Adsorption is the common-used method to remove dyes from wastewater, and many efforts have been made to develop low-cost but excellent adsorbents. Here, calcium-rich biochar (CRB) as a low-cost adsorbent was directly prepared from crab shell via a simple pyrolysis process without any modification. Batch adsorption results suggested that CRB was among the dye adsorbents with highest adsorption capacities and fastest adsorption rate. Specifically, it showed high adsorption capacities of 12,502 and 20,317 mg/g for cationic malachite green and anionic Congo red, respectively. The adsorption equilibrium for Congo red onto CRB could be achieved as short as 2 min. Furthermore, the dye adsorption mechanism for CRB, as investigated by zeta potential and FTIR spectra, could be attributed to electrostatic attraction, hydrogen bonding and π-π interaction. Finally, this study suggested that, attributed to its cheap source, simple synthesis process and excellent adsorption performance, CRB was promising in dye removal.

吸附是从废水中去除染料的常用方法，并且已经进行了许多努力来开发低成本但优异的吸附剂。在这里，通过简单的热解工艺直接从蟹壳制备富含钙的生物炭（CRB）作为低成本吸附剂，而无需进行任何修饰。批吸附结果表明，CRB是染料吸附剂中吸附量最高，吸附速率最快的。具体而言，它对阳离子孔雀绿和阴离子刚果红分别具有12,502和20,317 mg / g的高吸附容量。刚果红在CRB上的吸附平衡可在2分钟之内完成。此外，通过ζ电势和FTIR光谱研究，CRB的染料吸附机理可归因于静电吸引，氢键和π-π相互作用。