碱-柠檬酸改性木膜对四环素的吸附性能

Adsorption performance of alkali-citric acid modified wood membranes towards tetracycline

含羧基(—COOH)的无毒柠檬酸(citric acid,CA)改性木膜(wood membranes,WMs)在水处理领域具有广阔的应用前景。然而,由于木质纤维素的结构特点,—COOH很难引入木膜壁内。对木膜进行不同浓度NaOH的预处理,再与柠檬酸进行酯化反应,用于吸附水中的四环素(tetracycline,TC)。通过碱液预处理,有利于CA与木质纤维素的酯化反应,使得木膜的—COOH含量大幅地提高。TC吸附曲线表明,当碱浓度为6%以及TC出水浓度为0.5 mg·L^(-1)时,改性木膜的有效过滤体积为1968 BV(bed volume,BV),比未改性木膜的吸附率提高了约48倍;在4次循环后改性木膜对TC的吸附率也可达97%。当出水浓度为0~0.5 mg·L^(-1)时,水处理成本为0.0360~0.08325元·m^(-3)。因此,改性木膜在去除水中TC方面具有很好的应用前景。以上研究结果可为解决木膜应用中的关键局限性,设计具有环境友好、经济和有效的环境修复膜材料提供参考。

Innocuous citric acid(CA)modified wood membranes(WMs)with carboxylic groups(—COOH)have broad application prospects in water purification.However,due to the structural characteristics of lignocellulose,carboxylic groups are difficult to introduce into the wood membrane wall.Herein,the wood membranes were modified via the pretreatment with various NaOH concentrations and the subsequent esterification with CA for tetracycline(TC)adsorption in water.The pretreatment of alkali was beneficial to the esterification of CA and lignocellulose,and the content of carboxylic groups in wood membrane increased greatly.The TC adsorption curves showed that at the alkali concentration of 6%and TC effluent concentration of 0.5 mg·L^(-1),the modified WM had effective filtration volume of 1968 BV(bed volume),which was about 48 times higher than unmodified WM.The TC adsorption efficiency by modified WM could reach up to 97%after four cycles.At effluent TC concentrations of 0~0.5 mg·L^(-1),the cost of water treatment is 0.0360~0.08325 yuan·m^(-3).The modified WM has a great potential in TC removal from water.The study provides effective strategies reference for overcoming critical limitations related with the application of WM and design an environmentally friendly,economical and effective membrane material for environmental remediation.