Photocatalysis is a promising solar energy conversion technology due to its potential applications in water treatment, searching for highly efficient photocatalytic materials is highly desirable. Herein, we have prepared a series of biochar(BC)/ZnFe₂O₄ magnetic nanocomposites by the calcination‐hydrothermal two‐step method. BC/ZnFe₂O₄ owns improved photoabsorption from 400 to 1300 nm. PL spectra of BC/ZnFe₂O₄ shows a weaker intensity compared with BC and ZnFe₂O₄, and BC/ZnFe₂O₄ generates a stronger photocurrent density (∼0.08 μA cm⁻²) than that of BC (0) or ZnFe₂O₄ (0.03 μA cm⁻²) under the visible light irradiation, implying efficient separation efficiency of photogeneration carriers. The investigation of pH (3, 5, 7, 9, 11) sensitivity of BC/ZnFe₂O₄ demonstrates that removal efficiency of Cr(VI) achieves the highest rate at pH=3. Under visible light irradiation, BC/ZnFe₂O₄ as photocatalyst can remove 80 % Cr(VI), higher than that of BC (0) or ZnFe₂O₄ (44 %). In addition, BC/ZnFe₂O₄ composites exhibit excellent cycling stability and can be easily separated for recycling due to its stability and unique magnetic properties. This work has presented a promising strategy in adsorption‐photocatalytic treatment of acidic wastewater containing heavy metals.

中文翻译：

---

吸附/光催化协同作用的BC / ZnFe2O4磁性纳米复合材料去除酸性废水中的Cr（VI）

光催化由于其在水处理中的潜在应用而成为有前途的太阳能转换技术，因此迫切需要寻找高效的光催化材料。在这里，我们通过煅烧-水热两步法制备了一系列生物炭（BC）/ ZnFe ₂ O ₄磁性纳米复合材料。BC / ZnFe ₂ O ₄具有从400到1300 nm的改进的光吸收。与BC和ZnFe ₂ O ₄相比，BC / ZnFe ₂ O _4的PL光谱显示出较弱的强度，并且BC / ZnFe ₂ O ₄产生更强的光电流密度（〜0.08μAcm ^-2）比可见光照射下的BC（0）或ZnFe ₂ O ₄（0.03μAcm ^-2）高，这意味着光生载流子的有效分离效率。BC / ZnFe ₂ O ₄对pH（3、5、7、9、11）敏感性的研究表明，Cr（VI）的去除效率在pH = 3时达到最高速率。在可见光照射下，BC / ZnFe ₂ O ₄作为光催化剂可以去除80％Cr（VI），高于BC（0）或ZnFe ₂ O ₄（44％）。另外，BC / ZnFe ₂ O ₄复合材料具有出色的循环稳定性，并且由于其稳定性和独特的磁性，可以很容易地分离出来进行回收利用。这项工作提出了一种有前途的吸附-光催化处理含重金属酸性废水的策略。