Browsing by Autor "Farid Akhtar"

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Adsorption of heavy metals on natural zeolites: A review
(Elsevier BV, 2023) Lisbania Velarde; Mohammad Sadegh Nabavi; Edwin Escalera; Marta‐Lena Antti; Farid Akhtar
Bolivian natural zeolite as a low-cost adsorbent for the adsorption of cadmium: Isotherms and kinetics
(Elsevier BV, 2024) Lisbania Velarde; Dariush Nikjoo; Edwin Escalera; Farid Akhtar
Population growth in recent years has led to increased wastewater production and pollution of water resources. This situation also heavily affects Bolivia, so wastewater treatment methods and materials suitable for Bolivian society should be explored. This study investigated the natural Bolivian Zeolite (BZ) and its NaCl-modified structure (NaBZ) as adsorbents for cadmium removal from water. The natural BZ and the modified form NaBZ were investigated by different physicochemical characterization techniques. Furthermore, XPS and FT-IR techniques were used to investigate the adsorption mechanisms. The cadmium adsorption on BZ and NaBZ was analyzed using various mathematical models, and the Langmuir model provided a better description of the experimental adsorption data with cadmium adsorption capacities of 20.2 and 25.6 mg/g for BZ and NaBZ, respectively. The adsorption followed the pseudo-second order kinetics. The effect of different parameters, such as initial cadmium concentration and pH on the adsorption was studied. In addition, the results of the regeneration test indicated that both BZ and NaBZ can be regenerated by using hydrochloric acid (HCl). Finally, the adsorption experiment of BZ and NaBZ on a real water sample (brine from Salar de Uyuni salt flat) containing a mixture of different heavy metals was carried out. The results obtained in this study demonstrate the effectiveness of natural BZ and modified NaBZ in the removal of heavy metals from wastewater.
Conversion of Glass Waste into Zeolite A Adsorbent for Efficient Ammonium Ion Adsorption from Aqueous Solution: Kinetic and Isotherm Studies
(Multidisciplinary Digital Publishing Institute, 2025) Neysa Pereyra; Urooj Kamran; Wilson Aguilar-Mamani; Farid Akhtar
In this study, a zeolitic adsorbent (AGW-ZA) was successfully developed from glass waste (GW)-derived aluminosilicates. The GW, serving as the starting material, underwent alkaline activation and hydrothermal treatment to yield the AGW-ZA adsorbent, which exhibited a surface area of 216.48 m2/g. The AGW-ZA demonstrated significantly higher ammonium (NH4+) ion adsorption (142.5 mg/g at 1000 mg/L) than pristine GW (80.0 mg/g). Optimal adsorption experimental parameters were identified (0.1 g dosage, pH = 7, and 10 h contact time) to determine the maximum NH4+ ions’ adsorption potential by adsorbents. Kinetic and isotherm models were applied to experimental data to describe the adsorption mechanisms. The pseudo-second-order model provided the best fit for both AGW-ZA and pristine GW, indicating that the adsorption process is followed by chemical interaction via ion exchange. Regarding isotherms, the Freundlich model was most suitable for AGW-ZA, signifying that NH4+ ions adsorbed on heterogeneous adsorbent surfaces by forming multilayers, while the Temkin model fit the pristine GW data, indicating the chemisorption nature with medium adsorbate–adsorbent interactions above the heterogeneous surface. This study explores the potential of transforming discarded GW into a high-performance zeolitic adsorbent for the mitigation of environmental pollution by removing NH4+ ions from wastewater while simultaneously addressing waste management challenges.
Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment
(Elsevier BV, 2018) Wilson Aguilar-Mamani; Farid Akhtar; Jonas Hedlund; Johanne Mouzon
Surfactant-Modified Bolivian Natural Zeolite for the Adsorption of Cr (VI) from Water
(Multidisciplinary Digital Publishing Institute, 2024) Lisbania Velarde; Edwin Escalera; Farid Akhtar
The present study reports the surfactant modification of Bolivian natural zeolite with hexadecyltrimethylammonium bromide (HTDMA-Br) for the adsorption of hexavalent chromium Cr (VI) anions from water. The surfactant-modified natural zeolite was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherms, and Fourier-transform infrared spectroscopy (FTIR) to analyze the effect of its modification with HTDMA-Br and to verify its charge on the zeolite surface. We report a maximum adsorption capacity of 17 mg/g of Cr (VI) anions, surpassing the findings of some of the previous investigations on surfactant-modified natural zeolites of different geological origins. The analysis of the equilibrium data described the Cr (VI) anions adsorption by Langmuir isotherm and the pseudo second-order kinetic model. In addition, thermodynamics revealed an exothermic adsorption. Furthermore, anion exchange, electrostatic attraction, and chemical reduction were indicated to be dominating sorption mechanisms by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) characterization techniques.