Abstract
This report deals with converting the agriculture waste (rice straw) to environmental cleaner materials (biochar) using airless pyrolysis followed by eco-friendly activation. The biochar (p-Biochar) obtained after pyrolysis step (poorly active material) was activated using wet attrition method to give m-Biochar (highly active materials). The both p-Biochar and m-Biochar were characterized in detail and utilized for MB and CV dye removal from aqueous solution. Various parameters affecting the adsorption process such as dye concentration, adsorbent dose, contact time, temperature, NaCl dose and pH were investigated. The adsorption isotherm was well fitted using Langmuir isotherm, and the maximum adsorption capacity is 90.91 and 44.64 mg/g, for MB and CV dyes, respectively. The contact time data obtained showed that the two dyes were poorly adsorbed over p-Biochar. The equilibrium was reached quickly in 15 min for MB dye and 20 min for CV dye using the m-Biochar, and removal percent was 94.45 and 92.70% for MB and CV dyes, respectively. Moreover, the kinetic isotherm presented very well fitted by pseudo-second-order model. In addition, the adsorption percent increases with further increasing the pH value. Finally, we observed that m-Biochar highly adsorbs the MB dye compared with the CV dye over all experimental conditions.
Highlights
Dyes are considered as colored ionized aromatic organic materials
In the last decade, burning this in huge quantities by farmers has added an additional source of greenhouse gases (GHG) emitted from agricultural sector and caused “the black cloud,” a thick black smog that can be seen over the Cairo sky every autumn
We show that the removal percent increases from 34.70 to 95.06% for methylene blue (MB) and from 29.32 to 95.13% for crystal violet (CV) when the adsorbent dose increases from 0.01 to 0.05 g; this increase in %R can be explained by improving adsorbent surface area and rising in the available active sites for the adsorption (Da Silva et al 2018)
Summary
Dyes are required by numerous industries such as textile, leather, paper, plastic, and food. The effluents from these industries contain various types of contaminated, dye. Adsorption is considered a promising technique, in which the contaminants were transferred from the solvent to the solid phase. Based on this consideration, the adsorption appears to be simple to design, available, easy to operate, does not produce toxic materials and does not require high cost. Activated carbon is the most applicable adsorbent used in industry; this is attributed to its adsorptive efficiency, high surface area, and porous structure. Many researchers have prepared activated carbon from various waste agriculture products
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