Hydro-Adsorption Study by Dynamic Laser Speckle of Natural Zeolite for Adsorbent and Fertilizer Applications

Abstract

The dynamic behavior caused by hydro-adsorption process of materials based on a rich mineral clinoptilolite together with their acidic, basic and calcinated forms has been studied by the dynamic laser speckle (DLS) technique. We propose a modified Peleg's equation to improve fitting of DLS data. Textural (BET), structural (XRD) and spectroscopic (FTIR) properties were also studied and compared. We demonstrated that DLS was the most sensitive, simple and inexpensive method for comparing the performance of adsorptive materials with slightly modified surfaces. It also allowed the correlation with physicochemical properties.

Dynamic laser speckle technique as an alternative tool to determine hygroscopic capacity and specific surface area of microporous zeolites

“…The natural sample was modified by 1M solutions of ammonium hydroxide and nitric acid and they were also thermally treated at 250 • C (523.15 K) and 500 • C (773.15 K). For more details see [9]. Surface areas and porosity of samples were determined by physical N 2 adsorption at 77 K (BET model) using a Micromeritics apparatus ASAP 2010.…”

“…where M ij is the number of the gray-level i followed by the gray level j in the horizontal direction of the THSP matrix. For more details of this method see References [9] and [29].…”

“…When an AS is "activated" by a thermal treatment, an dehydration process occurs and they acquire a great adsorption capacity. Additionally, the treatment with concentrated acids or bases also modifies their hygroscopic properties as previously reported [7][8][9]. Furthermore is renowned that hydrogen bonding interactions and electrostatic attraction forces on the surface of AS modified with anionic and/or cationic species has a significant effect on different industrial application [3,4].…”

“…Furthermore, as previously reported in Reference [9], Hawkes and Flink, Peleg and Azuara models can be also used [40][41][42][43][44][45][46][47][48][49][50]. Application of all these models to the DLS experimental data resulted in a not good fit.…”

“…This simple and relatively inexpensive technique can be also used for the hygroscopic characterization of different materials. We have previously reported the hygroscopic study of the zeolites modified with acid, base and temperature treatment by using the dynamic laser speckle technique [9]. In view of the foregoing results obtained by the DLS as a characterization technique for zeolites, we herein report a useful and alternative method for the specific surface area determination…”