Study on the Preparation of Magnetic Pine Needle Biochar and Its Adsorption Performance for the Dye

Abstract

The agricultural and forestry waste pine needle was selected to prepare the biochar which magnetized by the Fe₃O₄ to treat the typical wastewaters of the dye methylene blue (MB) and carmine (P4R) in view of the problem of quick increasing dye wastewater caused by the rapid development of textile, printing and dyeing industries, and the research result showed the experimental values of the maximum adsorption capacity of modified biochar for MB and P4R were 465.6mg·g^-1 and 336.6mg·g^-1 respectively. When the dosage of MBC is 0.010g and 0.015g, both the removal rate and the adsorption capacity can be maintained at a high level. Lower pH is conducive to the adsorption of P4R, and a higher pH is conducive to the adsorption of MB. As the adsorption time and initial dye concentration increase, the adsorption capacity of both dyes increases. As the temperature increases, the amount of MB adsorption increases, while the amount of P4R adsorption decreases and the adsorption of MB by MBC is a high-temperature spontaneous adsorption process, and the adsorption of P4R is a low-temperature spontaneous adsorption. The Langmuir model can better describe the adsorption process of MBC to MB, which is a single-layer adsorption, and the Freundlich adsorption model can better describe the adsorption process of MBC to P4R, which is a multi-layer adsorption. The adsorption of MB and P4R by MBC conforms to the quasi-second-order kinetic model.