高锰酸钾改性桉木生物炭对Pb(Ⅱ)的吸附特性

Adsorption Characteristics of Pb(Ⅱ)on Eucalyptus Biochar Modified by Potassium Permanganate

以桉木为原料,使用高锰酸钾对桉木生物炭(BC)进行改性,制备改性生物炭(KBC).对其进行表征,并进行了水溶液中Pb(Ⅱ)的静态吸附实验,探究了溶液pH、吸附剂投加量、吸附时间、温度和初始浓度对Pb(Ⅱ)的吸附效果影响.结果表明,最佳吸附反应pH为5,吸附在6 h达到饱和,当温度为25℃,Pb(Ⅱ)的初始浓度为100 mg·L^(-1),吸附剂投加量为0.06 g时,KBC对Pb(Ⅱ)的最大吸附量为83.059 mg·g^(-1),去除率为99.67%.KBC对Pb(Ⅱ)的吸附遵循二级动力学模型和Langmuir等温吸附模型,其是发生在均匀表面的单层吸附.采用BET、SEM-EDS、XRD、FT-IR和XPS对吸附剂进行表征分析,发现吸附机制主要是KBC含氧和KBC含锰基团通过络合作用和沉淀作用来吸附Pb(Ⅱ),以及在吸附过程中生物炭表面会形成—O—Pb—O—双齿配合物.因此,高锰酸钾改性BC可以作为一种很好的Pb(Ⅱ)吸附剂.

Eucalyptus biochar(BC)was prepared and potassium permanganate was used to modify the biochar(KBC).Static adsorption experiments on Pb(Ⅱ)in aqueous solution were carried out to investigate the effects of pH,adsorbent dosing,adsorption time,temperature,and initial concentration on the adsorption of Pb(Ⅱ).The results showed that the optimum pH was 5 while the adsorption reached saturation after 6 h.When the temperature was 25℃,the initial concentration of Pb(Ⅱ)was 100 mg·L^(-1)with an adsorbent dosage of 0.06 g;the maximum adsorption of Pb(Ⅱ)by KBC was 83.059 mg·g^(-1),with a removal rate of 99.67%.The adsorption of Pb(Ⅱ)by KBC followed the pseudo-second-order kinetic model and the Langmuir isothermal adsorption model,which is a monolayer adsorption occurring on a homogeneous surface.The adsorbents were characterized using the BET method,scanning electron microscopy and energy dispersive spectroscopy(SEM-EDS),X-ray diffraction(XRD),Fourier transformed infrared(FT-IR)and X-ray photoelectron spectroscopy(XPS).The adsorption mechanism of Pb(Ⅱ)by KBC oxygen-containing and manganese-containing groups was through complexation and precipitation,and the formation of—O—Pb—O—bidentate complexes on the surface of the biochar.Therefore,potassium permanganatemodified BC can be used as a good Pb(Ⅱ)adsorbent.