慈竹生物炭对水溶液中Cr(VI)的吸附性能

Adsorption performance of sinocalamus affinis biochar towards Cr(VI)in aqueous solution

以慈竹(sinocalamus affinis,SA)为原料,用磷酸对其进行活化,后经热解得到活化生物炭(activated sinocalamus affinis biochar,ASAB),用来吸附水溶液中的Cr(VI)。当溶液的初始pH为3时,Cr(VI)的初始质量浓度为20 mg·L^(−1),吸附剂投加量为1g·L^(−1)时,Cr(VI)去除率高达99.8%,剩余溶液中Cr(VI)的质量浓度低于废水排放标准(0.5 mg·L^(−1))。保持其他条件不变,改变Cr(VI)初始浓度,吸附剂的最大吸附容量可达236.2 mg·g^(−1)。以上结果均说明ASAB对废水中的Cr(VI)具有良好的吸附效果。采用SEM、BET、FTIR、XPS等表征方法对活化前、后的慈竹生物炭的化学结构和物理组成进行了表征。ASAB的比表面积是844.45 m^(2)·g^(−1),约为SAB(sinocalamus affinis biochar)的2.6倍,较高的比表面积可以提供更多的活性位点。本研究中,ASAB的除铬的机制包括静电作用和氧化还原作用。经过5个吸附-脱附循环后,ASAB对Cr(VI)的吸附效率依然可以达到80.9%。以上结果表明,作为1种高效的Cr(VI)吸附剂,ASAB可以用于处理废水中的Cr(VI)。

In this study,sinocalamus affinis(SA)was used as raw material to prepare biochar(ASAB)through activation with phosphoric acid and pyrolysis.The ASAB was used to adsorb Cr(VI)from aqueous solution.At the initial solution pH of 3,the initial Cr(VI)mass concentration of 20 mg·L^(−1)and the adsorbent dosage of 1 g·L^(−1),the removal rate of Cr(VI)was as high as 99.8%,and the remaining mass concentration of Cr(VI)in the solution was lower than the wastewater discharge standard(0.5 mg·L^(−1)).When only the initial concentration of Cr(VI)changed and other conditions maintained stable,the maximum adsorption capacity of the ASAB could reach 236.2 mg·g^(−1).All of these results indicated that the ASAB had a good adsorption effect of Cr(VI)in wastewater.The chemical structure and physical composition of the adsorbent were characterized by SEM,BET,FTIR,and XPS.The specific surface area of the ASAB was 844.45 m^(2)·g^(−1),which was about 1.6 times higher than that of the SAB(sinocalamus affinis biochar),and the higher specific surface area could provide more active sites.The mechanism of chromium removal by the ASAB included electrostatic and redox actions.After five adsorption-desorption cycles,the adsorption efficiency of the ASAB towards Cr(VI)could still maintain 80.9%.In conclusion,the ASAB is an efficient adsorbent and can be used to treat Cr(VI)in wastewater.