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This work investigated the ion exchange of ammonia on clinoptilolite obtained from mineral deposits located in San Luis Potosi and Sonora, Mexico. Experimental ion exchange isotherm data were obtained in a batch adsorber. The effects of temperature and solution pH on the ion exchange capacity were studied and it was found that the exchange capacity was slightly increased by augmenting the temperature and by decreasing the pH from 6 to 3. The ion exchange capacity was independent of the diameter of the zeolite particles. The reversibility of ion exchange was analyzed by desorbing the ammonia exchanged on the zeolite. The ion exchange was reversible when 1% NaCl solution was used as the desorbing solution, but more ammonia was desorbed using 1% KCl solution in the desorption step. It was concluded that a considerable amount of ammonia was exchanged on the clinoptilolite and that the exchange capacity was slightly dependent on the temperature and pH.

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BACKGROUND A study of copper adsorption onto biosorbents prepared from grapefruit peels (GP) is presented. The objectives of the present analysis were: (1) to evaluate the use of Instant Controlled Pressure Drop (DIC) as a treatment of biosorbents preparation; (2) to assay the modified biosorbents in fixed‐bed columns; and (3) to elucidate an adsorption mechanism of the metal on the modified biosorbents. RESULTS Mercury intrusion porosimetry studies showed that the use of DIC increases the porosity of material 11.3‐fold. Adsorption capacity of GP biosorbents indicate that those prepared using a DIC process had an increase of 32% and by using a subsequent chemical treatment, an enhancement of 69%, compared with simple dried GP peel. In fixed bed adsorption studies, the maximum adsorption capacity of the bed and the minimum adsorbent rate were 52.48 mg g−1 and 24 g L−1, respectively. CONCLUSION Based on the results from the adsorption and characterization studies performed by SEM‐EDS, FTIR and XPS, it is proposed that the adsorption mechanism was a physisorption phenomenon, between oxygen‐containing groups and Cu(II) from water. High adsorption capacity can be achieved using modified GP peels in fixed‐bed columns; therefore, it is feasible to use it as a non‐conventional adsorbent. © 2016 Society of Chemical Industry