Department of Chemistry, University of Sahiwal, Sahiwal, 57000, Pakistan.
Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Islamabad, 44000, Pakistan.
Environ Res. 2022 Dec;215(Pt 3):114398. doi: 10.1016/j.envres.2022.114398. Epub 2022 Sep 26.
Industrial wastewater is causing serious health problems due to presence of large concentrations of toxic metals. Removal of these metals is still a big challenge using pristine natural biopolymers due to their low surface area, water solubility, and poor recovery. Developing biopolymeric composites with other materials has attained attention because they possess a high surface area and structural porosity, high reactivity, and less water solubility. In simple words, biopolymeric nanohybrids have great adsorption capacity for heavy metals. Biopolymeric materials are abundant, low cost, biodegradable, and possess different functional moieties (carboxyl, amine, hydroxyl, and carbonyl) which play a vital role to adsorb metal ions through various inter-linkages (i.e., electrostatic, hydrogen bonding, ion exchange, chelation, etc.). Biopolymeric nanohybrids have been proven a potent tool in environmental remediation such as the abatement of heavy metal ions from polluted water. Herein, we have reported the adsorption potential of various biopolymers (cellulose, chitosan, pectin, gelatin, and silk proteins) for the removal of heavy metals. This review discusses the suitability of biopolymeric nanohybrids as an adsorbent for heavy metals, their synthesis, modification, adsorption potential, and adsorption mechanism along with best fitted thermodynamic and kinetic models. The influence of pH, contact time, and adsorbent dose on adsorption potential has also been discussed in detail. Lastly, the challenges, research gaps and recommendations have been presented. This review concludes that biopolymers in combination with other materials such as metal-based nanoparticles, clay, and carbon-based materials are excellent materials to remove metallic ions from wastewater. Significant adsorption of heavy metals was obtained at a moderate pH (5-6). Contact time and adsorbent dose also affect the adsorption of heavy metals in certain ways. The Pseudo-first order model fits the data for the initial period of the first step of the reaction. Kinetic studies of different adsorption processes of various biopolymeric nanohybrids described that for majority of bionanohybrids, Pseudo-second order fitted the experimental data very well. Functionalized biopolymeric nanohybrids being biodegradable, environment friendly, cost-effective materials have great potential to adsorb heavy metal ions. These may be the future materials for environmental remediation.
工业废水中含有大量的有毒金属，这些金属导致了严重的健康问题。由于天然生物聚合物的比表面积低、水溶性差、回收效果差，因此使用它们去除这些金属仍然是一个巨大的挑战。开发具有其他材料的生物聚合物复合材料已经引起了人们的关注，因为它们具有高比表面积和结构孔隙率、高反应性和低水溶性。简单来说，生物聚合物纳米杂化物对重金属具有很强的吸附能力。生物聚合物材料丰富、成本低、可生物降解，并且具有不同的功能基团（羧基、氨基、羟基和羰基），这些基团通过各种相互作用（例如静电、氢键、离子交换、螯合等）在吸附金属离子方面起着至关重要的作用。生物聚合物纳米杂化物已被证明是环境修复的有效工具，例如去除受污染水中的重金属离子。本文报道了各种生物聚合物（纤维素、壳聚糖、果胶、明胶和丝蛋白）对重金属去除的吸附潜力。本文综述了生物聚合物纳米杂化物作为重金属吸附剂的适用性、它们的合成、修饰、吸附潜力和吸附机制，以及最佳拟合的热力学和动力学模型。还详细讨论了 pH 值、接触时间和吸附剂剂量对吸附潜力的影响。最后，提出了挑战、研究空白和建议。本文综述得出的结论是，生物聚合物与金属基纳米粒子、粘土和碳基材料等其他材料结合是从废水中去除金属离子的极好材料。在中等 pH 值（5-6）下，可以获得重金属的显著吸附。接触时间和吸附剂剂量也以某种方式影响重金属的吸附。准一级动力学模型适合反应第一步的初始阶段的数据。不同生物聚合物纳米杂化物的各种吸附过程的动力学研究表明，对于大多数生物纳米杂化物，准二级动力学模型非常适合实验数据。功能化生物聚合物纳米杂化物是可生物降解、环境友好、具有成本效益的材料，具有吸附重金属离子的巨大潜力。这些可能是环境修复的未来材料。
