小球藻藻渣TEMPO法制备纤维素纳米纤维及阳离子染料吸附研究

Reuse of chlorella waste for the production ofcellulose nanocrystals through TEMPO-mediated oxidation andits application in cationic dyes adsorption

纤维素是自然界最丰富的生物大分子,普遍存在于植物细胞的细胞壁中。由纤维素分解制备的纳米纤维素因其优越的特性可被用作吸附剂进行污水处理。小球藻细胞壁中纤维素含量丰富而几乎没有木质素,是制备纳米纤维的优质原料。通过TEMPO介导氧化法从小球藻藻渣中制备了羧基化纤维素纳米纤维(TCNF),其平均直径约为2 nm,长度在300 nm左右,羧基含量为1.54 mmol/g。并以亚甲基蓝(MB)为模型染料进行了TCNF的吸附研究。结果表明,TCNF对MB吸附符合伪二级吸附动力学模型,在吸附80 min后基本达到平衡;TCNF对MB的吸附受pH影响较大,pH=8时具有最大吸附量;TCNF对MB的吸附量随MB浓度升高呈线性增加,当浓度高于10 mg/L后吸附趋于饱和;吸附等温线分析发现TCNF对MB的吸附符合Langmuir模型,表明TCNF表面均匀,表面不同位置的吸附能变化不大,为单层吸附。总之,利用小球藻藻渣制备TCNF进行工业废水中阳离子染料的去除,是一种简单且很有前途的的方案。

Cellulose was the most abundant biological molecule in nature,as a major component of plant cell wall.Nanocellulose isolated through disintegration of cellulose fibers could be used as an adsorbent for wastewater treatment due to its excellent properties.Owing to its high cellulose content and almost without lignin in the cell walls,Chlorella was a good raw material for preparing nanocellulose.In this study,Chlorella-residual based TEMPO-oxidized cellulose nanofibers(TCNF)were prepared through TEMPO-mediated oxidation processes under gentle mixing without high-energy mechanical treatments.The average diameter of TCNF is about 2 nm,whereas its average length was about 300 nm,and the carboxyl content is 1.54 mmol/g.Moreover,methylene blue(MB)was used as a model dye to measure the adsorption capacity of TCNF.The adsorption capacity is almost saturated when TCNF contacted MB for 80 min,and the adsorption kinetics coincide with the pseudo-secondary kinetics model.The adsorption of TCNF on MB is greatly affected by the pH value,with a maximum value at pH=8.The initial concentration of MB considerably affects its adsorption on TCNF.Below the initial concentration of 10 mg/g,adsorption of TCNF considerably increases with the increase in the initial concentration of MB.And when the concentration is higher than 10 mg/L,the adsorption tends to be saturated.Based on the sorption isotherms analysis of TCNF,the Langmuir model fits best with the experimental data.Thus,TCNF surfaces are uniform and monolayer adsorption occurred.In conclusion,the preparation of TCNF from Chlorella-residual is a simple and promising scheme for the removal of cationic dyes from industrial wastewater.