsorption capacity; compared with SZ and NZ, the adsorption capacity increase was 27.83–68.81%. The R2 fitted by JZ's Langmuir model and quasi-second-order dynamics model were both above 0.93. In summary, JZ was recognized as a novel absorbent for Cd-polluted water purification. [ABSTRACT FROM AUTHOR]

The modified zeolite supported nanoscale zero-valent iron (MZ-NZVI) composites were fabricated by the traditional NaKBH4 liquid phase on the basis o£ natural zeolite modified by high. tenipe:raIu:rE calcined (MZ). The composites were characterized by XRD and SEM, the effects of MZ, NZVI and MZ-NZVI on the removal of nitrobenzene (NB), and the effects of MZ-NZVI dosage, initial NB concentration, pH and temperature on the removal of NB in water were investigated. The results indicate that NZVI was successfully loaded on the pores and surfaces of the MZ in the form of the particles or short chains. Furthermore, NZVI was better dispersed than that of non-supported, and the agglomeration phenomenon was greatly reduced. Experimental results exhibited that MZ-NZVI had excellent removal effect on NB. Moreover, the removal of NB by MZ-NZVI reached the best when MZ-NZVI was 2. 0 g/L, the initial NB concentration was 20 mg/L, the reaction pH was 7, and the reaction temperature was 25 °C. After 60 min of reaction, NB removal by MZ-NZVI basically reached equilibrium, and the removal rate reached 96. 8%. After 120 min of reaction, the removal rate of NB could reach 99. 1%. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (AZIBs) have received a number of attention because of their high safety, low cost, environmental friendliness, and favorable specific volume capacity. However, the cycle stability of AZIBs is hindered mainly by the undesired dendrite growth and side reactions of zinc anode. Herein, aiming at the issues we prepared an organic-inorganic coating composed of polyvinyl butyral and modified zeolite (Mzeolite). The composite coating combines the barrier effect of polymer and the ion migration regulation effect of zeolite, thus protecting the Zn anode and develop a uniform Zn2+ deposition simultaneously. With the modification of the composite coating on the Zn anode, the symmetric cell displays an outstanding lifespan of more than 2500 h, and the asymmetric cell also provides 974 reversible Zn plating/stripping cycles (1 mA cm−2, 1 mAh cm−2) with an average coulombic efficiency (CE) of 99.4 %. Moreover, the assembled full cell with modified Zn anode also shows an extremely long lifespan over 8000 cycles at 5 A g−1. The exceptional electrochemical performances indicate that the design of the composite coating holds great potential in the protection of Zn anode. [Display omitted] • The modified zeolite was introduced to PVB to form a composite coating for Zn anode modification. • The composite coating can effectively inhibit the side reactions. • The introduction of modified zeolite effectively regulated the ion migration and promoted the uniform Zn2+ deposition. [ABSTRACT FROM AUTHOR]

Fluorine is a very common element in the Earth’s crust and is present in the air, food, and in natural waters. It never meets in the free state in nature due to its high reactivity, and it comes in the form of fluorides. Depending on the concentration of fluorine absorbed, it may be beneficial or harmful to human health. Similar to any trace element, fluoride ion is beneficial for the human body at low levels, but as soon as its concentration becomes too high, it is toxic, inducing dental and bone fluorosis. The lowering of fluoride concentrations that exceed the recommended standards in drinking water is practiced in various ways around the world. The adsorption process has been classified as one of the most efficient methods for the removal of fluoride from water as it is environmentally friendly, easy to operate, and cost-effective. The present study deals with fluoride ion adsorption on modified zeolite. There are several influential parameters, such as zeolite particle size, stirring rate, solution pH, initial concentration of fluoride, contact time, and solution temperature. The maximum removal efficiency of the modified zeolite adsorbent was 94% at 5 mg/L fluoride initial concentration, pH 6.3, and 0.5 g modified zeolite mass. The adsorption rate increases accordingly with increases in the stirring rate and pH value and decreases when the initial fluoride concentration is increased. The evaluation was enhanced by the study of adsorption isotherms using the Langmuir and Freundlich models. The Langmuir isotherm corresponds with the experimental results of the fluoride ions adsorption with a correlation value of 0.994. The kinetic analysis results of the fluoride ions adsorption on modified zeolite allowed us to demonstrate that the process primarily follows a pseudo-second-order and then, in the next step, follows a pseudo-first-order model. Thermodynamic parameters were calculated, and the ΔG° value is found to be in the range of −0.266 kJ/mol up to 1.613 kJ/mol amidst an increase in temperature from 298.2 to 331.7 K. The negative values of the free enthalpy ΔG° mean that the adsorption of fluoride ions on the modified zeolite is spontaneous, and the positive value of the enthalpy ∆H° shows that the adsorption process is endothermic. The ∆S° values of entropy indicate the fluoride adsorption randomness characteristics at the zeolite-solution interface.

Background and Objectives: Antibiotics are among the pollutants that have entered uncontrollably in theenvironment, and lead to serious environmental problems such as disrupting aquatic ecosystems, and causing healthproblems for humans and other organisms. Therefore, it is necessary to remove them from the environment. In thecurrent study, zeolite modified by cationic surfactant of cetylpyridinium bromide hydrate was employed as anadsorbent to remove tetracycline from the aqueous solution. Materials and Methods: In this laboratory study, the effect of main variables, including initial tetracyclineconcentration, solution pH, adsorbent dosage, and reaction time on the adsorption process was investigated.Adsorbent structural features were analyzed using FESEM, pH of zero point of charge (pHZPC), and Fouriertransform infrared spectroscopy (FTIR). Finally, isotherm and kinetics of the adsorption process were studied. Results: The removal efficiency of 99.9% was achieved under the optimum condition, including initial tetracyclineconcentration of 11.5 mg L-1, pH of 6.0, the adsorbent dosage of 4.0 g L-1, and reaction time of 50 min. Themaximum adsorption capacity (qm) was found to be 65.41 mg g-1. The adsorption process for tetracycline removalfollowed the Langmuir isotherm (R2=0.9996) and second-order kinetic model (R2=0.9957). Conclusion: The adsorption process using zeolite modified by cationic surfactant was a suitable technique with highefficiency for removing tetracycline from contaminated wastewater. [ABSTRACT FROM AUTHOR]

Most superabsorbent polymers (SAPs) are prepared based on synthetic polymers (from petroleum resources), making them costly, nondegradable, and not ecofriendly. To overcome these drawbacks, biodegradable and renewable natural materials are proposed as additions into SAPs. In this article, a new SAP composite was synthesized by using AA, AM, α-cellulose, and modified zeolite (MZE). The prepared SAP composites were analysed by FTIR spectroscopy, XRD, SEM and TGA. Then, their water absorbency and water retention capacity results were evaluated. AA and AM were successfully grafted to the α-cellulose chains, and MZE was uniformly dispersed in the SAP composite matrix as an inorganic filler, which endowed the SAP composites with a more undulant and coarser surface along with more abundant hydrophilic groups. In contrast with poly(AA-co-AM), the water absorbency of the prepared SAP composites increased by 93.88% in distilled water and 89.58% in 0.9 wt.% NaCl solution. Additionally, the water retention time of these SAP composites was 11.2 h when evaluated at 50 °C, which was a 71.79% increase. Moreover, both the Tonset and Tpeak of the prepared SAP composites slightly increased compared with those of α-cellulose-poly(AA-co-AM), showing that the introduction of MZE could slightly improve the thermal stability of the SAP composites. These novel SAP composites with their excellent water absorbency and retention capacity could be applied to the agricultural and horticultural fields as water-keeping materials. [ABSTRACT FROM AUTHOR]

Removal of dyes from solution is important and low-cost materials as adsorbents are often considered in this field. In this work, the natural zeolite (NZ) was modified by hexadecylpyridinium chloride (CPC) to improve the adsorption capacity toward Naphthol green B (NGB, metal complex dye) and the exhausted adsorbent was further explored to remove Methylene blue (MB) as secondary adsorption. The characteristics of zeolite were carried out by Fourier-transform infrared spectroscopy, X-ray diffraction and Brunauer--Emmett--Teller. The adsorption behaviors of NGB on CPC modified natural zeolite (CZ) were investigated in batch mode. The adsorption quantity toward NGB from experiments was to 20.0 mg g-1 at 313 K (pH = 7.0, dose 1.0 g L-1, dye concentration 160 mg L-1). The adsorption isotherm curves of NGB onto CZ followed Freundlich, Henry, Koble--Corrigan models while kinetic curves were described using pseudo-second-order kinetic model and Elovich equation, suggesting that chemisorption and ion exchange may exist in NGB adsorption. Then, the NGB-loaded CZ (CZ-NGB) was observed to be enough stable within a wide pH range so that the materials were suitable to be applied in secondary adsorption as a new adsorbent for MB adsorption. The Redlich--Peterson and Koble--Corrigan models were confirmed to be better to depict the MB adsorption behaviors. This indicated that MB adsorption was not homogeneous. The kinetic curves of MB adsorption were in agreement with intraparticle diffusion model and double constant. The mechanism of dyes adsorption includes electrostatic attraction, ion exchange, hydrophobic interaction and Van der Waals' force. CZ is promising to remove NGB from solution and NGB-loaded CZ is also effective to bind MB from solution. [ABSTRACT FROM AUTHOR]

Water cadmium (Cd) pollution has widely aroused concerns due to high Cd toxicity in water bodies and its serious health risks to humans. Adsorption has been identified as an effective and widely utilized technology for water purification with heavy metal pollution. To develop a newly identified adsorbent of modified zeolite that can easily and effectively purify Cd-polluted water, NaOH modification (JZ), high-temperature modification (HZ), humic acid modification (FZ), Na2S modification (SZ), and ultrasonic modification (CZ) zeolites were developed, and their appearances and adsorption and desorption characteristics were investigated. The results showed that the adsorption capacity of Cd by JZ and SZ were improved by 68.87% and 32.06%, respectively, relative to that by natural zeolite (NZ); however, HZ, FZ, and CZ decreased the adsorption capacity. JZ had a higher adsorption capacity than SZ and could remove 99.90% Cd at an initial concentration of 100 mg/L. The dominant adsorption mechanism of Cd by JZ was the chemisorption of the monolayer. The preferred temperature and pH that enhanced Cd adsorption by JZ were 25–35 °C and 4–8, respectively. With an equilibrium adsorption capacity of 9.37–9.74 mg/g at an initial concentration of 280 mg/L, JZ reached its maximum saturated adsorption capacity; compared with SZ and NZ, the adsorption capacity increase was 27.83–68.81%. The R2 fitted by JZ’s Langmuir model and quasi-second-order dynamics model were both above 0.93. In summary, JZ was recognized as a novel absorbent for Cd-polluted water purification.

Methane recovery from bio-wastes is one promising renewable energy to relieve the energy crisis faced around the world. Zeolite is one of attractive exogenous additives for promoting methane production from anaerobic digestion due to its potentials in regulating microorganism enrichment and anaerobic environment. However, the poor electron mediated ability limited its positive effects. Hence, this study hypothesized that the electron mediated ability of zeolite would be improved by loading magnetite, thereby generating more positive impacts on the performance of sludge anaerobic digestion. Compared to control group, magnetite modified zeolite (MZ) effectively improved methane yield by 37.4%. The reason was that the electron mediated ability and adsorption capacity of zeolite were improved by loading magnetite, facilitating the degradation of refractory organics and the conversion of volatile fatty acids. Moreover, the activities of cytochrome c and F420 increased by 33.3% and 29.8% with MZ additive, contributing to stimulating efficient electron transfer process. In addition, the electro-active genera were enriched, such as Bacteroidetes_vadinHA17 , Methanobacterium , and Methanosaeta , and the direct interspecies electron transfer was possibly established for methanogenesis with the help of MZ. This study will provide valuable references for the application of zeolite in anaerobic digestion. [Display omitted] [ABSTRACT FROM AUTHOR]

Zirconium-modified zeolites were prepared by an in- situ synthesis method using fly ash as the raw material, which had high Zr contents and excellent adsorption ability for As(V), and no template agent was used during preparation. In this study, Zr-modified zeolites were prepared by in- situ and ion exchange, and then the adsorption efficiency and mechanism of Zr-modified zeolites for As(V) in solution were investigated. The Zr content in the modified zeolite synthesized in- situ reached 10.83 wt%, which was higher than that of the modified zeolite prepared by ion exchange of 7.77 wt%. More Zr was introduced into the Zr-A zeolite through Zr4+ ions replacing Na+ ions to enter the anti-balance cation sites and replacing aluminum to enter the skeleton. By Langmuir model fitting, the adsorption capacity of the Zr-A zeolite for As(V) was 104.63 mg/g, which was higher than that of the ZrIE-4A zeolite (88.58 mg/g). By adsorption kinetic and thermodynamic model fitting, As(V) adsorption by Zr-modified zeolite was mainly chemisorption. FTIR and XPS analyses demonstrated that after introducing Zr, the Zr-A zeolite acted as a Lewis acid and Zr in the Zr-A zeolite could generate single- or double-dentate complexes with As(V) through internal spherical complexation. The adsorption efficiency of Zr-A zeolite for As(V) was almost unaffected by Cl-, SO 4 2-, NO 3 - and CO 3 2- but decreased with increasing PO 4 3- concentration in solution. Therefore, Zr-A zeolite with high Zr contents could be prepared directly using fly ash by simple in- situ synthesis, and it could efficiently remove As(V) in solution. • The Zr-A zeolite were synthesized in- situ using fly ash as the raw material. • Zr contents reached 10.83 wt% in the modified Zr-A zeolite. • Zr replaced anti-balanced Na+ ion and Al of skeleton to be introduced into zeolite. • Zr-A zeolite acted as Lewis acid and had an affinity for As(V) of Lewis bases. • The Zr in the Zr-A zeolite could interact with As(V) to generate complexes. [ABSTRACT FROM AUTHOR]

Nitrate removal is important for reuse of agricultural drainage, controlling nutrition and reducing its environmental impacts. For this purpose, the effect of zeolite modification with concentrations of 0, 10, 15, 20 and 25 mg/L of HDTMABr surfactant, in columns with height of 30 cm and 32 mm diameter were investigated. In order to modelling the breakthrough curve of adsorption column, three models of Bohart-Adams, Thomas and modified dose-response plus Artificial intelligence model of ANFIS were evaluated. The results showed that when the equilibrium adsorption capacity is increased from 0.07 to 0.74 mg/g, the breakthrough and exhausting times are also increased. Modification of natural zeolite with a concentration of 25 mg/L of surfactant, was selected as the best surfactant concentration. Among the adsorption models, Thomas model and the modified dose-response model were able to predict the dynamic absorption coefficients, but the modified dose-response model, was more efficient and more accurate. The results of the study showed that Increasing the concentration of surfactant leads to an increase in the equilibrium adsorption capacity. ANFIS with average relative error of 23.3%, root mean square and chi-square of 3.9 and 7.2 mg/L, had a higher efficiency than the modified response dose model, and in total has been shown higher performance to mathematical adsorption models.

Large amounts of residual 1-methylnaphthalene are generated when 2-methylnaphthalene is extracted from alkyl naphthalene. In order to transform waste into assets, this study proposes a feasible process for preparing 2-methylnaphthalene from 1-methylnaphthalene through isomerization and crystallization. The 1-methylnaphthalene isomerization was carried out in a fixed-bed reactor over mixed acids-treated HBEA zeolite. The results showed that acidic properties of catalysts and reaction temperature were associated with the 2-methylnaphthalene selectivity, yield and catalytic stability. At a high reaction temperature of 623 K, the 2-methylnaphthalene yield was 65.84 %, and the deactivation rate was much lower. The separation of reaction products was then investigated by two consecutive crystallization processes. Under optimal conditions, the 2-methylnaphthalene purity attained 96.67 % in the product, while the yield was 87.48 % in the refining process.

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The functionalized biochar was assembled on modified zeolite to synthesize a novel modified composite adsorbent. The latter was applied to simultaneous adsorption of ammonium and nitrate. The Box–Behnken design (BBD) in response surface methodology (RSM) was applied to optimize the parameters, which included ratio of raw materials, adsorbent dose, pH, and temperature. The chemical functional groups were determined by Fourier transform infrared adsorption (FT-IR). Stronger absorption peaks of amine groups indicated that the functionalized adsorbent could enhance the adsorption of contaminants. The composite adsorbent effectively increased NH4+ and NO3− adsorption capacity by porous structure recombination, change of surface morphology and further exposure of surface functional groups. The kinetic results indicate that the adsorption of both NH4+ and NO3− follows a pseudo-second-order nonlinear model. The Langmuir isotherm model fitted well the experimental data with a maximum adsorption capacity of 24.45 mg/g for nitrate and 24.63 mg/g for ammonium at 25°C. Nitrate was absorbed by electrostatic interactions with grafted amine groups and, in contrast, the ammonium adsorption was mainly related to ion exchange with Na+. The adsorption process of both nitrate and ammonium were spontaneous and exothermic. The adsorbents can be regenerated effectively in NaCl and NaOH mixed solutions, and the desorbed adsorbents are of high reusability and can be applied effectively at least for five cycles. Therefore, it has a great potential for nitrate and ammonium simultaneous removal from water environment. [ABSTRACT FROM AUTHOR]

The natural Turkish zeolite has been modified with hexadecyltrimethylammonium bromide (CTAB) for the elimination of fluoride (F−) from aqueous solutions. The parent natural zeolite (NZ) and modified zeolite (MZ) have been characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), zeta potentials and Brunauer-Emmett-Teller (BET) method. The effect of pH, adsorbent dose, contact time, initial concentration and temperature on adsorption of fluoride ions onto modified zeolite (MZ) has been determined in batch experiments. Fluoride concentration can be reduced to 1.5 mg/L under the optimum condition (pH = 5, adsorbent dose = 20 mg/L, contact time = 60 min and T = 293 K) when initial fluoride concentration of 10 mg/L is employed. The fluoride adsorption on MZ has been described by the Langmuir isotherm and the maximum fluoride adsorption capacity was found as 2.994 mg/g. Kinetics data were best described by the pseudo-second-order model. The thermodynamic studies proved that the adsorption was exothermic and spontaneous. [ABSTRACT FROM AUTHOR]

Zeolites with the three-dimensional structures occur naturally or can be synthesized in the laboratory. Zeolites have versatile applications such as environmental remediation, catalytic activity, biotechnological application, gas sensing and medicinal applications. Although, naturally occurring zeolites are readily available, nowadays, more emphasis is given on the synthesis of the zeolites due to their easy synthesis in the pure form, better ion exchange capabilities and uniform in size. Recently, much attention has also been paid on how zeolite is being synthesized from low-cost material (e.g., rice husk), particularly, by resolving the major environmental issues. Hence, the main purpose of this review is to make an effective resolution of zeolite synthesis methods together with potential applications in environmental engineering. Among different synthesis methods, hydrothermal method is commonly found to be used widely in the synthesis of various zeolites from inexpensive raw materials such as fly ash, rice husk ash, blast furnace slag, municipal solid waste, paper sludge, lithium slag and kaolin. Besides, future expectation in the field of synthetic zeolites research is also included.

Artificial zeolite was modified by nano-Fe3O4 for development of functional adsorbents. Subsequently, adsorbents such as calcium cross-linked nano-Fe3O4 microspheres (Ca-MS), calcium cross-linked nano-Fe3O4 modified zeolite microspheres (Ca-MZS) and iron cross-linked nano-Fe3O4 modified zeolite microspheres (Fe-MZS) were prepared and compared for their adsorption performance. The effects of adsorbent dosage, solution pH, initial concentration and ion content on the removal of Cu2+ from wastewater are investigated, and the adsorption kinetics and isotherms for the adsorbent materials were analyzed. The experimental results indicate that for the initial concentration of Cu2+ of 30 mg/L, the adsorption is noted to be most stable. The optimal initial pH for adsorbing Cu2+ is observed to be 5.5. At an optimal dosage of Ca-MZS of 900 mg/L, the adsorption capacity is measured to be 28.25 mg/g, along with the removal rate of 72.49%. The addition of Na+ and K+ affects the adsorption of Cu2+. For the Na+ and K+ concentration of 0.2 mmol/L, the Cu2+ removal rate by Ca-MZS drops to 11.94% and 22.12%, respectively. As compared with the adsorbents such as Natural Zeolite (NZ), Ca-MS and Fe-MZS, Ca-MZS demonstrates the best removal effect in solution, where the removal rate reaches 84.27%, with the maximum adsorption capacity of 28.09 mg/g. The Cu2+ adsorption kinetics of Ca-MZS is observed to follow the Elovich kinetic model, with the adsorption isotherm data fitting the Freundlich isotherm model by using the non-linear method. [ABSTRACT FROM AUTHOR]

Zeolite modified with phosphate (Z/P) was synthesized and tested for Th4+ adsorption. The optimum adsorption conditions are as follows: pH 3.5, contact time of 30 min, 0.1 g of Z/P, initial Th4+ concentration of 400 mg/L, 20% tributyl phosphate (TBP) in toluene as solvent, and room temperature. Kinetics and equilibrium parameters of the Th4+ adsorption onto Z/P were determined. The maximum sorption capacity determined using the Langmuir model reached 92.59 mg/g. The Th4+ adsorption onto Z/P follows a pseudo-second-order kinetic model. Th4+ can be efficiently desorbed from the loaded Z/P with 1 M HNO3 solution. The optimized conditions were applied to the thorium adsorption from a conglomerate sandstone sample of Abu El Toyour, eastern side of Wadi El Sahu, Southwestern Sinai, Egypt. [ABSTRACT FROM AUTHOR]

Tetracycline is one of the most widely used antibiotics that causes contamination of aqueous environments and has raised serious concern during the past few years. In this work, adsorption of tetracycline on a modified zeolite was studied through a batch system. Synthetic zeolite 13X was modified using Fe(III). The results show that the removal efficiency of tetracycline by modified zeolite has considerably increased. Different experiments were carried out in order to analyze the effect of parameters such as pH, initial concentration of tetracycline, time, etc. The results indicate that tetracycline adsorption on the zeolite strongly depends on the pH of the solution due to amphoteric functional groups of tetracycline and maximum adsorption capacity of tetracycline by modified zeolite with a pH of approximately 6. The Langmuir isotherm shows good agreement with the experimental data suggesting monolayer adsorption. Maximum adsorption capacity of the modified zeolite reached at the experiments is almost 200 mg/g. XRD, XRF and FTIR results confirm the existence of the Fe phase in the zeolite texture. Amide groups of TC were responsible for the complexation with Fe3+. Also, tetracycline removal was studied in a continuous column to simulate an industrial waste water process. [ABSTRACT FROM AUTHOR]

Dredging is widely used to control internal sediment nitrogen (N) pollution during eutrophic lake restoration. However, the effectiveness of dredging cannot be maintained for long periods during seasonal temperature variations. This study used modified zeolite (MZ) as a thin-layer capping material to enhance dredging efficiency during a year-long field sediment core incubation period. Our results showed that dredging alone more effectively reduced pore water N, N flux, and sediment N content than MZ capping but showed more dramatic changes during the warm seasons. The N flux in dredged sediment in summer was 1.8 and 2.5 times that in spring and autumn, respectively, indicating a drastic N regeneration process in the short term. In contrast, the combination method reduced the extra 10% pore water N, 22% N flux, and 8% sediment organic N content compared with dredging alone and maintained high stability during seasonal changes. The results indicated that the addition of MZ to the surface of dredged sediment not only enhanced the control effect of dredging by its adsorption capacity but may also smooth the N regeneration process via successive accumulation (in the channel of the material) and activation of bacteria for months, which was evidenced by the variation in microbial diversity in the MZ treatment. As a result, the combination of dredging with modified zeolite simultaneously enhanced the efficiency and stability of the single dredging method in controlling sediment N content and its release, exhibiting great prospects for long-term application in eutrophic lakes with severe pollution from internal N loading. [Display omitted] • Dredging, thin-layer capping and their combination was used to control internal N. • Dredging alone exhibited higher control efficiency than capping material alone. • Dredging showed more drastic change of N flux during warm seasons. • The combination method enhanced the effectiveness and stability of dredging alone. [ABSTRACT FROM AUTHOR]

• Ion-exchange zeolite and MgCl 2 impregnated zeolite were developed. • Sorption capacity improved by 18% for Mg-exchange and 53% for MgCl 2 impregnation. • Sorption equilibrium and kinetics of zeolites were studied. • Temperature and concentration dependence of diffusivity were discussed. Zeolite NaX is one of the most popular water sorption materials for dehumidification, thermal energy storage and sorption cooling. In this paper, zeolite NaX is modified by magnesium chloride to achieve ion-exchange (zeolite NaMgX) and salt impregnation (zeolite NaX/MgCl 2) with the aim of improving water sorption capacity and thermal performance. The pore structure, desorption heat, water equilibrium sorption property, adsorption kinetics and cycling stability of zeolite NaX, NaMgX and NaX/MgCl 2 were studied to evaluate their potential for sorption application. Experimental results show the zeolite NaMgX has stronger hydrophilic and can improve the water sorption capacity from 0.17 g/g to 0.20 g/g at 2500 Pa. The zeolite NaX/MgCl 2 with 12.6 wt% salt confined inside the meso-/macro-pore, can improve the water sorption capacity from 0.17 g/g to 0.26 g/g with sorption heat of 842 J/g. The sorption rate of zeolite NaX/MgCl 2 is much lower than that of pure zeolite NaX, while zeolite NaMgX has a slight lower sorption rate than pure zeolite NaX. The diffusivity of zeolite NaX is in the range of 8.03 × 10−10–1.97 × 10−9 m2/s at 1000–2500 Pa, while zeolite NaMgX and zeolite NaX/MgCl 2 have diffusivities in the range of 5.22 × 10−10–1.73 × 10−9 m2/s and 3.76 × 10−10–9.87 × 10−10 m2/s respectively. The diffusivities of different zeolite samples increase with temperature which can be described by activated energy factor, and the relation between diffusivity and pressure is strongly coupled with the equilibrium equation. The modified zeolites have good thermal stabilities and no obvious uptake loss after ten adsorption-desorption cycles, making them feasible, scalable and economical for sorption thermal energy storage and cooling applications. [ABSTRACT FROM AUTHOR]

The present paper reports data on the adsorption of Pb2+ and Cd2+ ions on modified zeolite from the Shankanai deposit. A non-toxic polymer, polyethylene glycol, is used as a modifier. The sorption process is carried out at 295K and pH of 7. The prepared material (sorbent) is characterized by the Brunner-Emmett-Teller method (BET), scanning electron microscopy (SEM), while the concentration of the heavy metal ions prior to and after the adsorption is measured by atomic absorption spectrometry (AAS). The static ion-exchange capacities (SEC) of the modified sorbent for removal of Pb(II) and Cd(II) are found equal to 1.44 mg/g and 0.53 mg/g, respectively. The uptake behavior of the metal ions in respect to the modified zeolite is studied depending on the contact time. It is found that the percentage of the heavy metal ions removal increases with increase of the contact time in a neutral medium with a high concentration of heavy metals (the removal efficiency amounts to 90.02% for Pb2+ and 46.31% for Cd2+). [ABSTRACT FROM AUTHOR]

The performance of a widely used commercial catalyst, NiMo/Al2O3, might be not adequate to meet more stringent regulations for the fuel products; therefore, a lot of research has been devoted to improving its performance. In this study, three different modified zeolites were added in NiMo/Al2O3 catalyst to investigate the selective improvement of the hydrodesulphurization (HDS) and hydrodenitrification (HDN) activity. The catalysts were characterized by N2 adsorption, pyridine‐infrared spectroscopy (IR), H2‐temperature program reduction (H2‐TPR), x‐ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), and their catalytic activity was tested in the HDS and HDN of light cycle oil (LCO). Characterization results revealed that the catalyst surface area increased but the pore volume and average pore size decreased by adding modified zeolite. The activity evaluation result showed that the NiMo/MB catalyst had the highest activity and meanwhile decreased the final boiling point from 520.8 to 457 °C. The sulphur decreased by 97.65 % from 13 000 to 305 ppm and the nitrogen reduced by 99.74 % from 496 to 1.29 ppm in LCO hydrotreating, notably for NiMo/MB catalyst. The acid properties indicated that zeolite brought some strong and ultra‐strong acidic sites, which might favour a cracking reaction and reduce the liquid recovery yield. However, only 1.99 and 1.34 wt% of the LCO were cracked over the zeolite beta and zeolite modified beta respectively, indicating a slight cracking process. These results suggest that an added modified beta not only raised the quality of LCO distillation but also avoided the overcracking of hydrocarbons. [ABSTRACT FROM AUTHOR]

Abstract Natural adsorbent was optimized from four natural adsorption materials (kaolin, bentonite, diatomite, and natural zeolite) through the comparison of their ability to recover organic matter from an ultra-short-sludge-retention-time (ultra-short-SRT) activated sludge process effluent. Natural zeolite was modified by the loading of three types of chemical coagulants (Fe 2 (SO 4) 3 , Al 2 (SO 4) 3 , and ZnSO 4) and was used for the study of the advanced recovery of organic matter. The results of Brunauer–Emmett–Teller surface area (S BET) measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses showed that natural zeolite was successfully modified, with decrease in the specific surface area of the modified zeolite (MZ), but some metal ions/metal oxides were loaded onto the surface of natural zeolite. Compared with chemical coagulant and natural zeolite, the organic recovery efficiency from the effluent of the MZs improved, and after the optimization process, the organic recovery efficiency of MZ4 (Zeolite:Fe 2 (SO 4) 3 = 4:1), MZ9 (Zeolite:Al 2 (SO 4) 3 = 4:1), and MZ13 (Zeolite:ZnSO 4 = 2:1) reached 72.0%, 67.6%, and 61.2%, respectively. The MZs can allow a significant amount of recovery of soluble chemical oxygen demand (SCOD) from the effluent, with SCOD recovery efficiencies for MZ4, MZ9, and MZ13 of 44.8%, 44.3%, and 39.4%, respectively. The E 4 /E 6 , UV 253 /UV 203 , and SUVA analyses after the organic recovery experiments indicated that the generation potential of disinfecting byproducts or halogenated products was reduced in the treated effluent by the MZs. The mechanism can be considered in two ways: the coagulation effect of the loaded metal ions/metal oxides and the physical and chemical adsorption effect based on the hydrogen bond and π π bond between the MZ and organic matter. This study facilitated the application of organic recovery from wastewater and the advanced treatment of effluent. Graphical abstract Unlabelled Image Highlights • Natural zeolite was successfully modified through loading the traditional chemical coagulants. • The organic recovery ability of natural zeolite was improved evidently after modification. • The MZs can allow a lot of dissolved organic matter (SCOD) recovery from effluent. • The recovery mechanism for the MZs mainly included the coagulation effect and adsorption effect. [ABSTRACT FROM AUTHOR]

The discharge of phosphorus into surface waters results in overgrowth of aquatic plants and consequent eutrophication of rivers and seawaters; thus, removing this material to prevent surface-water nutrient uptake has received researchers’ attention in recent years. The aim of the present study was to investigate the efficiency of stabilization of zeolite nanoparticles modified by cationic surfactant on pumice aggregates to remove phosphate from aquatic environments. In this study, zeolite nanoparticles, modified by CTAB surfactant, were stabilized on pumice aggregates substrate using heating operation; then, the structural and physical features of the prepared absorbent were analyzed using FTIR, XRD, SEM, and EDAX techniques. Experiments were designed using Box-Behnken response surface methodology to improve the variables. Variables of pH (5–9), temperature (15–45°C), and amount of absorbent (5–15 g/L) were investigated. In addition, in order to investigate kinetics and adsorption isotherm, separate tests were conducted to determine the optimal amount of contact time (5–150 min) and phosphate concentration (5–28 mg/L). Results show that the optimum conditions to remove phosphate by modified aggregates were measured at a pH of 5; temperature of 45°C and absorbent amount of 15 g/L. Kinetics investigations showed that phosphate removal follows the second-order model and the optimum contact time was measured at 60 min in which phosphate removal efficiency was 82.22%. The results also show that phosphate adsorption isotherm has good agreement with Langmuir isotherm. The study shows that stabilizing the modified zeolite nanoparticles using cationic surfactant on pumice aggregate is highly effective for phosphate removal, thus it can be used for removing such pollutants from aquatic environment. [ABSTRACT FROM AUTHOR]

Nanosized NaA zeolite was successfully synthesized by hydrothermal method using tetraethyl orthosilicate (TEOS) and aluminum isopropoxide (AIP) as the main raw materials. The surface modification of NaA zeolite was carried out by silane coupling agent 3-aminopropyltriethoxysilane (KH-550). The effects of silane coupling agent dosage, reaction temperature, reaction time, hydrolysis time and pH value on grafting rate of NaA zeolite were investigated in detail. The zeolites were characterized by XRD, SEM-EDS, FT-IR and TG-DTA. The results showed that the surface of NaA zeolite was modified successfully by KH-550. The optimal modification conditions obtained were as follows: the dosage of coupling agent in 95 % ethanol – 1.6 %, reaction temperature − 70 °C, reaction time – 2 h, hydrolysis time – 20 min, and pH value – 3.5. Under these conditions, the grafting rate of modified NaA zeolite was 3.95 %. [ABSTRACT FROM AUTHOR]

A high-ammonia-resistant strain was firstly isolated from activated sludge and applied to harvest a bioflocculant from a swine wastewater. Enhancement of swine wastewater treatment was investigated by a composite of the harvested bioflocculant and a zeolite modified by integrating calcinations with MgO at 400°C. Results have demonstrated that 71.8% of Chemical Oxygen Demand (COD), 54.5% of ammonia, and 81.2% of turbidity can be removed from the swine wastewater by the bioflocculant alone. Results have also demonstrated that 73.4% of ammonia could be removed from the swine wastewater by the modified zeolite alone, while almost no COD was removed. Thus, the bioflocculant and modified zeolite were used simultaneously to enhance swine wastewater treatment, and response surface methodology (RSM) was employed to optimize the treatment process. Under the optimal treatment conditions of bioflocculant of 12 mg/L, modified zeolite of 8 g/L, pH of 7.5, and agitation speed of 200 r/min, obtained by the RSM, 88.6% of COD, 85.8% of ammonia, and 95.5% of turbidity could be removed from swine wastewater, which were significantly improved compared with that by the bioflocculant or modified zeolite alone. The use of the composite exerted advantages of the bioflocculant and modified zeolite, and provided a feasible way to improve pollutants’ removal from wastewaters. [ABSTRACT FROM AUTHOR]

A kind of easily recyclable and composite photocatalyst based on Ag/AgCl/Bi 2 O 3 /BiFeO 3 (AABB) and modified zeolite (MZ)/activated carbon (AC) were made, and investigated for the degradation of levofloxacin hydrochloride (Lev-HCl) in wastewater. The structures and morphologies of AABB@loading materials were firstly characterized. The results showed that under visible light, the optimal conditions for photodegradation were: mass ratio of MZ to AABB 3:2, AABB@MZ dosage 1–1.2 g/L, initial concentration of Lev-HCl <18 mg/L. Under these conditions, 72.09%∼ Lev-HCl could be degraded within 1.5 h. In addition, AABB@MZ could be easily recovered by gravity settling for 30 min and reused three times with 74.7% recovery rate. Photoluminescence (PL) combined with electron paramagnetic resonance (EPR) showed that photocatalysts mainly produced ·O 2 − and ·OH, which played a major role in the degradation process. Finally, a possible catalytic mechanism for AABB@MZ was suggested. Preparation of AABB@MZ and its application in levofloxacin hydrochloride degradation. [Display omitted] • An easily recyclable photocatalytic composite material based on AABB was explored. • Over 72.09% Lev-HCl was degraded within 1.5 h by the AABB@MZ/light system. • The recovery rate of AABB@MZ over three cycles of gravity settlement reached 74.7%. • PL and EPR results showed that·O 2 − and ·OH played a major role in the degradation. [ABSTRACT FROM AUTHOR]

The adsorption of the acid dye Acid Orange 8 (AO8) onto unmodified and modified zeolites from coal fly ash and bottom ash was evaluated. The coal fly ash and bottom ash used in the synthesis of the zeolites by alkaline hydrothermal treatment were collected in the Thermoelectric Complex Jorge Lacerda, located in the Santa Catarina State, Brazil, the largest coal burning thermoelectric complex of Latin America. The modified zeolites were modified using the surfactant hexadecyltrimethylammonium bromide. The zeolitic materials were characterized predominantly as hydroxysodalite and NaX. The kinetics studies indicated that the adsorption followed the pseudo-second order kinetics. Linear and non-linear regression methods were used to determine the best fit of equilibrium data. The Freundlich model was better adjusted to the experimental data for all systems studied. The parameters of adsorption isotherms were used to predict the design of the equipment for performing adsorption discontinuous single stage. DOI: http://dx.doi.org/10.17807/orbital.v7i4.764