Upgraded modified forms of bituminous coal for the removal of safranin-T dye from aqueous solution

Abstract

Natural bituminous coal was used as a precursor in the synthesis of different modified products. The modification of coal was performed by treating it with nitric acid (N-coal), coating its surface by zinc oxide nanoparticles (Z-coal), and converting it into porous graphite (PG). The effect of modification processes on the structures, morphologies, and optical properties was followed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), and UV/VIS spectrophotometer analysis. The surface of N-coal grains becomes smoother than the surface of raw coal grains due to the removal of the associated impurities and the formation of nitrogen function groups. For Z-coal, the whole surface of coal grains appears to be completely covered by agglomerated ZnO nanoparticles of massive density and irregular shapes. The average crystallite size of the formed ZnO is ~22.2 nm and density of dislocations is 2.029 × 10 dislocation/nm. Also, the removal of safranin-T dye by natural bituminous coal and its modified forms was investigated as a function of contact time, adsorbent mass, initial dye concentration, and pH value. At pH 8, the PG showed higher efficiency (96%) than Z-coal (93.5%), N-coal (74.5%), and natural coal (62%) after 2 h for 0.1 g on 100 mg/L dye. The obtained results are well fitted by pseudo-second-order kinetic than by intraparticle diffusion and Elovich kinetic models for the adsorption by N-coal, Z-coal, and PG, whereas the adsorption by raw coal is well fitted with both pseudo-second-order and Elovich kinetic models. The Langmuir isotherm model fits well the equilibrium adsorption isotherm of safranin by raw coal and its modified forms. The values of maximum adsorption capacity were calculated for raw coal, N-coal, Z-coal, and PG to be 21.3, 27.4, 32.46, and 33.67 mg/g, respectively. A monolayer model with one energy and a monolayer model with two energies as advanced equilibrium models were investigated for more physical interpretation of the adsorption process. The calculated parameters (number of adsorbed molecules per site and number of receptor sites per unit mass) reflected the role of modification processes in the adsorption behavior of safranin. Graphical abstract High volatile bituminous coal and its modified forms have been used for the removal of Safranin-T dye from aqueous solution.

Sulfonation of Natural Carbonaceous Bentonite as a Low-Cost Acidic Catalyst for Effective Transesterification of Used Sunflower Oil into Diesel; Statistical Modeling and Kinetic Properties

“…Regarding the spectrum of CB, it also shows the identification bands of the montmorillonite but at slightly deviated positions in addition to other bands related to the intercalated organic matters (Figure 3B). The identified organic chemical groups are the C−H stretching (2924.8 cm −1 ), CO stretching (1620 cm −1 ), and CH or C−OH stretching (1428 cm −1 ) 26 (Figure 3B).…”

Photocatalytic degradation and photo-Fenton oxidation of Congo red dye pollutants in water using natural chromite—response surface optimization

“…Several techniques have been investigated for dye removal from water. These methods included physical, chemical and biological methods (Shaban et al 2017c;Robinson et al 2001). The physical methods represented by adsorption, coagulation, and filtration.…”

Enhanced Adsorption of Toxic and Biologically Active Levofloxacin Residuals from Wastewater Using Clay Nanotubes as a Novel Fixed Bed: Column Performance and Optimization

“…The isotherm properties give valuable information about the nature of the reactions, the adsorption forms, and the maximum capacity of KNTs as free particles. 32 The isotherm tests were conducted within the LVOX range from 25 to 300 mg/L and after adjusting the essential effective variables at certain values (pH 8, 0.02 g dosage, 150 mL volume, 24 h equilibration time, and 25 °C as the experimental temperature) ( Figure 6 ). The isotherm modeling of the results was accomplished by nonlinear fitting with Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) models and their equations represented by eqs 4 , 5 , and 6 , respectively: where C e , q e , and q max symbols are the remaining LVOX concentration in mg/L, the LVOX uptake capacity in mg/g, and the predicted maximum LVOX uptake capacity in mg/g.…”

“…The isotherm properties of KNTs during the uptake reactions of LVOX molecules were studied by batch adsorption experiments. The isotherm properties give valuable information about the nature of the reactions, the adsorption forms, and the maximum capacity of KNTs as free particles . The isotherm tests were conducted within the LVOX range from 25 to 300 mg/L and after adjusting the essential effective variables at certain values (pH 8, 0.02 g dosage, 150 mL volume, 24 h equilibration time, and 25 °C as the experimental temperature) (Figure ).…”