Adsorption of Cr(VI) from wastewater by iron-modified coconut shell biocharJiangping Bu, Wenyu Li, Ning Niu, Ning Guo, Hao Zhou, Cheng Chen and Aifang DingE3S Web Conf., 248 (2021) 01059DOI: https://doi.org/10.1051/e3sconf/202124801059