A series of the magnetic CuFe2O4-loaded corncob biochar (CuFe2O4@CCBC) materials was obtained by combining the two-step impregnation of the corncob biochar with the pyrolysis of oxalate. CuFe2O4@CCBC and the pristine corncob biochar (CCBC) were characterized using XRD, SEM, VSM, BET, as well as pHZPC measurements. The results revealed that CuFe2O4 had a face-centered cubic crystalline phase and was homogeneously coated on the surface of CCBC. The as-prepared CuFe2O4@CCBC(5%) demonstrated a specific surface area of 74.98 m2·g−1, saturation magnetization of 5.75 emu·g−1 and pHZPC of 7.0. The adsorption dynamics and thermodynamic behavior of Pb(II) on CuFe2O4@CCBC and CCBC were investigated. The findings indicated that the pseudo-second kinetic and Langmuir equations suitably fitted the Pb(II) adsorption by CuFe2O4@CCBC or CCBC. At 30 °C and pH = 5.0, CuFe2O4@CCBC(5%) displayed an excellent performance in terms of the process rate and adsorption capacity towards Pb(II), for which the theoretical rate constant (k2) and maximum adsorption capacity (qm) were 7.68 × 10−3 g·mg−1··min−1 and 132.10 mg·g−1 separately, which were obviously higher than those of CCBC (4.38 × 10−3 g·mg−1·min−1 and 15.66 mg·g−1). The thermodynamic analyses exhibited that the adsorption reaction of the materials was endothermic and entropy-driven. The XPS and FTIR results revealed that the removal mechanism could be mainly attributed to the replacement of Pb2+ for H+ in Fe/Cu–OH and –COOH to form the inner surface complexes. Overall, the magnetic CuFe2O4-loaded biochar presents a high potential for use as an eco-friendly adsorbent to eliminate the heavy metals from the wastewater streams.
1.河北师范大学化学与材料科学学院,石家庄 050024;2.河北省无机纳米材料重点实验室,石家庄 050024) 摘 要: 以松木碱解液代替 NaOH 溶液作为锌盐沉淀剂,采用水热法制备了 Zn2SiO4-ZnO-生物炭三元复合材料 (SOB-x-y,x 代表松木粉的用量,y 代表 NaOH 浓度),通过不同手段对样品进行了表征,研究了光催化 H2O2 降 解甲硝唑的性能。结果表明,制备的催化剂由枣核状硅锌矿型 Zn2SiO4 介晶、多边形六方晶相 ZnO 和松木生物炭 构成;与纯六方晶相 ZnO 相比,它具有更大的比表面积与孔容、更小的带隙能和更弱的荧光发射,因而具有更好 的光催化活性。 Zn2SiO4-ZnO-生物炭对甲硝唑的光催化 H2O2 降解过程符合准一级动力学方程, 其催化活性随 NaOHAbstract: Using pine alkali hydrolysate to replace NaOH solution as zinc salt precipitator, the Zn2SiO4-ZnO-Biochar (SOB-x-y, x is the dosage of pine powder, y is the concentration of NaOH) ternary composites were prepared by hydrothermal method. The photocatalysts were characterized through different methods. The degradation of metronidazole over the H2O2 photocatalysis was studied. The results showed that the as-prepared photocatalysts were composed of jujube-type willemite Zn2SiO4 mesocrystals, hexagonal ZnO and pine biochar. Compared with pure hexagonal ZnO, the SOB-x-y photocatalysts has better H2O2 photocatalytic activity due to the higher surface area and pore volume, lower band gap energy, lower PL emission peak intensity. The metronidazole degradation using the H2O2 photocatalysis was well-fitted to a pseudo-first-order kinetic model by SOB-x-y. Its catalytic activity increased with the increase of NaOH concentration, and increased at first and then decreased with the increase of pine flour content. The SOB-3-4 has best photocatalytic acitivity. The rate constant (k) and degradation rate (η) of SOB-3-4 increase with the decrease of pH, increase with the increase of H2O2 concentration, increase first and then decrease with the increase of catalyst dosage. The degradation rate of metronidazole gradually decreases with the increase of its initial concentration. Under the optimal condition (pH=3, catalyst dosage of 0.4 g/L , H2O2 dosage of 80 mmol/L, initial metronidazole concentra-
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