Ammonium Adsorption Process Research Articles

Biochar Microparticles from Pomegranate Peel Waste: Literature Review and Experiments in Isotherm Adsorption of Ammonia

This research aimed to synthesize biochar microparticles from pomegranate peel waste for ammonia adsorption. This research also focused on analyzing adsorption isotherm and kinetics models to understand the mechanism of ammonia adsorption on the biochar. The experiments were conducted by carbonizing pomegranate peel waste. The carbonized material was then milled and sieved to obtain biochar microparticles with a certain size (i.e. 500, 1000, and 2000 μm). The particles were then characterized using microscopy and infrared spectroscopy (FTIR) to identify particle morphology and functional groups. The prepared particles were then used for the ammonium adsorption process, and compared with ten isotherm models (such as Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Jovanovic, Halsey, Harkin-Jura, Flory-Huggins, Fowler-Guggenheim, and Hill-Deboer) to identify the adsorption mechanism. Adsorption kinetic analysis was also performed to identify the adsorption rate of the prepared particles using first-order and second-order pseudo-kinetic models. The adsorption isotherm model informed that ammonia adsorption on biochar with sizes of 2000 μm (large) and 1000 μm (medium) occurs in a multilayer process with physical interaction accompanied by pore filling. Meanwhile, small biochar (500 μm) indicates that the ammonia adsorption process occurs on homogeneous sites with physical interaction through pore filling. From the results of fitting the isotherm model, information about the maximum adsorption capacity for each size of 2000, 1000, and 500 μm are 65.631, 62.231, and 50.086 mg/g, respectively. Overall, the adsorption mechanism occurring on biochar involves interactions among ammonia molecules that repel each other under endothermic conditions. The largest adsorption capacity was obtained for biochar with sizes of 2000 μm. Analysis of adsorption kinetics showed that the adsorption process follows a first-order pseudo-kinetic model, indicating an adsorption mechanism controlled by intraparticle diffusion. This study concludes that biochar from pomegranate peel is prospective for use as an environmentally friendly adsorbent for ammonia removal applications from wastewater, offering a sustainable and effective alternative adsorbent to existing water treatment technologies and solving current issues in the sustainable development goals (SDGs).

Surface Modification of Polyurethane Sponge with Zeolite and Zero-Valent Iron Promotes Short-Cut Nitrification.

Partial nitrification-Anammox (PN-A) is a cost-effective, environmentally friendly, and efficient method for removing ammonia (NH4+-N) pollutants from water. However, the limited accumulation of nitrite (NO2--N) represents a bottleneck in the development of PN-A processes. To address this issue, this study developed a composite carrier loaded with nano zero-valent iron (nZVI) and zeolite to enhance NO2--N accumulation during short-cut nitrification. The modified composite carrier revealed electropositive, hydrophilicity, and surface roughness. These surface characteristics correlate positively with the carrier's total biomass adsorption capacity; the initial adsorption of microorganisms by the composite carrier was increased by 8.7 times. Zeolite endows the carrier with an NH4+-N adsorption capacity of 4.50 mg/g carrier. The entropy-driven ammonia adsorption process creates an ammonia-rich microenvironment on the surface of the carrier, providing effective inhibition of nitrite-oxidizing bacteria (NOB). In tests conducted with a moving bed biofilm reactor and a sequencing batch reactor, the composite carrier achieved a 95% NH4+-N removal efficiency, a NO2--N accumulation efficiency of 78%, and a doubling in total nitrogen removal efficiency. This composite carrier enhances NO2--N accumulation by preventing biomass washout, inhibiting NOB, and enriching PN-A functional bacteria, suggesting its potential for large-scale, stable PN-A applications.

Multifunctional Eco-Friendly Adsorbent Cryogels Based on Xylan Derived from Coffee Residues.

Agricultural and animal farming practices contribute significantly to greenhouse gas (GHG) emissions such as NH3, CH4, CO2, and NOx, causing local environmental concerns involving health risks and water/air pollution. A growing need to capture these pollutants is leading to the development of new strategies, including the use of solid adsorbents. However, commonly used adsorbent materials often pose toxicity and negative long-term environmental effects. This study aimed to develop responsive eco-friendly cryogels using xylan extracted from coffee parchment, a typical residue from coffee production. The crosslinking in cryogels was accomplished by "freeze-thawing" and subsequent freeze-drying. Cryogels were characterized in terms of morphology by using scanning electron microscopy, porosity, and density by the liquid saturation method and also moisture adsorption and ammonia adsorption capacity. The analysis showed that the porosity in the cryogels remained around 0.62-0.42, while the apparent densities varied from 0.14 g/cm3 to 0.25 g/cm3. The moisture adsorption capacity was the highest at the highest relative humidity level (80%), reaching 0.25-0.43 g of water per gram of sample; the amount of water adsorbed increased when the xylan content in the cryogel increased up to 10% w/v, which was consistent with the hygroscopic nature of xylan. The ammonia adsorption process was modeled accurately by a pseudo-second-order equation, where the maximum adsorption capacity in equilibrium reached 0.047 mg NH3/g when xylan reached 10% w/v in cryogels, indicating a chemisorption process. The cryogels under investigation hold promise for ammonia adsorption applications and GHG separation, offering a sustainable alternative for gas-capturing processes.

Enhanced Ammonium Adsorption from Aqueous Solutions Using Ethylenediaminetetraacetic Acid (EDTA) Modified Lampung (Indonesia) Natural Zeolite: Isotherm, Kinetic, and Thermodynamic Studies

The environmental concern related to excessive ammonium in water bodies necessitates efficient and cost-effective removal techniques. This study investigated the modification of natural zeolite collected from the Tanggamus district of Lampung Province, Indonesia, with ethylenediaminetetraacetic acid (EDTA) to enhance its performance for ammonium adsorption from aqueous solution. The modified and natural zeolites were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), N2 adsorption-desorption isotherm, and scanning electron microscopy (SEM). Results indicated that the modification did not cause significant structural changes but increased the mesoporosity of the zeolites, which was beneficial for ammonium adsorption. The adsorption studies revealed that the EDTA modified zeolites consistently outperformed the natural zeolite and that the adsorption process was exothermic in nature. The Langmuir and Freundlich isotherm models fit the adsorption data well, indicating that the adsorption process occurs on both homogenous and heterogeneous surfaces. Thermodynamic studies confirmed that the adsorption process was exothermic and that the EDTA modification increased the spontaneity of the ammonium adsorption process. Overall, this study highlights the potential of EDTA-modified zeolites as an effective material for ammonium removal from aqueous solutions.

Adsorption and Desorption Behaviors of Ammonia on Zeolites at 473 K by the Pressure-Swing Method.

Adsorption and desorption behaviors of ammonia on the zeolites were investigated using the pressure-swing method to utilize the ammonia adsorbent at 473 K. For various (Y, A, L, and mordenite) types of zeolites, the effects of their pore sizes, countercation species, and number of adsorption sites on the ammonia adsorption behavior were evaluated. The adsorption capacity increased with increasing the pore size. The differences in the countercation species and the number of adsorption sites contributed to the ammonia adsorption process on the zeolites. Sodium cations strongly adsorb ammonia molecules. The adsorption/desorption of ammonia expanded and shrunk the zeolite crystal, suggesting that the pores in the zeolite were enlarged by the adsorption of ammonia molecules. Despite repetitive lattice expansion and shrinkage, the morphologies of the zeolite particles were not degraded. These results confirm that the zeolite showed high durability for the adsorption and desorption of ammonia at 473 K.

Red Seaweed (Gracilaria verrucosa Greville) Based Polyurethane as Adsorptive Membrane for Ammonia Removal in Water

Polyurethane membranes are widely developed polymers by researchers because they can be made from synthetic materials or natural materials. Red seaweed (Gracilaria verrucosa Greville) is a natural material that can be developed as a raw material for polyurethane membranes. This study used red seaweed biomass (RSB) as a raw material to manufacture polyurethane as an adsorptive membrane for removing ammonia in water. The membrane composition was determined using the Box–Behnken design from Response Surface Methodology with three factors and three levels. In the ammonia adsorption process, the adsorption isotherm was determined by varying the concentration, while the adsorption kinetics was determined by varying the contact time. Red seaweed biomass-based polyurethane membrane (PUM-RSB) can adsorb ammonia in water with an adsorption capacity of 0.233 mg/g and an adsorption efficiency of 16.2%. The adsorption efficiency followed the quadratic model in the Box–Behnken design, which resulted in the optimal composition of RSB 0.15 g, TDI 3.0 g, and glycerin 0.4 g with predicted and actual adsorption capacities of 0.224 mg/g and 0.226 mg/g. The ammonia adsorption isotherm using PUM-RSB follows the Freundlich isotherm, with a high correlation coefficient (R2) of 0.977, while the Langmuir isotherm has a low R2 value of 0.926. The Freundlich isotherm indicates that ammonia is adsorbed on the surface of the adsorbent as multilayer adsorption. In addition, based on the analysis of adsorption kinetics, the adsorption phenomenon follows pseudo-order II with a chemisorption mechanism, and it is assumed that the bond that occurs is between the anion –SO42− with the NH4+ cation to form ammonium sulfate (NH4)2SO4 and between isocyanates (NCO) with NH4+ cations to form substituted urea.

An Investigation into the Adsorption of Ammonium by Zeolite-Magnetite Composites

The discharging of ammonium from industrial, domestic, and livestock sewage has caused eutrophication of the water environment. The objectives of this study are to synthesize magnetic zeolite (M-Zeo) by an eco-friendly, economical, and easy procedure and to investigate its suitability as an adsorbent to remove ammonium from an aqueous solution. Based on characterization from XRD, BET, and SEM-EDS, Fe3O4 was proved to successfully load on natural zeolite. The effect of pH, temperatures, reacting times, initial ammonium concentrations, and regeneration cycles on ammonium adsorption was examined by batch experiments. The ammonium adsorption process can be best described by the Freundlich isotherm and the maximum adsorptive capacity of 172.41 mg/g was obtained. Kinetic analysis demonstrated that the pseudo-second-order kinetic model gave the best description on the adsorption. The value of pH is a key factor and the maximum adsorption capacity was obtained at pH 8. By using a rapid sodium chloride regeneration method, the regeneration ratio was up to 97.03% after five regeneration cycles, suggesting that M-Zeo can be recycled and magnetically recovered. Thus, the economic-efficient, great ammonium affinity, and excellent regeneration characteristics of M-Zeo had an extensively promising utilization on ammonium treatment from liquid.

A new Method for the Removal of Ammonium from Drinking Water Using Hybrid Method of Modified Zeolites / Catalytic Ozonation

Introduction: Ammonia in form of ammonium ions is toxic and could decrease the dissolved oxygen in water and endanger the aquatic life. The aim of this study is the removal of ammonium using oxidation and adsorption by catalytic ozonation and clinoptilolite zeolite, respectively. Methods: The research method is Experimental. First, optimal pH of ammonium adsorption on carbon catalyst (5 g/L), Garmsar and Firoozkooh zeolites and oxidation were determine. Then, in catalytic ozonation process, the effect of other variables on ammonium removal efficiency such as the concentration of carbonic catalyst (0.5- 50 g/L) and the reaction time were investigated. Then the effect of retention time and adsorbent concentration on adsorption of the remaining ammonium and nitrate produced by the oxidation process using zeolites and their modifications were determined. Resuts: The results showed that optimum pH for the ammonium adsorption process by carbon catalyst, catalytic ozonation and zeolite was 8, 9 and 8, respectively. However, the optimum pH 4 was determined for nitrate removal. The highest ammonium absorption capacity was related to natural Firoozookh zeolite and 18.5 mg/g, and the effect of ligand and acid modification decreased 12 and 14% of absorbed capacity, respectively. It is also, the highest nitrate removal efficiency was related to Garmsar ligand modified zeolite (98%) and an absorption capacity of 11.2 mg/g. In the COP/absorption process the concentration of ammonium was decreased to 0.6 m /L. Conclusion: This method effectively eliminates ammonium, and the modification of zeolite with cationic surfactant increases the efficiency of nitrate removal and the concentrates of all pollutants are brought below standards.

Kinetic Study of Ammonia Removal using Activated Rice Husk

Ammonia pollution causes eutrophication and algal bloom, which eventually disrupts the marine ecosystem’s equilibrium. Efforts have been made to either recover or remove ammoniacal nitrogen from water resources. Electrochemical, precipitation, adsorption, biological and membrane technology have been developed with varying degrees of complexity and arrangement to overcome this problem. To date, adsorption is widely used to remedy water resources as it is cost and energy effective while being simple to operate and maintain. Adsorption kinetic models are important in evaluating the performance of adsorbent and reveals the adsorption mass transfer mechanism. Nevertheless, the kinetic studies reported in the literature was not complete as only a few models were considered. Meanwhile, the statistical parameter to validate the model was commonly depended on R2 value alone. The objective of this study is to provide a comprehensive kinetic study of ammonia adsorption using activated rice husk, to the readers by investigating the validity of 9 kinetic models in fitting the experimental data. All the models are validated by using R2, R2, residual sum of square (SSE) and (mean square error) MSE. Result showed > 0.99 R2 values and low R2, SSE, MSE were found for Mixed order, Ritchie’s and Elovich models. This indicates that the ammonia adsorption process was governed by the adsorption at the active sites of the adsorbent and it was mainly driven by the chemisorption.

Kinetic and isotherm studies of empty fruit bunch biochar on ammonium adsorption

The presence of excessive ammonium in wastewater due to agriculture and other industrial activities affects the aquatic plants, animals and human health. Common wastewater practice offers high cost and maintenance as well as low performance. The adsorption technique offers an efficient, economically favourable and reliable physicochemical treatment method. Despite the efficiency, the studies on Empty Fruit Bunch (EFB) biochar as an adsorbent for ammonium removal is under discovered. The conducted study described the characterization of EFB biochar together with its kinetic and isotherm studies for ammonium removal. EFB underwent conventional pretreatment using fixed bed reactor at temperature of 350, 450,550 and 650 °C for 60 min of holding time prior for characterization and kinetic studies. For characterization studies, moisture, ash and pH anlysis were performed before proceed with adsorption and kinetic studies. It was found that the increment of temperature resulted in high content of ash and low content of moisture while optimum pH was in the range of pH 7. The optimum condition for ammonium adsorption was 2.5 ppm of EFB, 0.05g of ammonia dosage and time exposure of 200 minutes. The ammonium adsorption followed the pseudo-second-order kinetic model which suggests that the ammonium adsorption process is controlled by the chemical adsorption mechanism. The finding suggests the utilization of EFB biochar as a good alternative for ammonium removal through adsorption process while increasing the biomass value.

A highly activated iron phosphate over-layer for enhancing photoelectrochemical ammonia decomposition

Environmentally friendly ammonia (NH3) decomposition has attracted a lot of interests in recent years to resolve the issue of water eutrophication from a wastewater and achieve a clean H2 storage. Here, we report a novel strategy for solar-driven ammonia decomposition by introducing a highly-activated iron phosphate (FePi) over-layer on the surface of α-Fe2O3 nanorods photoanode (FePi/Fe2O3), and innovatively propose a photoelectrochemical (PEC) ammonia degradation system with enhanced performance. After a facile electrochemical (EC) activation, the FePi over-layer is converted into FeOOH. The EC-activated over-layer provides the efficient active sites for the ammonia adsorption process, which promotes the high catalytic kinetics for ammonia oxidation reaction (AOR). Due to the synergistic effect of the electrocatalytic and the photocatalytic process, the FePi/Fe2O3 exhibits the enhanced PEC AOR performance, which competes with water oxidation reaction (WOR). Comparing to the initial concentration of ammonia, the FePi/Fe2O3 achieves a 54.4% ammonia degradation rate within 3 h at 1.23 V vs. reversible hydrogen electrode (RHE) under 1 sun illumination, which demonstrates the reliable ammonia decomposition performance. This study confirms that it is feasible to achieve PEC ammonia decomposition in an aqueous solution without chloride mediators and provides a promising strategy for the harmless treatment of ammonia wastewater.

Removal of Ammonium from Aqueous Solutions Using Zeolite Synthesized from Electrolytic Manganese Residue

This paper carried out the study on removal of ammonium from aqueous solutions by zeolite derived from electrolytic manganese residue (EMR) via a fusion method. The variables of pH, contact time, EMRZ (EMR-based zeolite) dosage, initial ammonium concentration, and competitive cations and anions on the ammonium uptake capacity were systematically investigated in an attempt to illustrate adsorption performance of EMRZ. The results show that these influence factors had a remarkable impact on the ammonium uptake capacity of EMRZ. Maximum ammonium uptake capacity was achieved at pH value 8.0, EMRZ dosage 0.2 g/100 mL, contact time 100 min, initial ammonium concentration 200 mg/L, and temperature 35°C. Under optimized conditions, ammonium uptake capacity onto EMRZ was up to 27.89 mg/g. The competitive degree of cations in ammonium adsorption process follows the sequence of Na+>K+>Ca2+>Mg2+, and the sequence of anion effect on ammonium removal onto EMRZ is CO32− > Cl− > SO42− > PO43−. The adsorption kinetic was explored and best represented by pseudo-second-order kinetic model. And the adsorption isotherm experimental data had best fitness with the Freundlich and Koble–Corrigan model, suggesting that heterogeneous uptake was the principal mechanism adopted in the process of ammonium adsorption. Moreover, calculation of thermodynamic parameters such as change in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) was carried out and it was determined to be −15.77∼−14.03 kJ·mol−1, +37.66 kJ·mol−1, and +173.38 J·mol−1·K−1, respectively. These parameters confirmed that ammonium uptake onto EMRZ was an endothermic and spontaneous process. Moreover, no obvious deterioration tendency was observed for the regenerated EMRZ compared with fresh EMRZ. These results indicate that EMRZ has wide application prospects in removing ammonium from wastewater.

Study on the removal of high contents of ammonium from piggery wastewater by clinoptilolite and the corresponding mechanisms

AbstractIn this study, a clinoptilolite was applied to remove ammonium from piggery wastewater. The performance of ammonium removal and the correspondingly mechanisms were discussed. Under the optimal conditions of clinoptilolite dosage of 12 g/L, solution pH value of 8.3, shaking speed of 280 rpm and contact time of 55 min obtained by using response surface methodology (RSM), 19.7 mg of ammonium can be adsorbed onto 1 g of clinoptilolite, which was declined when metal cations were presented in the piggery wastewater. The ammonium adsorption process by the clinoptilolite can be well fitted by Langmuir isotherm with a spontaneous nature and pseudo–second–order kinetics model. Furthermore, column study showed that to some extent, the increased flow rate was beneficial to the removal of ammonium, and the ammonium adsorption capacity of clinoptilolite in column study was much higher than those in batch study.

Entrapment of micro-sized zeolites in porous hydrogels: Strategy to overcome drawbacks of zeolite particles and beads for adsorption of ammonium ions

We have demonstrated that the entrapment of micro-sized zeolite particles (ZPs) in porous hydrogels is a promising strategy toward overcoming several drawbacks of ZPs and zeolite beads (ZBs) for adsorption of ammonium ions. The polyvinyl alcohol (PVA)-alginate-ZPs (PAZ) composite hydrogel beads with the same size as that of ZBs were prepared by physically entrapping the ZPs. On the basis of structural characterization results, the entrapped ZPs are well distributed with minimal agglomeration in the highly permeable and porous hydrogels. Unlike the ZPs, the PAZ hydrogels had good settleability and showed no significant further agglomeration of the entrapped ZPs even under high zeolite dosage conditions. Due to still high accessible surface area of the entrapped ZPs in the hydrogel, the maximum ammonium adsorption capacities of PAZ hydrogels from Langmuir isotherm were 3.4–4.3 times higher than those of ZBs. Thus, we propose that the entrapment of ZPs in highly porous hydrogel has much less adverse effects on the adsorption capacity, compared to the binder commonly used in the synthetic ZBs. Similar to the ZPs and unlike the ZBs, the ammonium adsorption process in the PAZ hydrogels was governed by chemical ion exchange mechanism and tended to be rate-limited by boundary layer diffusion and mainly intra-particle diffusion. Owing to the above-mentioned key features toward overcoming drawbacks of both the ZPs and the ZBs, the PAZ hydrogels have great potential as promising alternative zeolite-type adsorbents for a broad range of industrial applications in water purification and wastewater treatment.

The investigation into the adsorption removal of ammonium by natural and modified zeolites: kinetics, isotherms, and thermodynamics

The objectives of this study were to modify Chinese natural zeolite by NaCl and to investigate its suitability as a low-cost clay adsorbent to remove ammonium from aqueous solution. The effect of Ph on ammonium removal was investigated by batch experiments. The findings indicated that Ph has a significant effect on the removal of ammonium by M-Zeo and maximum adsorption occurred at Ph 8. Ion exchange dominated the ammonium adsorption process at neutral Ph, with the order of exchange selectivity being Na+ > Ca2+ > K+ > Mg2+. The Freundlich model provided a better description of the adsorption process than the Langmuir model. The maximum ammonium adsorption capacity was 17.83 mg/g for M-Zeo at 293K. Considering the adsorption isotherms and thermodynamic studies, the adsorption of ammonium by M-Zeo was endothermic and spontaneous chemisorption. Kinetic studies indicated that the adsorption of ammonium onto M-Zeo is well fitted by the pseudo-second-order kinetic model. Ea in the Arrhenius equation suggested the adsorption of ammonium on M-Zeo was a fast and diffusion-controlled process. The regeneration rate was 90.61% after 5 cycles. The removal of ammonium from real wastewater was carried out, and the removal efficiency was up to 99.13%. Thus, due to its cost-effectiveness and high adsorption capacity, M-Zeo has potential for use in ammonium removal from aqueous solutions.

Revealing the effect of preparation parameters on zeolite adsorption performance for low and medium concentrations of ammonium

The effect of preparation parameters on the performance of zeolite for ammonium (20–300 mg N/L) adsorption from simulated wastewater is reported. It was found that the ratios of Na2O/SiO2 and Si/Al had a more important influence than crystallization time on zeolite adsorption properties. Relatively low Na2O/SiO2 ratios were beneficial for fabrication of zeolites with high proportions of micropore area and volume, which led to the surface adsorption mechanism being dominated by surface free energy and pore effects. However, with decreasing Si/Al ratios, the effect of ion-exchange was more prominent due to the high negative surface potential of zeolite. In addition, the concentration of weak acid sites on the zeolites was increased with lower ratios of Na2O/SiO2 and Si/Al, which may promote ammonium removal. Therefore, the most effective zeolite for ammonium removal, which was fabricated at Na2O/SiO2 = 1.375, Si/Al = 4 and crystallization time of 48 hr, exhibited the cooperative effects of adsorption, ion-exchange and a large amount of weak acid sites. The maximum ammonium adsorption capacity (35.06 ± 0.98 mg/g) and the removal efficiency (94.44% ± 4.00%) were obtained at the dosage of 4.0 g/L zeolite NaX at ammonium concentrations of 300 mg N/L and 20 mg N/L, respectively. The Freundlich isotherm and pseudo-first-order kinetics models provided excellent fitting for the ammonium adsorption process. In addition, zeolite NaX showed about 1.23–3.2 times the ammonium adsorption capacity of clinoptilolite. The stable and efficient reusability of zeolite NaX after five regeneration cycles demonstrated that this adsorbent has considerable potential for practical industrial applications.

Enhanced bio-methane production from ammonium-rich waste using eggshell-and lignite-modified zeolite (ELMZ) as a bio-adsorbent during anaerobic digestion

Abstract In this study, a calcium-rich natural material utilized bio-adsorbent, composed of eggshell-and lignite-modified zeolite (ELMZ) was developed for enhancing methane production at high ammonia concentrations. The ELMZ showed a maximum NH4+-N adsorption capacity of 55 mg/g, which was 5.9 folds of the natural zeolite (9.2 mg/g) and 1.4 folds zeolite modified by calcium chloride (40 mg/g), respectively. The ammonium adsorption process well fitted the pseudo-second-order kinetic model and the Freundlich isotherm. It indicated that its process was an ion-exchange process. The high abundance of cations, especially high Ca2+ in ELMZ supported the ion-exchange, which stimulated the anaerobic digestion process. The anaerobic digestion with ELMZ as a fixed-bed (initial NH4+-N concentration: 4.1 g/L), exhibited the best performance at methane yield of 250 mL CH4/g-DOCremoval, which is 7 folds higher than that achieved with natural zeolite (32 mL/g-DOCremoval) at the same ammonia level. As a bio-adsorbent, ELMZ contributes to enhance methane production and further benefits to a sustainable process since the eggshell waste is re-circulated.

Ion-exchange Capability for Ammonium Removal using Zeolite Modified by Potassium Permanganate

In this study, the ability to remove ammonium aqueous solutions of the natural zeolite particles produced in Jinzhou, Liaoning and the zeolite particles modified by potassium permanganate were characterized by using the static adsorption experiments. The results showed that ammonia adsorption capacity of natural zeolite is preferable, and adsorption capacity of the zeolite particles modified by potassium permanganate is slightly lower, but still maintain preferential adsorption. In addition, the Freundlich isotherm model proved a better fit inthe description of ammonia adsorption process than Langmuir model both for the natural zeolites and zeolite particles after potassium permanganate treatment, with R2 ranging from 0.9328 to 0.9893. The adsorption kinetic data of ammonium onto the zeolite particles modified by potassium permanganate could be welldescribed by a pseudo-second-order kinetics equation.

Capability of Ammonium Adsorption by Anaerobic Ammonia Oxidation Granular Sludge

Nitrogen removal by anaerobic ammonia oxidation (anammox) of granular sludge is a globally important emerging technology. The ammonium adsorption properties of anammox granular sludge were studied at varying initial ammonium concentration and sludge concentration. Factors affecting the absorption process as temperature, pH, salinity, and metal cations were also examined. The experimental results indicated that ammonium adsorption by anammox granular sludge occurred quickly (in about 20 min). The optimal pH was 7.0 and the ammonium adsorption process was significantly affected by temperature, salinity, and metal cations. The experimental data were modeled using Langmuir, Freundlich, and Temkin adsorption isotherms and the ammonium adsorption process was fit to the Freundlich isotherm. The kinetic results indicated that the experimental data fit well to a pseudo-second-order model. Both intraparticle diffusion and boundary layer diffusion could affect the ammonium adsorption rate. The thermodynamic parameters ΔG0, ΔH0, and ΔS0 were evaluated and suggested that ammonium adsorption was spontaneous and exothermic. These findings indicate that the adsorption of ammonium should be incorporated into models for nitrogen removal, particularly for the use of anammox granular sludge.

Covalent Organic Framework (COF-10)를 이용한 암모니아 흡착 및 탈착에 관한 연구

수소가 청정 에너지 원으로서의 중요성이 증가하면서 수소의 생산원인 암모니아 기체가 큰 주목을 받고 있다. 그러나 암모니아가 금속을 잘 부식시키고 유독성을 가지고 있기 때문에 암모니아의 저장과 운반을 가능하게 하는 흡착제의 연구가 다각도로 진행되고 있다. 이 중 공유결합 유기구조 물질(covalent organic framework)의 하나인 COF-10은 붕소를 포함한 큰 기공을 가진 물질이다. 암모니아 흡착과정에서 COF-10의 구조 안에 있는 붕소는 루이스 산으로 작용하여 암모니아와 강한 결합을 한다. 본 논문에서는 이러한 COF-10을 합성하여 BET, XRD, FT-IR을 통해 구조를 확인한다. 또한 TPD와 등온 흡착 실험을 통해 실제 암모니아의 흡착능력에 대한 분석을 진행하였다. COF-10는 9.79 mmol/g으로 우수한 암모니아 흡착 능력을 보였으며 암모니아 흡착제로서 활용 가능할 것으로 사료된다. Ammonia gas as a hydrogen source has received great attention since the importance of hydrogen gas as a clean energy source increased. However, ammonia is toxic and corrosive to metal such that the absorbent that can store and transport ammonia became an important issue. As an effort to solve this, a large pored covalent organic framework, COF-10 was proposed as an adsorbent for storage and safe transportation of ammonia. During the ammonia adsorption process, boron in COF-10 structure can act as a Lewis acid site and bind with ammonia. In this study, COF was synthesized and its structure was identified by BET, XRD and FT-IR. The adsorption characteristics of COF were investigated by TPD and adsorption isotherm. The COF-10 showed an excellent adsorption capacity for ammonia (9.79 mmol/g) which could be utilized as an ammonia adsorbent.