Abstract
Diatomite was slightly modified with a sodium hydroxide solution. The resulting material was characterized by using energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and nitrogen adsorption-desorption isotherms. The so-treated diatomite has a high specific surface area (77.8 m2/g) and a high concentration of isolated silanol groups on the surface, and therefore, its adsorption capacity increases drastically in both the single and binary adsorption systems for rhodamine B and methylene blue. The binary system is more effective than the single system, with methylene blue being adsorbed more than rhodamine B. The adsorption process is spontaneous and fits well with the Langmuir isothermal model, and it depends on pH significantly.
Highlights
Dyes are widely used in numerous applications, such as textile, paper, plastic, and dye industries [1]
Methylene blue (Guangdong, China) and rhodamine B (HiMedia, India) dyes were used as adsorbates
O and Si content than purified diatomite, and this is probably due to the removal of organic constituents and the dissolution of SiO2 during alkali treatment
Summary
Dyes are widely used in numerous applications, such as textile, paper, plastic, and dye industries [1]. The amount of dyes produced annually worldwide is estimated at over 7 × 105 tons, and more than 100,000 commercially available dyes with different physical and chemical properties are being used [2,3,4]. Various dyes and their decomposition products are toxic and carcinogenic, posing a danger to aquatic organisms [1, 5]. Chemical oxidation has been extensively studied for dye removal from wastewaters [1, 7,8,9]. The adsorption technique has proven to be a simple, efficient, and attractive way to remove nonbiodegradable pollutants (including dyes) from wastewaters [5, 10, 11]
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