废轮胎炭黑的改性及其在锌回收与Cr(VI)吸附中的应用

Modification of Waste Tire Carbon Black and Its Application in Zinc Recovery and Cr(VI) Adsorption

摘要: 废轮胎热解炭黑的高灰分限制了其高值化应用，且传统酸浸工艺常导致二次污染与资源浪费。本研究以HCl酸洗与NaOH水热法对废轮胎热解炭黑(waste tire pyrolysis carbon black，CBp)进行联合改性，优化除灰工艺并实现锌回收。结果表明，最佳除灰条件为HCl浓度4 mol∙L⁻¹、反应温度60℃、反应时间4 h、液固比12 mL∙g⁻¹，随后经20% NaOH在180℃下水热处理10 h，灰分降至1.73%；在酸浓度 ≥ 2 mol∙L⁻¹时，Zn²⁺在酸洗液中实现高效富集，酸洗液循环使用7次后Zn²⁺达到饱和，可有效减少酸耗与废液排放；改性炭黑(CBp-OH)在pH = 2℃、25℃条件下，通过静电吸引、还原与络合作用吸附Cr(VI)，吸附容量为80.43 mg∙g⁻¹，吸附容量相较于原始CBp提升2.7倍。本研究通过“除灰–富锌–吸附”协同策略，实现了废轮胎热解炭黑的高值化利用与重金属废水治理的结合，为固废高值化与环境修复提供了新的技术思路。

Abstract: The high ash content of waste tire pyrolysis carbon black severely restricts its high-value applications, and traditional acid leaching processes often lead to secondary pollution and resource wastage. In this study, waste tire pyrolysis carbon black (CBp) was used as the raw material for a combined modification process involving HCl acid washing and NaOH hydrothermal treatment to optimize ash removal and achieve zinc recovery. The results showed that the optimal ash removal conditions were achieved with an HCl concentration of 4 mol∙L⁻¹, a reaction temperature of 60˚C, a reaction time of 4 hours, and a liquid-to-solid ratio of 12 mL∙g⁻¹. This was followed by hydrothermal treatment with 20% NaOH at 180˚C for 10 hours, which reduced the ash content to 1.73%. When the acid concentration was ≥ 2 mol∙L⁻¹, Zn²⁺ was efficiently enriched in the acid washing solution, and after seven cycles of solution reuse, Zn²⁺ reached saturation, effectively reducing both acid consumption and waste liquid discharge. The modified carbon black (CBp-OH) exhibited a significantly improved adsorption capacity of 80.43 mg∙g⁻¹ for Cr(VI) at pH = 2˚C and 25˚C, 2.7 times higher than that of pristine CBp. The adsorption mechanisms involved electrostatic attraction, reduction, and complexation. Through the synergistic strategy of “ash removal—zinc enrichment—adsorption”, this study achieved an effective integration of high-value utilization of waste tire pyrolysis carbon black and heavy metal wastewater treatment, providing a novel technical approach for solid waste valorization and environmental remediation.