摘要
【目的】探究马尾松树皮纳米木质纤维素气凝胶吸附剂对Cr^(3+)、Cu^(2+)、Pb^(2+)、Ni^(2+)的吸附性能,阐明马尾松树皮和纳米木质纤维素气凝胶吸附重金属离子的相关机理,以更好地利用农林废弃物马尾松树皮制备出成本低廉、便于产业化的生物质吸附材料,为其大规模应用奠定理论基础。【方法】将抽提后的马尾松树皮绝干样品在80℃水浴加热搅拌条件下使用对甲苯磺酸溶液处理1 h,反应结束后趁热过滤并透析滤渣。滤渣样品通过微射流均质机20次,得到马尾松树皮纳米木质纤维素。固含量2%的马尾松树皮纳米木质纤维素样品-20℃冷冻120 min后进行冷冻干燥,得到马尾松树皮纳米木质纤维素气凝胶。研究马尾松树皮纳米木质纤维素气凝胶吸附剂对Cr^(3+)、Cu^(2+)、Pb^(2+)、Ni^(2+)的最大吸附容量(qe)以及其等温吸附特性、吸附热力学特性和吸附动力学特性。【结果】马尾松树皮纳米木质纤维素气凝胶吸附剂对Cr^(3+)、Cu^(2+)、Pb^(2+)和Ni^(2+)的最大吸附容量(qe)分别为132.7、130.4、186.7和123.4 mg·g^(-1)。马尾松树皮纳米木质纤维素气凝胶吸附Cr^(3+)符合Temkin等温吸附(R2=0.9901),且为不均匀的单层吸附。吸附热力学特性研究表明,马尾松树皮纳米木质纤维素气凝胶吸附Cr^(3+)的过程符合热力学规律,R2=0.9929,且为非自发复合吸附过程,升高温度对吸附过程的促进作用与放热反应对吸附过程的抑制作用甚至会出现相互抵消的情况。马尾松树皮纳米木质纤维素气凝胶吸附Cr^(3+)符合准二级动力学模型(R2=0.9910),其吸附Cr^(3+)的速率主要受化学作用而非物质传输步骤影响,特别是二者之间电子的化学分享或共价键交换等过程。【结论】基于廉价的生物质——马尾松树皮制备的马尾松树皮纳米木质纤维素气凝胶可作为重金属离子的有效吸附剂,表现出较为理想的吸附容量,静态吸附涉及的条件较为简单,具有一定的可试验推广性,马尾松树皮基吸附剂的开发也可推动廉价生物质的资源化利用。马尾松树皮和纳米木质纤维素气凝胶2种吸附剂的吸附性能稳定可靠,有望通过优化工艺提升性能;但是需要基于大规模甚至中试规模试验才能检验其有效性,进而指导工艺优化,得到性能更加出色的马尾松树皮纳米木质纤维素气凝胶作为重金属离子吸附剂。
【Objective】This paper was carried out to explore the adsorption performance of the Pinus massoniana nano-lignocellulose aerogel adsorbent for Cr^(3+)/Cu^(2+)/Pb^(2+)/Ni^(2+),and clarify the related mechanisms of P.massoniana bark and nano-lignocellulose aerogel adsorbing heavy metal ions,with aims to make better use of agricultural and forestry waste P.massoniana bark to prepare low-cost and easy-to-industrial biomass adsorption materials,and to lay a theoretical foundation for its large-scale application.【Method】The extracted dry sample was treated with p-toluenesulfonic acid solution for 1 hour under the conditions of heating and stirring in a water bath at 80℃.Then the reaction materials were filtered and filter residue was dialyzed.The filter residue sample was homogenized 20 times by a microfluidizer to obtain nano-lignocellulose samples.The samples with a solid content of 2%were frozen at-20℃for 120 min,and then freeze-dried to obtain aerogel samples.The adsorption properties of the aerogel were studied,including the maximum qe of heavy metal ions as Cr^(3+),Cu^(2+),Pb^(2+)and Ni^(2+),the isothermal adsorption characteristics,adsorption thermodynamics and adsorption kinetics.【Result】The maximum qe of different heavy metal ions of Cr^(3+),Cu^(2+),Pb^(2+)and Ni^(2+) were 132.7,130.4,186.7 and 123.4 mg·g^(-1),respectively.The adsorption of Cr^(3+)on P.massoniana bark nano-lignocellulosic aerogel was consistent with the Temkin isothermal adsorption(R2=0.9901),and it was a non-uniform monolayer adsorption.The adsorption thermodynamic characteristics indicated that the adsorption process of Cr^(3+) was accordant with the thermodynamic law,with R2=0.9929.Moreover,the process was a non-spontaneous composite adsorption,and the promotion effects of the increasing temperature on the adsorption process and the inhibition effects of the exothermic reaction on the adsorption process may even cancel each other out.At the same time,the adsorption of Cr^(3+) on the nano-lignocellulosic aerogel of P.massoniana bark was accordant with the pseudo-second-order kinetic model(R2=0.9910),the adsorption rate of Cr^(3+) was mainly affected by chemical interaction rather than material transport steps,especially the process of chemical sharing or covalent bond exchange between the two.【Conclusion】The nano-lignocellulosic aerogel of P.massoniana bark prepared from cheap biomass-mass pine bark can be used as an effective adsorbent for heavy metal ions,showing an ideal adsorption capacity.The conditions involved in static adsorption experiments are also relatively simple.Therefore,it can be experimentally popularized to some extent.The development of the adsorbents can also promote the resource utilization of low-cost biomass.The adsorption performance of P.massoniana bark and nano-lignocellulose aerogel is stable and reliable,and the performance is expected to be improved by optimizing the processes.However,both of the above two points need to test their effectiveness based on large-scale or even pilot-scale experiments,so further to guide the process optimization to obtain better performance of aerogel as a heavy metals ion adsorbent.
作者
王海洋
马千里
Wang Haiyang;Ma Qianli(Yanching Institute of Technology,Langfang 065201;International Center for Bamboo and Rattan,Beijing 100102)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2021年第7期166-174,共9页
Scientia Silvae Sinicae
基金
国际竹藤中心基本业务费项目(2060302010408018)。
