Adsorption Capacity Of Natural Zeolite Research Articles

Fixed-bed adsorption of methylene blue using granular NaX zeolite/attapulgite composite: efficiency, mechanism and reusability of saturated G-NaX/A

A novel granular NaX zeolite/attapulgite (G-NaX/A) composite was developed to address the challenges of high pressure drop in fixed beds with powder synthetic zeolite and low adsorption capacity of natural zeolite. The synthesized G-NaX/A retains the micropores of NaX and the mesoporous of attapulgite. The BET specific surface area reached 481.17 m2/g, and the total pore volume was 0.3549 cm3/g. The G-NaX/A maximum methylene blue (MB) adsorption capacity was 1.56 times that of commercial granular activated carbon (7.41 mg/g). The breakthrough time and adsorption capacity improved with lower influent flow rate and MB concentration and higher pH. Under optimal conditions (flow rate: 150 mL/min, MB concentration: 25 mg/L, pH = 8), it achieved a maximum adsorption capacity of 11.51 mg/g and a breakthrough time of 2.54 h. The adsorption behavior of G-NaX/A was well-fitted by the Yoon–Nelson and Thomas models at different operating conditions. The mechanism studies revealed that MB (cation: C16H18SN3+) removal by G-NaX/A occurred through electrostatic attraction, ion exchange with Na+/Mg2+, surface coordination with ≡Al/SiOH, and surface physical adsorption. The regeneration studies confirmed the reusability potential of G-NaX/A by calcining at 500 °C for 2 h, and significantly improved adsorption capacity reaching about 14.39 mg/g, 16.31 mg/g and 14.07 mg/g across the three adsorption-regeneration cycles respectively. The findings support G-NaX/A technical feasibility, high adsorption capacity and potential for further scaling in fixed bed adsorption studies.

FLUORIDE IONS REMOVAL EFFICIENCY OF NATURAL/ACTIVATED ZEOLITE AND BENTONITE SORBENTS

Addressing the health concern of fluoride ions contamination in water, that cause such deceases as dental and skeletal fluorosis, requires the development of effective adsorption materials for water treatment. Our research objective was to evaluate the adsorption properties and capacities of zeolite and bentonite, sourced from Ukrainian deposits, and their acid-activated forms in relation to fluoride ions and estimate fitting this data to various adsorption models. Characterization of natural and acid-activated zeolite and bentonite sorbents was performed through X-ray diffraction to determine the phase composition of these substances. Adsorption experiments were carried out at different initial fluoride ions concentrations (3, 5, 10 and 15 mg/l) and pH (3.7; 7.5). Acidification (changing pH from 7.5 to 3.7) increase adsorption capacity of natural zeolite and bentonite more than twice. It was found that natural zeolite removes fluoride ions at the level of 67 % at pH 3.7 and a high dosage of sorbent – 10 g/l and an initial concentration of fluoride ions – 5 mg/l, while its acid‑activated form was more effective - the removal of fluoride ions is 86 % at a lower dosage of sorbent – 1 g/l. Similarly, natural bentonite demonstrated a maximum removal efficiency of 45 % at pH 3.7 and a dosage of sorbent – 10 g/l, and its acid-activated form allowed for the removal of fluoride ions of about 83 % at a dosage of sorbent – 2 g/l at the same fluoride ions concentration. It is shown that the Vagelar-Langmuir (VL) isotherm model is the most accurate for describing the process of fluoride ions adsorption by acid-activated forms of natural sorbents, where the R² values are close to 0.999, indicating monolayer adsorption on homogeneous active centers. The obtained results indicate the greater efficiency of acid-activated forms of natural sorbents and the prospects of their use for the removal of fluoride ions from water.

PHYSICOCHEMICAL CHARACTERISTICS AND CARBON DIOXIDE SORPTION PROPERTIES OF NATURAL ZEOLITES

The physicochemical characteristics of natural zeolites from the Tayzhuzgen and Shankanay deposits have been studied by BET, SEM, XRD, and FT-IR spectroscopy. Sorption properties of natural zeolites for carbon dioxide were studied in the flow mode in the temperature range of 50-300 °C. Among the studied samples, the most active in the process of capturing CO2 was the natural zeolite of the Tayzhuzgen deposit, at a temperature of 300 °C, the adsorption capacity for carbon dioxide was 27.4%. The high CO2 adsorption capacity of natural zeolite from the Tayzhuzgen deposit is due to its specific surface area and high Si/Al ratio.

Investigation on the lead adsorption capacity of Iranian natural zeolite: modifications, structural effects, adsorption isotherms, kinetics, and mechanism studies

ABSTRACT Clinoptilolite (NZ) as a natural and cost-effective adsorbent, modified with two different methods. At the first stage, by sodium chloride solution to obtain NaCl-modified natural zeolite (NaCl-MNZ), then sodium dodecyl sulfate (SDS) was used to modify NaCl-MNZ (SDS-MNZ). Along with NZ, NaCl-MNZ, and SDS-MNZ, commercial NaY zeolite was also used for removing lead cations from synthesized wastewater. The adsorption of SDS molecules on the outer surface of zeolite was confirmed by FTIR and the specific surface area of the SDS-MNZ was decreased due to the coverage of smaller pores by anionic surfactant molecules. The zeta potential measurements also revealed that the modification process has decreased the surface charge of the zeolite significantly, which was favorable for the adsorption of Pb2+ cations and improved clinoptilolite performance. The non-linear adsorption kinetics and isotherms are best described by the pseudo-first-order and Sips model, respectively. The maximum adsorption capacity of lead ions were 25.8435, 39.5992, 38.5454, and 101.0240 (mg/g) for NZ, NaCl-MNZ and SDS-MNZ and NaY, respectively. The results indicated that the adsorption capacity of natural zeolites modified with NaCl and SDS were approximately 35% and 33% higher than that of the clinoptilolite alone.

Optimizing of Competitive Adsorption Methylene Blue and Methyl Orange using Natural Zeolite from Ende-Flores

<p>Waste from the textile industry is considered a potential source of environmental pollution, especially water, because it contains dangerous dyes. In this research, natural zeolite is an effective and efficient alternative to overcome pollution caused by methylene blue and methyl orange dyes. Activation of natural zeolite was carried out with 3 M HCl solution and was characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Simultaneously, the methylene blue and methyl orange adsorption processes were studied in variations in the weight of the adsorbent, contact time, and pH. The concentration of dyes left in the solution was observed with UV-Vis Spectrophotometer. The results showed that the adsorption capacity of natural zeolite in absorbing methylene blue was 21.189 mg / g and methyl orange was 18.208 mg / g. The optimum conditions of dyes adsorption are achieved with successive adsorbent weights 0.3 g and 0,4 g, following contact times 60 minutes and 90 minutes, and successive pH 6 and 2. The adsorbent weight factor, contact time, and pH affect the adsorption of dyes by natural zeolite from Ende.</p>

Optimasi Adsorpsi Kompetitif Pewarna Biru Metilena dan Metil Oranye Menggunakan Adsorben Zeolit Alam Ende - Nusa Tenggara Timur (NTT)

Waste from the textile industry is considered as a potential source of environmental pollution, especially water because it contains dangerous dyes. In this research, natural zeolite is used as an effective and efficient alternative adsorbent to overcome pollution caused by methylene blue and methyl orange dyes. Activation of natural zeolite was carried out with 3 M HCl solution and was characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). While the methylene blue and methyl orange adsorption processes were studied in variations in the weight of the adsorbent, contact time, and pH. The concentration of dyes left in the solution was observed with Spectrophotometer UV-Vis. The results showed that the adsorption capacity of natural zeolite in absorbing methylene blue was 21.189 mg/g and and methyl orange was 18.208 mg/g. The optimum conditions of methylene blue and methyl orange adsorption are achieved with successive adsorbent weights 0.3 g and 0,4 g, successive contact times are 60 minutes and 90 minutes, and successive pH are 6 and 2 respectively. The adsorbent weight factor, contact time, and pH have an effect on the adsorption of methylene blue and methyl orange by natural zeolite from Ende.

Removal of crystal violet dye by an efficient and low cost adsorbent: Modeling, kinetic, equilibrium and thermodynamic studies

Natural zeolite as a low cost clay was tested for removal of crystal violet known as a noxious dye. Five characterization techniques were used for this study Optimizing and modeling of adsorption were performed at minimum time by an applicable technique named as response surface methodology (RSM). Three effective variables (pH, temperature (T) and adsorbate-to-adsorbent ratio (a/A)) were monitored to obtain the dye removal efficiencies. The maximum removal of dye was obtained at pH=10, T=25°C and a/A=0.1 g/g. For natural zeolite, the Fractal-Langmuir model was selected as an appropriate model for kinetic studies and the Freundlich isotherm was the best isotherm for equilibrium studies. Thermodynamic investigations showed that the adsorption of dye on natural zeolite is endothermic process and a spontaneous reaction. The maximum dye adsorption capacity of natural zeolite and Merck activated carbon on the surface of each adsorbent was obtained at 177.75 and 84.11 mg/g, respectively. In comparison with the maximum adsorption capacity of activated carbon obtained from Merck Company, we can conclude that natural zeolite possesses a higher adsorption capacity. These results reveal that, natural zeolite is an excellent and affordable adsorbent for removal of crystal violet from wastewater as compared to activated carbon.

Effect of alkali-treatment on the characteristics of natural zeolites with different compositions

A series of natural zeolites with different compositions were modified by post-synthesis modification with sodium hydroxide (NaOH) solution. Natural and modified zeolites were characterized by XRD, SEM, nitrogen adsorption, FTIR, zeta potential and temperature programmed desorption of ammonia (NH3-TPD). The adsorption capacities of these samples were evaluated by the adsorption of manganese from aqueous solution. The treatment with NaOH led to a decrease in the surface area and microporosity of all natural zeolites as well as partly damage of the zeolite structure depending on zeolite composition. In addition, the amount of weak, medium and strong acid sites in the zeolites was changed significantly by NaOH treatment depending on zeolite composition. The NaOH treatment resulted in a four-fold improvement in adsorption capacity of natural zeolite originated from Bigadic and a twofold decrease in that of the natural zeolite originated from Manisa-Gordes. Although the improved adsorption capacity might be mainly due to modification of porosity in the zeolites and formation of hydroxysodalite, the reduced adsorption capacity of the zeolite might be mainly due to a significant deformation of the zeolite structure. The pseudo-second-order kinetic model for the adsorption of manganese on all natural and modified zeolites fits well.

Phosphate removal using zeolite in treatment wetlands under different oxidation-reduction potentials

The aim of this study was a comparison between PO4−3-P removal from sewage using zeolite as support medium in subsurface flow treatment wetlands (SSF TWs) operated with different oxidation-reduction potentials (ORPs). In addition, the zeolite’s phosphate adsorption characteristics were evaluated. For this, Two mesocosm SSF TWs were installed and operated during 504 d for the PO4−3-P adsorption from sewage: a) mesocosm SSF TW with natural zeolite (MTW-Z1) and b) mesocosm SSF TW with gravel (MTW-G1). Two ORPs was used in MTW-Z1 and MTW-G1: a) ORP-A, ORP >+50 mV, b) ORP-B, ORP <−50 mV. Furthermore, the adsorption characteristics were evaluated in batch assays (zeolite amount and particle size were studied) with different PO4−3-P initial concentrations. Regarding the mesocosm SSF TWs evaluation, the PO4−3-P removed from sewage by MTW-Z1 is between 20% and 50% significantly (p < 0.05) higher than the MTW-G1. At the same time, ORP-A, above +50 mV, significantly improves (p < 0.05), by 10% more, the PO4−3-P removal capacity from sewage. Regarding adsorption characteristics, maximum adsorption capacity determined by Langmuir kinetic was 0.03 mg PO4−3-P g−1 for initial concentrations of 10–15 mg PO4−3-P L−1. In the case of MTW-Z1 with ORPs A (>+50 mV) and B (<−50 mV), the zeolite maximum adsorption capacity was 0.3 mg PO4−3-P g−1. Therefore, the potential maximum adsorption capacity of natural zeolite used as a medium in SSF TWs with ORP conditions below −50 mV and above +50 mV can be increased until 10-fold regarding Langmuir adsorption kinetic.

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.

Evaluation of physicochemical methods in enhancing the adsorption performance of natural zeolite as low-cost adsorbent of methylene blue dye from wastewater

The main aim of this study was to evaluate different facile and cost-effective physicochemical methods in enhancing the adsorption capacity of natural zeolite and subsequently demonstrate the removal of methylene blue (MB). Four different physicochemical methods, namely: acid treatment (AT), base treatment (BT), combined acid-thermal (ATT) and base-thermal treatments (BTT) were investigated. This was followed by understanding the impact of the physicochemical methods on the surface characteristics and properties of modified zeolite through advanced characterisations using field emission-scanning electron microscopy, Fourier-transformed infrared spectroscopy and Brunauer–Emmett–Teller specific surface area and porosity measurements. Batch adsorption studies were carried out using the modified zeolite adsorbents, in order to evaluate the highest removal efficiency of MB under varying adsorption conditions of: pH, initial MB concentration and modified zeolite loading. Results showed that both the physicochemical methods of AT (using 0.4 M HCl) and BT (using 4.0 M NaOH) are able to enhance the adsorption capacity of natural zeolite from 41% to 98.8% and 52.2%, respectively. Surprisingly, the combined physicochemical methods of ATT and BTT showed a reduction in adsorption performance when benchmarked to AT and BT alone. The adsorption data were analysed and modelled using Langmuir, Freundlich, Redlich-Peterson and Koble-Corrigan isotherm models, also the adsorption kinetics were evaluated using pseudo-first and pseudo-second order models. It was found that the adsorption data and kinetics were best represented using the Koble-Corrigan and pseudo-second order models. The improvements yielded through both the AT and BT modified zeolites were found to be promising and have the potential to be used as low-cost adsorbents for wastewater treatment.

The adsorption and mass-transfer process of cationic red X-GRL dye on natural zeolite

The adsorption behavior of natural zeolite was studied in order to determine the adsorption capacity and mass-transfer process of cationic red X-GRL (C(18)H(21)BrN(6)) onto the adsorbent. The adsorption tests to determine both the uptake capacity and the mass-transfer process at equilibrium were performed under batch conditions, which showed rapid uptake in general for the initial 5 min, corresponding to 92% total removal. The equilibrium adsorption capacity value (q(e,cal)) in pseudo-second-order kinetics was 13.51 mg/g at 293 K and the whole adsorption process was governed by physical adsorption with an endothermic, endothermic spontaneous nature. Adsorption tests indicated that the zeolite has great potential as an alternative low-cost material in the treatment of X-GRL drainage. However, the mass-transfer process to determine the rate-controlling steps showed that both film diffusion and pore diffusion were important in controlling the adsorption rate. The adsorption process was governed by film diffusion while pore diffusion was poor because the X-GRL molecules could not penetrate into the zeolite easily. The X-GRL molecules were only adsorbed on the external surface of the zeolite. Hence, to improve the adsorption capacity of natural zeolite further, modification to expand its micropores is necessary.

Modification of natural zeolite with NaOH for removal of manganese in drinking water

Natural zeolite (NZ) obtained from the Manisa-Demirci region of Turkey was modified by NaOH aqueous solutions (0.5–2.0mol/dm3) and the adsorption capacity of natural and modified forms was determined for manganese removal. The characterisations of the zeolites were carried out by XRD, N2 sorption, FTIR, NH3-TPD and SEM-EDS. Treatment of the NZ with NaOH leads to a significant decrease of its silica content by desilication and an increase of its Na content by formation of hydroxysodalite. It was seen from the NH3-TPD results that NaOH treatment alters the acidity of zeolite. While the number of weak and medium Brønsted/Lewis acid sites decreases, the number of strong acid sites increases through the introduction of Na+ and the removal of silica. Treatment with NaOH has the effect of multiply by two the manganese adsorption capacity of the natural zeolite. The maximum manganese adsorption capacity was achieved with the zeolite treated with 1.5M of NaOH. More than this concentration of NaOH leads not only to a decrease in adsorption capacity of natural zeolite for manganese, but also to a significant deformation of the zeolite structure. The Langmuir isotherm model fits well with the results obtained from manganese adsorption on natural zeolite, while the Freundlich isotherm model fits well with the results obtained on NaOH modified zeolites.

Adsorption of Xylene From Air by Natural Iranian Zeolite

Background: Aromatic organic solvents are extensively used in various industries. Xylene is a colorless, transparent liquid, with the characteristic odor of the aromatic hydrocarbons family, which is widely used in industries. Adsorption is a conventional method of purifying polluted air containing volatile organic compounds (VOCs). Zeolite has many unique properties such as high capacity, molecular sieve characteristics, nonflammability, thermal stability, and strong acid sites. Moreover, it is reconstructed at low temperatures. Objectives: In this study, we investigated the effect of various parameters on the adsorption capacity of natural zeolite (clinoptilolite) for xylene adsorption. Materials and Methods: Physical and chemical properties of natural zeolites were tested by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and elemental analyses of natural zeolites were characterized by X-ray diffraction. Xylene concentration was measured at various times through concentrations-measured valve before and after the adsorbent bed reactor by the direct reading of Phocheck (Ion Science Ltd, UK). Results: Experimental results showed that clinoptilolite is a potential sorbent for xylene in the range of ppm, and the breakthrough time would be reduced by increasing the concentration. The optimal temperature of xylene adsorption on natural zeolite was 35℃ and by increasing the temperature, the absorption efficiency of clinoptilolite was declined. The results showed that the breakthrough time and the exhaustion point time at the optimal conditions are 65 and 95 minutes, respectively. Adsorption capacity of clinoptilolite was obtained as 1.69 mg xylene/g zeolite. Conclusions: Experimental results showed that clinoptilolite is a potential sorbent for xylene in the range of ppm and the breakthrough time was reduced by increasing the concentration. Adsorption rate were increased by increasing concentration of xylene. Presence of xylene molecules in high concentration enhances their transfer and contact with adsorbent; as a result, by increasing gas concentration, breakthrough time in zeolite will be shorter.

Removal of Fe(III), Mn(II) and Zn(II) from palm oil mill effluent (POME) by natural zeolite

The adsorption capacity of natural zeolite for the removal of heavy metal ions, zinc Zn(II), manganese Mn(II) and iron Fe(III), found in palm oil mill effluent was investigated in this study. The effects of contact time, agitation speed, pH, and sorbent dosage on the sorption of heavy metals were evaluated. The desorption potential of zeolite was also investigated. The sorption was fast with equilibrium reached within 180min. The metal sorption increased with pH, and adsorption capacities ranged between 0.015 and 1.157mg/g of zeolite. Equilibrium data followed the Langmuir isotherm model while the kinetic data were well described by the pseudo-second-order model. Maximum desorption was attained by HCl with 69.638, 58.575 and 61.516% of the initial adsorbed amount for Fe, Zn and Mn, respectively. More than 50% of Zn(II) and Mn(II) and about 60% of Fe(III) could be removed in the experiments.

Removal Characteristics of Cd(II), Cu(II), Pb(II), and Zn(II) by Natural Mongolian Zeolite through Batch and Column Experiments

The removal characteristics of Cd(II), Cu(II), Pb(II), and Zn(II) from model aqueous solutions by 5 natural Mongolian zeolites were investigated. The adsorption of metals on zeolites reached a plateau value within 6 h. The adsorption kinetic data were fitted with adsorption kinetic models. The equilibrium adsorption capacity of the zeolites was measured and fitted using Langmuir and Freundlich isotherm models. The order of adsorption capacity of zeolite was Pb(II) > Zn(II) > Cu(II) > Cd(II). The maximum adsorption capacity of natural zeolite depends on its cation exchange capacity and pH. The leaching properties of metals were simulated using four leaching solutions. The results show that natural zeolite can be used as an adsorbent for metal ions from aqueous solutions or as a stabilizer for metal-contaminated soils.

Study on Modification and Phosphorus-Adsorption Capacity of Zeolite

Zeolite is a kind of normal adsorber. Unfortunately the adsorption capacity of natural zeolite is low, it must be activated on behalf of reaching a higher adsorption capacity. On this condition, removal of phosphorus through modifying zeolite has been studied in lab scale through using a mechanically stirred batch system. The results showed that the adsorption isotherm of modified zeolite conformed to Freundlich model and the rate of adsorption conformed to Banerm equation.

Adsorption properties of a natural zeolite–water pair for use in adsorption cooling cycles

The equilibrium adsorption capacity of water on a natural zeolite has been experimentally determined at different zeolite temperatures and water vapor pressures for use in an adsorption cooling system. The Dubinin–Astakhov adsorption equilibrium model is fitted to experimental data with an acceptable error limit. Separate correlations are obtained for adsorption and desorption processes as well as a single correlation to model both processes. The isosteric heat of adsorption of water on zeolite has been calculated using the Clausius–Clapeyron equation as a function of adsorption capacity. The cyclic adsorption capacity swing for different condenser, evaporator and adsorbent temperatures is compared with that for the following adsorbent–refrigerant pairs: activated carbon–methanol; silica gel–water; and, zeolite 13X–water. Experimental results show that the maximum adsorption capacity of natural zeolite is nearly 0.12 kg w /kg ad for zeolite temperatures and water vapor pressures in the range 40–150 °C and 0.87–7.38 kPa.

Utilization of bentonite-embedded zeolite as clay liner

Bentonite-embedded zeolites (BEZ) with different bentonite content were developed for possible use as barrier material, as an alternative to bentonite-embedded sand (BES). Adsorption characteristics of Na-bentonite, Ca-bentonite and natural zeolite; cation exchange capacity (CEC) of Na-bentonite and natural zeolite; volumetric shrinkage, compaction characteristics; and hydraulic conductivity of the mixtures were investigated. Adsorption isotherm and CEC results indicate that the lead (Pb) adsorption capacity of natural zeolite is almost one-third of Na-bentonite. Considering the zero adsorption capacity of sand, the practical implication of high CEC is the remarkable savings in terms of both materials used and space where the waste is disposed. Furthermore, volumetric shrinkage and compaction results reveal that the optimum moisture content of BEZ is far less than the moisture content that can create 4% volumetric shrinkage, which is the upper limit for liner materials. Hydraulic conductivity tests on BEZ with 10% and 20% bentonite content show that the hydraulic conductivity of both mixtures are less than 1×10 −9 m s −1, which meets the common regulatory requirements. Moreover, the test results reveal that variations in hydraulic conductivity of the mixtures with different stress conditions are negligible for practical purposes.