Adsorption Of Ammonium Ions Research Articles

Exploring ammonia adsorption and filtration efficiency of ceramic membranes derived from weathered basalt: Fabrication analysis and application in wastewater treatment

This study aims to develop an innovative ceramic membrane derived from naturally-occurring weathered basalt (NWB) for the effective adsorption and filtration of ammonium ions (NH+4) from wastewater. The NWB was subjected to calcination to produce CWB-750 and further combined with activated carbon to form CWB-AC-950. Comprehensive characterization using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) analysis revealed that CWB-AC-950 possessed a significantly high surface area of 121.7 m²/g and a minimal pore volume of 6.2 nm, indicating its enhanced adsorption capabilities. In practical filtration tests, CWB-AC-950 demonstrated a remarkable reduction in NH+4 concentration, decreasing it from an initial 30 mg/L to 15.25 mg/L. This substantial decrease underscores the membrane's efficiency in adsorbing and removing ammonium ions from contaminated water. Furthermore, the integration of activated carbon with calcined basalt not only improved the adsorption performance but also maintained the structural integrity and reusability of the membrane. These findings illustrate the potential of CWB-AC-950 as a promising and cost-effective medium for adsorption and filtration in wastewater treatment applications.The development of CWB-AC-950 contributes significantly to environmental remediation efforts by offering an efficient and low-cost alternative to conventional filtration materials. Its ability to maintain performance across multiple cycles underscores its potential for practical applications in large-scale wastewater treatment facilities, thus providing a sustainable solution to address the growing global water pollution crisis.

Performance Evaluation of a Romanian Zeolite: A Sustainable Material for Removing Ammonium Ions from Water

Ammonium ion is a chemical species that is found in abundance in natural waters, whether underground or surface, but also in wastewater resulting from agricultural and industrial activities. Even if the removal of the ammonium ion from water has been studied for a very long time, it has been found that its removal is far from being solved. In this study, we evaluated the performance of the ammonium ion adsorption process on two adsorbents, zeolite clinoptilolite, ZR, a sustainable material (manufacturer: Zeolite Development SRL, Rupea, Brasov, Romania), and the other granular activated carbon type, Norit GAC 830 W. Zeolite ZR is found in very large deposits in Romania; it is a natural, cheap material with costs between 50 and 100 EUR/ton, compared to other adsorbents that cost over 500 EUR/ton and which can be regenerated and reused in the technological process of water treatment and purification, but also after exhaustion, as an amendment for the soil. In the first step, this paper presents the mineralogic (XRD) and structural (SEM and EDX) characterization of the ZR and the determination of the pH zero-point charge, pHZPC, for all the adsorbents. Studies were carried out in equilibrium and kinetic conditions. The efficiency of the adsorbent was investigated in different experimental conditions by varying the initial concentration, particle size, temperature, pH, ionic strength, and contact time. The mathematical models and parameters specific to the adsorption isotherms that best describe the experimental results were identified. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich mathematical models were used for comparison. The Langmuir isotherm proved to be the most appropriate to describe the adsorption of ammonium ions on all types of adsorbents used. The adsorption capacity of ammonium ions from synthetic solutions at 20 °C, pH = 6.09, for the range of initial concentrations 0–50 mg/L for Rupea zeolite is in the range of 10.46 mg/g−12.34 mg/g, and for granular activated carbon GAC W830, it is 16.64 mg/g. It was found that the adsorption capacity of the ammonium ion on both activated carbon and zeolite increases with increasing temperature and pH. Also, it was observed that as the ionic strength increases, the adsorption capacity decreases for all four adsorbents. Kinetic models were also identified that best describe the experimental processes. In this sense, pseudo-first order, pseudo-second order, intra-particle diffusion and the Elovich model were used. The results of the investigation showed that second-order kinetics governs the adsorption process on ZR, and pseudo-first order governs activated carbon.

Regulation of Electron Delocalization Region in 2D Heteroligand-Based Copper-Organic Framework to Enhance Charge Storage.

The rechargeable aqueous ammonium ion battery shows great potential in low-cost energy storage system because of its long life and environmental friendliness. However, most inorganic host materials used in ammonium ion batteries are still limited by slow diffusion kinetics. Herein, it is identified that a 2D heteroligand-based copper-organic framework featuring numerous ammonium ion adsorption site in the π-conjugated periodic skeleton supplies multiple accessible redox-active sites for high-performance ammonium storage. Benefitting from the effective regulation of electron delocalization by heteroligand and the inherent hydrogen bond cage mechanism between ammonium ions, the resultant full battery delivers a large specific energy density of 211.84Whkg-1, and it can be stably operated for 12000 cycles at 5Ag-1 for over 80 days. This explanatory understanding provides a new idea for the rational design of high-performance MOF-based ammonium ion battery cathode materials for efficient energy storage and conversion in the future.

Removal of Phosphate and Ammonium Ion from Domestic Wastewater Using Clay Feldspar in Wupa Sewage Treatment Plant Abuja

The aim of this study is centered on the sustainability of feldspar as an adsorbent as opposed to other clay minerals such as plastic clay, red clay and barite. Brauner-Emmert-Teller (BET) analysis of the clay minerals considered in this study revealed that raw feldspar had the highest surface area and pore volume of 332.8 m²/g and 0.218 cc/g respectively. Similarly, the clay minerals were used in adsorption study with feldspar producing the best removal efficiency of 90.00%and 73.96% for ammonium and phosphate ions respectively. The BET results and the adsorption test showed that feldspar was a better adsorbent than the other adsorbents. Thermal activation of feldspar was carried out at temperatures of 500–700 ◦C using muffle furnace. The BET results of the thermal activation revealed that feldspar activated at 600 ◦C has the highest surface area and pore volume of 533.9 m²/g and 0.272 cc/g respectively. The Fourier’s transformed infrared (FT-IR) results indicated that several functional groups were involved in the adsorption process of the phosphate and ammonium ions some of which were O-H, N-H and C-O groups. The results showed that irregular-layered structures of the raw feldspar became smooth and regular after thermal activation. The effects of pH, adsorbent dosage, temperature, contact time and initial PO₄3− and NH₄⁺ concentrations on the adsorption of phosphate ions and ammonium ions were investigated using atomic adsorption spectroscopy (ASS). The adsorption studies of phosphate ion and ammonium ion onto feldspar increased with contact time, adsorbent dosage and temperatures until optimum values were reached.

Impact of Pyrolysis Temperature on the Physical and Chemical Properties of Non-Modified Biochar Produced from Banana Leaves: A Case Study on Ammonium Ion Adsorption.

Given the current importance of using biochar for water treatment, it is important to study the physical-chemical properties to predict the behavior of the biochar adsorbent in contact with adsorbates. In the present research, the physical and chemical characteristics of three types of biochar derived from banana leaves were investigated, which is a poorly studied raw material and is considered an agricultural waste in some Latin American, Asian, and African countries. The characterization of non-modified biochar samples pyrolyzed at 300, 400, and 500 °C was carried out through pH, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and specific surface area measurements. The adsorption properties of banana leaf-derived biochar were evaluated by ammonium ion adsorption experiments. The results demonstrated that the pyrolysis temperature has a large impact on the yield, structure, elemental composition, and surface chemistry of the biochar. Biochar prepared at 300 °C is the most efficient for NH4+ adsorption, achieving a capacity of 7.0 mg of adsorbed NH4+ on each gram of biochar used, while biochar samples prepared at 400 and 500 °C show lower values of 6.1 and 5.6 mg/g, respectively. The Harkins-Jura isotherm model fits the experimental data best for all biochar samples, demonstrating that multilayer adsorption occurs on our biochar.

Selective adsorption of ammonium ion via cobalt-based Prussian blue analogue

Selective adsorption of ammonium ion via cobalt-based Prussian blue analogue

Adsorption of ammonium ion (NH4+) using mordenite-chitosan from synthetic and actual sewage: Batch and fixed-bed studies

The untapped NH4+ in sewage has the potential to be recovered as fertilizer via the adsorption process. While zeolite-chitosan has demonstrated better performance in nutrient recovery compared to powder zeolite, research on mordenite-chitosan remains limited. Therefore, this study focused on the mordenite-chitosan for NH4+ recovery. Based on the characterization, the physicochemical properties of mordenite-chitosan closely resemble the mordenite. The addition of chitosan has increased the adsorption capacity of mordenite by 15%. The adsorption of NH4+ on mordenite-chitosan fitted well to the Langmuir linear model with an estimated adsorption capacity of 17.7 mg/g (R2 = 0.991). The positive entropy with an enthalpy value of 44.47 kJ/mol suggests a random organization of NH4+ ions, endothermic process, and ion-exchange. Mordenite-chitosan adhered well to the Thomas model, with NH4+ adsorption capacity of 17.97 mg/g, 6.14 mg/g, and 4.84 mg/g in synthetic sewage, influent, and effluent, respectively. Factors such as the negativity of the surface mordenite-chitosan, Si/Al ratio, and framework flexibility are likely to influence the NH4+ adsorption capacity. Overall, the ion-exchange property of mordenite-chitosan emerges as the main contributor to its efficacy in NH4+ recovery.

RESEARCH AND MODELING KINETICS ION EXCHANGE INTERACTIONS

In detail, this study analysed the kinetics of ammonium ion adsorption under dynamic conditions in the "clinoptilolite -ammonium ion" system. The work includes constructing a mathematical model of this process, which allows us to estimate and predict its essential characteristics. Calculations of mass transfer coefficients revealed their dependence on the intensity of medium mixing. A significant result is that ion exchange occurs in externally diffusion and intradiffusion regions. Ion exchange rate constants were calculated for the regions of external and internal diffusion, contributing to a deeper understanding of the mechanisms of this complex process. The research results will expand our knowledge about ion exchange interactions in the " clinoptilolite -ammonium ion" system. In addition, they can be used to optimise the conditions of ammonium adsorption in similar systems, which is essential for practical applications related to water purification and other media from ammonium ions.

In situ construction of a static-dynamic hybrid interface toward stable Zn anodes for aqueous Zn-ion batteries.

Aqueous Zn-ion batteries are promising candidates for next-generation energy storage devices due to the advantages of high safety, low cost and good environmental friendliness. However, the uncontrollable dendrite growth and undesirable side reactions occurring on the Zn anode result in poor cycling stability. Herein, a Lewis base, triethanolamine, is used as the electrolyte additive to construct a hybrid solid-electrolyte interphase layer composed of a static ZnSO4·3Zn(OH)2·4H2O layer and dynamic quaternary ammonium ion adsorption layer. The static SEI layer acts as a physical barrier between the Zn anode and electrolyte, thus effectively suppressing chemical corrosion and the hydrogen evolution reaction. The dynamic layer can not only regulate the ion flux at the interface, but also promote the de-solvation of solvated Zn2+, thus leading to homogenous Zn deposition along the (002) electro-crystallization orientation. As a result, the Zn anode demonstrates an extended cycle life of 2500 h at a current density of 1.0 mA cm-2, with an areal capacity of 1.0 mA h cm-2 and a high coulombic efficiency (CE) of 98.94%. The Zn‖V2O5 cells exhibit a specific capacity of 178.4 mA h g-1 after 500 cycles, indicating both high capacity and robust cycling stability, which are essential for practical applications.

Environmental risk of ion-absorbed rare earth ores: concentration of leaching agent and fractionation of Pb.

Rare earth (RE) is an important strategic resource; however, there has been a growing concern about the environmental problems caused by RE mining, such as ammonia nitrogen pollution and heavy metal pollution. There is a limited research about the behavior of leaching agents and the fractionation of RE and heavy metal during the mining process for ion adsorption of rare earth ore (IRE-ore) in the previously available papers. In this study, (NH4)2SO4 solution, which commonly used in the production of mining IRE-ore, was used as a leaching agent. The adsorption behavior of ore soils on ammonium ions was explored by batch experiments. The adsorption process of IRE-ore on ammonium ions followed a pseudo-second-order equation and was controlled by the kinetics of surface adsorption and intra-particle diffusion; the ammonium ion adsorption isotherm conformed to the Freundlich isotherm equilibrium equation, and the higher concentration advantage made the ore soils possess a higher adsorption capacity of ammonium ion. In addition, the fractionation characteristics of lanthanum (La), cerium (Ce), and lead (Pb) in the ore soil during the leaching process were simulated based on the batch and column leaching experiments. The results demonstrated that the exchangeable states of La and Ce in IRE-ore were high, and the exchangeable, carbonate-bound La and Ce were almost all leached out by (NH4)2SO4 leaching agent, while the most of exchangeable Pb flowed out along with leaching agent, and a small amount of leached Pb in the ore soil was converted to iron and manganese oxide-bound Pb and enriched in the direction of migration of the leaching solution, and when the environment (e.g., pH and Eh) changed, this part of Pb may be re-activated. Our research might serve as crucial baseline knowledge for the adsorption of ammonium ions by ore soils, and provide a data reference for reducing the use of leaching agents and developing sustainable technologies for green mining of ion-adsorption RE ores.

Modification of crystal growth of NaA zeolite with steric hindrance agents for removing ammonium ion from aqueous solution

The incorporation of steric effects into the hydrothermal synthesis system of NaA zeolite proves to be an effective method for modifying grain size, enhancing grain dispersion and obtaining single crystal products. In this study, three different molecular configurations, namely short-chain ethanolamine (MEA), long-chain polyethylene glycol (PEG), and ring-chain cyclohexanol (CyOH), were employed to investigate the impact of steric effects on the crystal growth of NaA zeolite. The crystal form, morphology, and particle size of NaA zeolite were characterized using XRD, FT-IR, and SEM techniques. The order of steric hindrance in terms of molecular configuration was found to be as follows: CyOH > PEG > MEA. NaA-CyOH exhibited a high dispersion of single crystal particles, the smallest grain size, and the largest specific surface area and pore volume. To evaluate the ammonium ion adsorption performance, NaA-CyOH-31, the zeolite with the best performance, was utilized for studying the reaction kinetics. The results indicated that the adsorption behavior of NaA zeolite towards ammonium ion could be better described by the quasi second-order equation and the Langmuir model. Furthermore, the evaluation of the regeneration ability of NaA-CyOH zeolite demonstrated that the recovered adsorbent still maintained a high level of adsorption performance.

Crossover, volatilization, and adsorption of ammonium ions in a proton-exchange membrane electrolyzer in relation to electrochemical ammonia production

Electrochemical ammonia (NH3) production from dinitrogen (N2) could be an environmentally sustainable alternative to the traditional manufacturing process (Haber-Bosch). However, a flow electrolysis cell that could elevate the ammonia production to a scale of practical relevance has not been demonstrated yet for this emerging technology. Besides N2, NH3 can be electrochemically produced from nitrogen-containing compounds such as nitrogen oxides (NOx), nitrite (NO2–), and nitrate (NO3–). Product crossover in those processes could significantly interfere with accurate performance evaluation, which has received limited attention. Herein, the commonly used Nafion N112 membrane was found ineffective at preventing the undesired crossover of NH3 or ammonium (NH4+) ions in a flow cell even at the 1 ppm concentration level, with a normalized flux as high as 247 µmol m-2h−1 in Na2SO4 at −0.1 mA cm−2. Severe NH4+ adsorption in Nafion was also observed, particularly when no supporting electrolyte is present. Moreover, the interactions between Nafion and NH4+ depend on the supporting electrolyte type, pH changes induced by ion exchange and applied current during continuous electrolysis. Increasing the membrane thickness altered the rate of NH4+ losses, however, the NH4+ crossover and volatilization cannot be fully mitigated. Lastly, the cation exchange between membrane-adsorbed NH4+ and Na+ from the electrolyte is proposed as a membrane-cleaning procedure to reduce false positives in electrochemical NH3/NH4+ production studies.

Ultrasonic-assisted chemical modification of a natural clinoptilolite zeolite: Enhanced ammonium adsorption rate and resistance to disturbing ions

A natural clinoptilolite zeolite was modified by ultrasonic-assisted chemicals (NaOH, FeCl3 and HCl) to improve their performance in ammonium removal from (waste) water. The obtained modified zeolites were characterized by Field Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD) and gas sorption techniques to understand the relation between physiochemical factors of the modified zeolites and ammonium adsorption. The highest elimination efficiency of ammonium by the natural zeolite modified by ultrasonic-assisted HCl treatment, HZU2, was ≥ 99%. However, ammonium removal by the raw natural zeolite was only 51.66%. The efficiencies of ammonium removal in the presence of various disturbing anions and cations by the HZU2 and raw zeolite were in the range of 79–93% and 15–30%, respectively. The HZU2 was reused five times presenting stable adsorption removal of ammonium. The theoretical calculations were performed to identify the key kinetics and thermodynamics parameters controlling the adsorption rate. The maximum adsorption capacity (qmax) of HZU2 obtained by the Langmuir model was about 142.85 (mg-ammonium/g-adsorbent) suggesting that the adsorption capacity of a monolayer and the relative content of alkali metal cations are suitable for the improvement of ammonium ion adsorption. The obtained thermodynamics parameters showed that the ammonium adsorption is a spontaneous and exothermic physisorption process. Consequently, we showed that ultrasonic-assisted chemical modification is a promising approach to control both textural properties and chemical composition of natural zeolites to enhance the ammonium removal from wastewater.

Adsorption of Ammonium Ions and Phosphates on Natural and Modified Clinoptilolite: Isotherm and Breakthrough Curve Measurements

The research focuses on ammonia and phosphate removal from wastewater by using a novel metal and microwave-treated clinoptilolite. For increasing adsorption capacity, the samples were calcinated or microwave irradiated in the solutions of Fe(III), Cu (II), or Ca(II) chlorides. BET-specific surface area measurement revealed that the calcination led to a decrease from 18.254 to 11.658 m2/g. The adsorption results were fitted to theoretical models. The PO43− adsorption in all samples as well as NH4+ adsorption in natural and Fe- and Ca-modified samples is best described using the Langmuir–Freundlich model, but in calcinated and Cu-modified clinoptilolite the NH4+ sorption is better characterized by the Freundlich model. The PO43− adsorption in natural and all modified samples is best described using the Langmuir–Freundlich model. Fe-modified and calcinated clinoptilolite showed the highest NH4+ adsorption capacity of 4.375 and 2.879 mg/g. Ca-modified samples demonstrated the lowest adsorption capacity of 0.875 mg NH4+/g. The metal-modified samples exhibit a significantly higher phosphate sorption capacity (from 800.62 for Cu-sample to 813.14 mg/g for the Fe-modified sample) than natural (280.86 mg/g) or calcinated samples (713.568 mg/g). Experimental studies in dynamic conditions revealed high NH4+ and sufficient PO43− ions captured on modified clinoptilolite. This study provides a feasible approach for the synchronous removal of the main eutrophication agents for implementation in additional (tertiary) wastewater treatment facilities.

Adsorption and quantitative fluorescence-based measurement of ammonium ions using a chitosan-based hydrogel combined with p-hydroxybenzoic acid

Ammonium removal in high-density fish cultures is highly reliant on time-consuming and costly biological treatment methods. Therefore, the development of cheap and rapid chemical methods has recently garnered increasing attention. Our study developed a dissolved ammonium removal method using a chitosan-based hydrogel (Cht-HG) modified with 0.3 mM of p-hydroxybenzoic acid (Cht-0.3PHBA-HG). Our proposed method enabled the adsorption and measurement of dissolved ammonium via fluorescence detection. In the ammonium adsorption test, the maximum adsorption capacities (qm) of Cht-HG and Cht-0.3PHBA-HG were 11.6 mg g−1 and 19.9 mg g−1, respectively. Cht-0.3PHBA-HG exhibited a relatively elevated adsorption capacity (i.e., 1.71-fold higher adsorption efficiency) due to the morphological and chemical modifications attributed to p-hydroxybenzoic acid (PHBA). These findings were confirmed by our chemical characterization and adsorption test results. Particularly, the adsorbed ammonium atomic percentages (at.%) of Cht-HG-NH4 and Cht-0.3PHBA-HG-NH4 were 6.33 % and 15.2 %, respectively. Compared to Cht-HG, the adsorption properties of Cht-0.3PHBA-HG were more stable in a pH range of 2–8. Moreover, we quantitatively analyzed the oxidation of the combined PHBA at different dissolved ammonium concentrations (0.1–5.0 mM) using fluorescence detection. The fluorescence sensitivity of ammonium was maintained, even in high concentrations of common electrolytes (Ca2+, K+, Mg2+, Na+, and PO43-). The ammonium adsorption mechanisms of Cht-0.3PHBA-HG were strongly consistent with the pseudo-first order (PFO), pseudo-second order (PSO), and Langmuir models. In addition to its role as an adsorbent, Cht-0.3PHBA-HG could also be used to detect ammonium in real time.

Zeolite Composite Materials from Fly Ash: An Assessment of Physicochemical and Adsorption Properties

Waste fly ash, with both low (with the addition of vermiculite) and high contents of unburned coal, were subjected to hydrothermal syntheses aiming to obtain zeolite composite materials-zeolite + vermiculite (NaX-Ver) and zeolite + unburned carbon (NaX-C). The composites were compared with parent zeolite obtained from waste fly ash with a low content of unburned carbon (NaX-FA). In this study, the physicochemical characteristics of the obtained materials were evaluated. The potential application of the investigated zeolites for the adsorption of ammonium ions from aqueous solutions was determined. Composite NaX-Ver and parent zeolite NaX-FA were characterized by comparable adsorption capacities toward ammonium ions of 38.46 and 40.00 mg (NH4+) g-1, respectively. The nearly 2-fold lower adsorption capacity of composite NaX-C (21.05 mg (NH4+) g-1) was probably a result of the lower availability of ion exchange sites within the material. Adsorbents were also regenerated using 1 M NaCl solution at a pH of 10 and subjected to 3 cycles of adsorption-desorption experiments, which proved only a small reduction in adsorption properties. This study follows the current trend of waste utilization (fly ash) and the removal of pollutants from aqueous solutions with respect to their reuse, which remains in line with the goals of the circular economy.

An ion-selective chemiresistive platform as demonstrated for the detection of nitrogen species in water.

The use of ion-selective electrodes (ISE) is a well-established technique for the detection of ions in aqueous solutions but requires the use of a reference electrode. Here, we introduce a platform of ion-selective chemiresistors for the detection of nitrogen species in water as an alternative method without the need for reference electrodes. Chemiresistors have a sensitive surface that is prone to damage during operation in aqueous solutions. By applying a layer of ion-selective membrane to the surface of the chemiresistive device, the surface becomes protected and highly selective. We demonstrate both anion-selective (NO3-, NO2-) and cation-selective (NH4+) membranes. The nitrate sensors are able to measure nitrate ions in a range of 2.2-220 ppm with a detection limit of 0.3 ppm. The nitrite sensors respond between 67 ppb and 67 ppm of nitrite ions (64 ppb detection limit). The ammonium sensors can measure ammonium concentrations in a wide range from 10 ppb to 100 ppm (0.5 ppb detection limit). The fast responses to nitrate and nitrite are due to a mechanism involving electrostatic gating repulsion between negative charge carriers of the film and anions while ammonium detection arises from two mechanisms based on electrostatic gating repulsion and adsorption of ammonium ions at the surface of the p-doped chemiresistive film. The adsorption phenomenon slows down the recovery time of the ammonium sensor. This sensor design is a new platform to continuously monitor ions in industrial, domestic, and environmental water resources by robust chemiresistive devices.

Enhanced ammonium removal from aquatic systems by a novel copolymer

Abstract A novel copolymer was used as an adsorbent for enhanced ammonium removal in an aqueous system; different ratios of styrene–acrylic acid copolymers were synthesized by random free radical polymerization and followed by a sulfonation of styrene (acrylic acid 25%–sulfonated styrene 75%) copolymer [P(AA25/SS75)] attained the highest ammonium adsorption capacity (55.8 mg/g) due to the electrostatic attraction between positively charged NH4+ and negatively charged –COO− and –SO3- groups. FTIR spectra for sulfonated polymers illustrated the appearance of characteristic peaks at 100–1200 cm−1 indicating that the copolymers were successfully sulfonated. The influence of different experimental factors (i.e., contact time, pH, NH4+ concentration, adsorbent dose) on ammonium ion adsorption was investigated; three adsorption isotherm models including Langmuir, Freundlich, and Temkin were used to study the adsorption mechanism. The results indicated that the equilibrium of adsorption can be reached within 30 min; the highest adsorption capacity can be achieved around pH 7. Furthermore, Freundlich isotherm was the most suitable for fitting the experimental data which might expose the heterogeneity of the adsorbent surface. The regeneration and reusability studies were also implemented, and results showed that P(AA25/PSS75) was stable and regenerable using (1 M) sulfuric acid as a desorbing agent over five cycles.

Column Adsorption Studies for the Removal of Ammonium Using Na-Zeolite-Based Geopolymers

The aim of this study was to examine the removal of ammonium ions from a synthetic model solution by using Na-zeolite-based geopolymers. Na-zeolite (=analcime) is a residue from mining industry. Three adsorbents were prepared from Na-zeolite using different production steps and metakaolin as a blending agent. These novel adsorbents were investigated in a fixed-bed column system where the effects of different flow rates with the initial ammonium concentration of 40 mg/L were studied. The Thomas, Bohart–Adams and Yoon–Nelson breakthrough curve models fitted well with the experimental data with a high R2 value. After adsorption experiments, adsorbents were regenerated using a mixture of 0.2 M NaCl and 0.1 M NaOH as a regeneration agent; after that, adsorbents were reutilised for ammonium ion adsorption for three adsorption–regeneration cycles. The results of the experiment indicate that all the prepared analcime-based geopolymers are suitable adsorbents for the removal of ammonium ions and that capacity remains nearly constant for two of them during two adsorption–regeneration cycles.

Banana Peel Powder as an Effective Multilayer Adsorbent of Ammonium Ions

The recovery of ammonium ions or ammonia from wastewater using bioadsorbents offers an attractive sustainable route to nitrogen reuse and environmental remediation. In this work, we have studied the ability of banana peel powder (BNPP) for adsorption of ammonium ions. The prepared BNPP was characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. Structural and morphological features of BNPP were connected to the observed NH4+ adsorption. The adsorption kinetics was found to fulfil pseudo-first-order and pseudo-second-order models while adsorption isotherms were fit adequately by Langmuir and Freundlich models. Accordingly, the adsorption of NH4+ on BNPP is predominantly controlled by physical adsorption that enables chemisorption in a time-bound manner. The maximum adsorption capacity of BNPP was 34.48 mg/g and is superior to several prominent biomass candidates that have been reported for adsorption of NH4+. BNPP was also deployed on artificial urine, and the results suggest that it is an attractive bioadsorbent for harvesting nitrogen from liquid waste.