Widespread application of dyes and disposal of their untreated effluents into water bodies adversely affect the ecosystem due to their complex aromatic structures and persistent nature. The present study aims to utilize the cotton stalks biochar (CSB) and its composite with zinc oxide nanoparticles (CSB/ZnONPs) to evaluate for the decontamination their batch scale potential of Congo red dye from wastewater. The characterization of CSB and CSB/ZnONPs was performed with Fourier-transform infra-red (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive X-ray (EDX) and point of zero charge (PZC) to get insight of their potential for the decontamination of CR. The effects of initial CR concentration (25–500 mg/L), dosage of CSB and CSB/ZnONPs (0.5–2 g/L), solution pH (2–10) and contact time (0–180 min) were evaluated on CR removal at temperature (25 ± 1.5 °C). The results disclosed that CSB/ZnONPs showed excellent adsorption potential (556.6 mg/g) in comparison with CSB (250 mg/g) and most of the other adsorbents previously studies in the literature. The equilibrium experimental data were equally explained with Freundlich and Langmuir isotherm models (R² > 0.98) while kinetic data demonstrated the best fit with pseudo second order model. The CSB/ZnONPs composite exhibited excellent reusability (89.65%) after five adsorption/desorption cycles for the sequestration of CR from contaminated systems. The present study demonstrated that metallic nanocomposite of CSB (CSB/ZnONPs) is an excellent candidate for the cost effective and environment friendly decontamination of CR from industrial wastewater and is suggested to be considered for the decontamination of other pollutants from the wastewater.

由于染料复杂的芳香结构和持久的特性，染料的广泛应用和将其未经处理的废水处理进入水体会对生态系统产生不利影响。本研究旨在利用棉秆生物炭（CSB）及其与氧化锌纳米颗粒的复合材料（CSB / ZnONPs）评估废水中刚果红染料的批量规模潜力。CSB和CSB / ZnONP的表征是通过傅立叶变换红外（FTIR）光谱，扫描电子显微镜，能量色散X射线（EDX）和零电荷点（PZC）进行的，以了解其潜力。 CR的去污。初始CR浓度（25–500 mg / L），CSB和CSB / ZnONPs剂量（0.5–2 g / L），在温度（25±1.5°C）下去除CR时，评估了溶液的pH值（2-10）和接触时间（0-180分钟）。结果表明，CSB / ZnONPs与CSB（250 mg / g）和以前在文献中研究过的大多数其他吸附剂相比，具有极好的吸附潜力（556.6 mg / g）。平衡实验数据用Freundlich和Langmuir等温线模型（R²  > 0.98），而动力学数据证明最适合拟二阶模型。CSB / ZnONPs复合材料经过五个吸附/解吸循环后，从污染的系统中螯合CR表现出优异的可重复使用性（89.65％）。本研究表明，CSB的金属纳米复合材料（CSB / ZnONPs）是工业废水中CR的经济有效且环境友好的净化方法的极佳候选者，建议将其用于净化废水中的其他污染物。