Synthesis of Acid-Modified Semi-Coke as an Efficient Adsorbent for the Adsorption of Valuable Phosphorus Compounds from Industrial Wastewater

Abstract

To purify and recycle the valuable phosphorus in chemical wastewater by a green method with high efficiency is of great significance in chemical engineering process. Herein, a type of activated semi-coke (ASC) was prepared by the one-pot hydrothermal process with HNO3 (2 mol·L-1). The material properties of ASC was studied by XRD, SEM, XPS, and FT-TR. Moreover, various kinetic models and isothermal adsorption models were used to describe the adsorption process. The results show that the adsorption capacity of ASC towards glyphosine was 26.1 mg·g-1, showing a great adsorption capacity towards the valuable phosphorus compounds in glyphosate mother liquor. Furthermore, the optimum adsorption conditions were as follows: the concentration of the ASC was 1 g·L-1, pH = 2.0 and the temperature was 298 K. Regeneration experimental results showed that the adsorption capacity of the ASC had decreased by about 30% after five times regeneration. The adsorption mechanism revealed that glyphosine was adsorbed mainly through electrostatic attraction and hydrogen bonding. In addition, the actual wastewater treatment exhibited that the phosphorus compound removal efficiency can reach 70% by ASC adsorption. This work not only provides a useful reference for the utilization of semi-coke but also possesses highly attractive for industrial applications due to the low price and simplicity of the synthesis process.

Keywords: Glyphosate mother liquor, Semi-coke, adsorption, Glyphosine