Abstract
Nano-porous silicon (NPS) powder synthesis is performed by means of a combination of the ultra-sonication technique and the alkali chemical etching process, starting with a commercial silicon powder. Various characterization techniques {X-ray powder diffraction, transmission electron microscopy, Fourier Transform Infrared spectrum, and positron annihilation lifetime spectroscopy} are used for the description of the product’s properties. The NPS product is a new environmentally friendly material used as an adsorbent agent for the acidic azo-dye, Congo red dye. The structural and free volume changes in NPS powder are probed using positron annihilation lifetime (PALS) and positron annihilation Doppler broadening (PADB) techniques. In addition, the mean free volume (VF), as well as fractional free volume (Fv), are also studied via the PALS results. Additionally, the PADB provides a clear relationship between the core and valence electrons changes, and, in addition, the number of defect types present in the synthesized samples. The most effective parameter that affects the dye removal process is the contact time value; the best time for dye removal is 5 min. Additionally, the best value of the CR adsorption capacity by NPS powder is 2665.3 mg/g at 100 mg/L as the initial CR concentration, with an adsorption time of 30 min, without no impact from temperature and pH. So, 5 min is the enough time for the elimination of 82.12% of the 30 mg/L initial concentration of CR. This study expresses the new discovery of a cheap and safe material, in addition to being environmentally friendly, without resorting to any chemical additives or heat treatments.
Highlights
The major threat, for the time being, which must be dealt with on a global level is toxic and carcinogenic environmental pollutants
We report the application of the PALS for tracking the free volume size changes for synthesized Nano-porous silicon (NPS) powder via a combination of the alkali chemical etching process and the ultra-sonication technique, starting with commercial silicon powder
The wastewater was synthesized by dissolving the acidic Congo red dye in distilled water to gain the required waste solution concentrations; this was applied to monitor the efficiency of the NPS product’s adsorption
Summary
The major threat, for the time being, which must be dealt with on a global level is toxic and carcinogenic environmental pollutants. The ultra-sonication technique is one of the most famous materials processing techniques that is widely used for powder technology, as a result of its simplicity and effectiveness, as shown in previous research [10]. In the case of porous materials, the formation of positrons are implanted from a radioactive source in the molecular solids, and each pore of them annihilates with e- of the material’s atoms and for the formation of a positronium (Ps), s shown in previous studies. The S-parameter is defined as the ratio of counts in the central part of the Doppler broadened spectrum to the area below the annihilation line completely It depends on the average density of volume defects, which is open. This work is targeted at studying acidic Congo red dye removal from aqueous solutions using synthesized NPS powder via the adsorption process
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