摘要
【目的】研究单叶省藤材水分吸附的变化规律,阐明藤材内部水分吸附变化的深层机理,为解决藤材安全贮存与合理加工利用过程中由水分吸附和散失引起的质量问题提供理论依据。【方法】采用动态水蒸气吸附仪测定藤材的水分吸附行为,选择H-H模型、GAB模型、Halsey模型、Henderson模型、Oswin模型和Smith模型对平衡含水率(EMC)数据进行非线性拟合并评价其拟合效果,运用最佳拟合模型分析水分吸附过程中平衡含水率、单分子层吸附水和多分子层吸附水的变化规律。【结果】单叶省藤材水分吸附等温线呈“S”形,属于第Ⅱ类等温线,具有多分子层吸着特性;与木、竹材相似,单叶省藤材在整个吸湿过程中表现出明显的吸湿滞后现象,且其吸滞滞后率在相对湿度(RH)80%时达0.8,早于木材(RH=95%);6种模型中,H-H模型和GAB模型对数据的拟合度最高,R2均高于0.99;H-H模型中代表含有单位摩尔数吸附位的绝干藤材质量参数(W1)显著低于木、竹材,在吸湿阶段,当RH<60%时,主要以单分子层吸附为主,单分子层吸附水含量为6.80%;通过GAB模型计算得出藤材吸湿阶段的水分可及内比表面积(S)和单分子层吸附水含量(W0)分别为293 m^(2)·g^(-1)和7.67%,均大于木、竹材,分析其原因可能是单叶省藤材的纤维细胞壁薄腔大,相邻薄壁细胞之间的空隙较大且结晶度较小;由H-H模型和GAB模型推测出的纤维饱和点(FSP)分别为20.28%和18.67%。【结论】H-H模型和GAB模型可用于描述单叶省藤材水分吸附等温线,拟合度较高;单叶省藤材的化学组分含量、解剖构造和结晶度是影响其单分子层吸附水含量的主要因素,单叶省藤材单分子层吸附水含量略高于竹材,水分可及内比表面积大于竹材。
【Objective】Studying the hygroscopic behavior and clarifying of the mechanism of water adsorption in Calamus simplicifolius cane are important to provide the theoretical guidance for solving the quality problem caused by water adsorption and desorption in processing and utilization of rattan.【Method】In this study,the dynamic vapor sorption apparatus was used to measure the water adsorption behavior of cane.The equilibrium moisture content(EMC)data were nonlinearly fitted by Hailwood-Horrobin(H-H)model,Guggenheim-Anderson-deBoer(GAB)model,Halsey model,Henderson model,Oswin model,and Smith model,and the fitting effects were also evaluated.The optimal fitting models were used to analyze the changes of EMC,monolayer and polylayer water adsorption during sorption processes.【Result】The sorption isotherms of C.simplicifolius cane exhibited a sigmoidal shape,belonged to the second category of moisture adsorption isotherms and had the characteristics of multi-molecular layer adsorption.Similar to wood and bamboo,C.simplicifolius cane existed hygroscopic hysteresis,its hysteresis coefficient reached 0.8 at relative humidity(RH)of 80%,which was earlier than that of wood(RH=95%).Among the 6 models,H-H model and GAB model had the highest data fitting degree,with R^(2) both over 0.99.In the H-H model,the parameter W1,which means the apparent molecular mass of the dry rattan per sorption sites,was significantly less than that of wood and bamboo.In the hygroscopic stage,the adsorption was mainly monolayer water adsorption,and the value was 6.80%at RH<60%.The water accessible specific surface area(S)and monolayer water adsorption(W_(0))in the hygroscopic stage of rattan estimated by GAB model were 293 m^(2)·g^(-1) and 7.67%,respectively,which were greater than those of wood and bamboo.The reason might be that the fiber cell wall of rattan was thinner,the cell lumen was larger,the spaces between adjacent parenchyma cells were larger,and the cellulose crystallinity was smaller as well.The fiber saturation point values o
作者
杨利梅
刘杏娥
江泽慧
田根林
杨淑敏
尚莉莉
Yang Limei;Liu Xing’e;Jiang Zehui;Tian Genlin;Yang Shumin;Shang Lili(International Center for Bamboo and Rattan,Beijing 100102;School of Architectural and Artistic Design,Henan Polytechnic University,Jiaozuo 454000)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2021年第7期150-157,共8页
Scientia Silvae Sinicae
基金
国际竹藤中心基本业务费项目(20618-27)
河南理工大学博士科研基金项目(B2021-44,B2017-39)
河南省科技攻关计划项目(212102310960)。
关键词
单叶省藤材
水分吸附特性
等温吸附模型
单分子层吸附
多分子层吸附
Calamus simplicifolius cane
water adsorption characteristics
isothermal adsorption model
monolayer water adsorption
polylayer water adsorption
