Synthetic musk is a common drug and personal care product. At present, there is no specific process for removing Jiale Musk (galaxolide, HHCB) from sewage, and the conventional sewage treatment technology has generally no effect on this component.

Therefore, the development of efficient, economical and environmentally-friendly materials for HHCB removal is an arduous challenge for environmental scientists at home and abroad. Biochar (charcoal produced from plant matter) has a large specific surface area and good chemical stability, and is difficult to be degraded by microorganisms. Its characteristics, to certain extent, can be utilized to realize waste resource treatment. 

Prof. ZHANG Qianru and her colleagues from the Institute of Applied Ecology (IAE), Chinese Academy of Sciences, used the excellent physical and chemical properties of ball-milled biochar to concentrate HHCB from aqueous solution onto the surface and pores of biochars by adsorption and hydrophobic partitioning. 

The sorption ability of the biochar prepared at high temperature was significantly enhanced by ball milling processing. For the low temperature biochars (300° C), ball milling only increases the external surface area.

For higher temperature biochars (500° C), however, ball milling simultaneously increases the external- and internal-surface area, thereby exposing its graphite structure and oxygen-containing functional groups, which in turn enhance the surface adsorption, π–π interaction, and pore filling.

For 500 °C wheat biochars (WS500), 77.9% of HHCB was removed due to surface adsorption, while 22.1% of HHCB was removed due to partitioning. For ball milled WS500 (BMSW500), 96.7% of HHCB was removed by surface adsorption, and the remaining 3.3% was removed due to the partitioning effect.  

This work highlights the potential of ball milling as an excellent engineering method for the improvement of biochar adsorption performance. 

The above findings were published in Science of the Total Environment entitled "Ball-milled biochar for galaxolide removal: Sorption performance and governing mechanisms".

This research was funded by the National Natural Science Foundation of China and the National Key Basic Research and Development Program.