Adsorption Capacity Of Clinoptilolite Research Articles

Natural Zeolite Clinoptilolite Application in Wastewater Treatment: Methylene Blue, Zinc and Cadmium Abatement Tests and Kinetic Studies.

In recent decades, several abatement techniques have been proposed for organic dyes and metal cations. In this scenario, adsorption is the most known and studied. Clinoptilolite was considered, since it is a zeolite with a relatively low cost (200-600 $ tons-1) compared to the most well-known adsorbent used in wastewater treatment. In this work, Clinoptilolite was used for the adsorption of Methylene Blue (MB) at three different concentrations, namely, 100, 200, and 250 ppm. Furthermore, the adsorption capacity of the natural zeolite was compared with that of Activated Charcoal (250 ppm of MB). The two adsorbents were characterized by complementary techniques, such as N2 physisorption at -196 °C, X-ray diffraction, and field emission scanning electron microscopy. During the adsorption tests, Clinoptilolite exhibited the best adsorption capacities at 100 ppm: the abatement reached 98% (t = 15 min). Both Clinoptilolite and Activated Charcoal, at 250 ppm, exhibited the same adsorption capacities, namely, 96%. Finally, at 250 ppm MB, the adsorption capacity of Clinoptilolite was analyzed with the copresence of Zn2+ and Cd2+ (10 ppm), and the adsorption capacities were compared with those of Activated Charcoal. The results showed that both adsorbents achieved 100% MB abatement (t = 40 min). However, cation adsorption reached a plateau after 120 min (Zn2+ = 86% and 57%; Cd2+ = 53% and 50%, for Activated Charcoal and Clinoptilolite, respectively) due to the preferential adsorption of MB molecules. Furthermore, kinetic studies were performed to fully investigate the adsorption mechanism. It was evidenced that the pseudo-second-order kinetic model is effective in describing the adsorption mechanism of both adsorbents, highlighting the chemical interaction between the adsorbent and adsorbate.

INTERACTION OF PHENYLALANINE AND HISTIDINE ON EQUILIBRIUM CHARACTERISTICS OF ADSORPTION OF AMINO ACIDS ON CLINOPTILOLITE

Parameters of the equilibrium sorption of phenylalanine and histidine on clinoptilolite from aqueous solutions containing the individual amino acids and their mixtures were presented. The contribution of exchange and non-exchange components in the adsorption capacity of clinoptilolite was determined. It was found that the interfacial distribution of amino acids is determined by the ratio of CHis / CPhe and manifested in sorption equilibrium characteristics. The maximum degree of extraction of histidine is achieved at the ratio of CHis / CPhe equals to 1: 3.

Clinoptilolite-based mixed matrix membranes for the selective recovery of potassium and ammonium

A clinoptilolite-based mixed matrix membrane (MMM) was developed and studied for the selective recovery of ammonium and potassium. Adsorption of sodium (Na+), potassium (K+) and ammonium (NH4+) was investigated with single salt and equimolar salt solution under static and dynamic conditions. Furthermore, the adsorption capacity of clinoptilolite was investigated when embedded in the MMM and in clay form. Two conditioning methods were compared: HCl and NaCl. Conditioned clinoptilolite with NaCl gave higher static adsorption capacities than with HCl which alters the chemical structure of clinoptilolite. The adsorption of Na+ was not detected in the static adsorption experiments and results showed that Na+ adsorbed during the conditioning process it was exchanged by K+ and NH4+.The clinoptilolite embedded in MMM reduced the porosity of the MMM so the highest adsorption capacity was reached when the amount of polymer was the lowest: 30 wt% polymer and 70 wt% clinoptilolite. The application of MMM in a dead-end filtration cell (dynamic adsorption) resulted in higher adsorption capacities compared to static conditions and comparable results between synthetic solutions and diluted urine samples. This indicates that MMM is a suitable method for the recovery of K+ and NH4+ directly from a diluted urine matrix. The desorption (recovery) of K+ and NH4+ from MMM was higher using water at 60 °C than using an acidic treatment.

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.

Effects of Formic Acid on the Adsorption ofEscherichia ColiK88on Modified Clinoptilolite

Adsorption of Escherichia coli K88 on natural and acid-modified clinoptilolite was studied under ambient conditions. The materials under study were characterized in terms of surface area and cation-exchange capacity (CEC). Our study results indicate that treatment with formic acid can increase the Brunauer-Emmett-Teller (BET) surface area, CEC and adsorption capacity of clinoptilolite. The maximum adsorption on these non-metallic minerals was 25 mg/ml, beyond which the adsorption decreased as the amount of adsorptive increased. Time-dependent studies showed that the adsorption process reached equilibrium after 2 hours. The adsorption on E. coli K88 increased with increasing concentration of the adsorption agent as well as with increasing concentration of the bacteria in suspension. The desorption of H+ was studied by washing with a sterile physiological saline solution for 2 hours. The adsorption-desorption hysteresis suggests that the desorption rate of acid-modified clinoptilolite was much lower than th...

Improving Saline–Sodic Coalbed Natural Gas Water Quality Using Natural Zeolites

Management of saline-sodic water from the coalbed natural gas (CBNG) industry in the Powder River Basin (PRB) of Wyoming and Montana is a major environmental challenge. Clinoptilolie zeolites mined in Nevada, California, and New Mexico were evaluated for their potential to remove sodium (Na+) from CBNG waters. Based on the exchangeable cation composition, naturally occurring calcium (Ca2+)-rich zeolites from New Mexico were selected for further evaluation. Batch adsorption experiments were conducted to evaluate the potential of the Ca(2+)-rich natural clinoptilolites to remove Na+ from saline-sodic CBNG waters. Batch adsorption experiments indicated that Na+ adsorption capacity ofclinoptilolite ranged from 4.3 (4 x 6 mesh) to 7.98 g kg(-1) (14 x 40 mesh). Among the different adsorption isotherms investigated, the Freundlich Model fitted the data best for smaller-sized (6 x 8, 6 x 14, and 14 x 40 mesh) zeolites. Passing the CBNG water through Ca(2+)-rich zeolite columns reduced the salt content (electrical conductivity [EC]) by 72% with a concurrent reduction in sodium adsorption 10 mmol 1/2 L(-1/2). Zeolite technology appears to be an effective water treatment alternative to industrial membrane treatment for removing Na+ from poor-quality CBNG waters.

Adsorption of wastewater components by natural sorbents

Sorptive properties of the natural zeolite from the Sokyrnytsia Deposit have been investigated with respect to the pollution components of wastewaters from meat-processing plants, namely, ammonium nitrogen, phosphates, and protein, the concentrations of which are subject to standards. Equilibrium values of the adsorption capacity were determined and appropriate sorption isotherms were built for temperature 20°C. It was shown that the adsorption capacity of clinoptilolite with respect to one-component systems was higher as compared with the case of simultaneous adsorption of two and three components from the solution. The linear relationships of the adsorption isotherms for one-, two-, and three-component systems have been also proposed.

Ammonia Removal from Aqueous Solutions by Iranian Natural Zeolite

The capability of Iranian natural clinoptilolite for ammonia removal from aqueous solutions has been thoroughly studied. Both batch and continuous (column) experiments were carried out. The viability of this natural zeolite in reducing the leakage of ammonia to the environment through waste water streams was a main focus of this research. Through the batch experiments, the effect of process variables such as the size of zeolite particles, pH, and ammonia concentration of the feed solution on the kinetics of ammonia uptake were investigated. Ammonia removal occurred rapidly and within the first 15 minutes of contact time, a major part of ammonia was removed from the solution. An adsorption capacity about 17.8 mg NH4 +/g zeolite at feed ammonia concentration of 50 mg/L was obtained and the optimum range for pH was achieved about 5.5–7.6. The adsorption capacity of clinoptilolite in the continuous mode was about 15.16 and 15.36 mg NH4 +/g zeolite for the original and regenerated types of clinoptilolite, respectively, where feed ammonium concentration was 50 mg/L. Increasing the feed ammonium concentration to 100 mg/L did not reduce the capability of the column for its ammonium removal and up to a bed volume (BV) of 85, there was only less than 1 mg/L ammonium in the column outlet. Presence of cations such as Ca2+, Mg2+ and Na+ in the feed solution reduced the clinoptilolite adsorption capacity to about 11.68 mg NH4 +/g zeolite. Regeneration experiments were carried out using concentrated sodium chloride solutions, as well as tap water. Where tap water was used as the regenerant, gradual release of ammonium from exhausted clinoptilolite was observed.