Punjongharn Pimol, Meevasana Khanidtha, Pavasant Prasert
Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
J Environ Sci (China). 2008;20(6):760-8. doi: 10.1016/s1001-0742(08)62124-5.
Green macroalga Caulerpa lentillifera was found to have reasonable adsorption capacity for basic dyes, Astrazon Blue FGRL (AB), Astrazon Red GTLN (AR), and Astrazon Golden Yellow GL-E (AY). The initial dye concentration was in the range of 100-1,800 mg/L. The dried algal sorbent was ground and sieved into 3 sizes: S (0.1-0.84 mm), M (0.84-2.0 mm), and L sizes (larger than 2.0 mm). For all conditions examined in this work (at 25 degrees C in batch systems), the adsorption reached equilibrium within the first hour. The kinetic data corresponded well with the pseudo second order kinetic model where the rate constant, k2, decreased as the sorbent size increased for all dyes. The adsorption isotherms followed both Langmuir and Freundlich models. Among three sorbent sizes, S size gave the highest adsorption capacity followed by M and L sizes. A reduction of sorbent size increased the specific surface area for mass transfer, and also increased the total pore volume, thus providing more active sites for adsorption. The adsorption of AB was adversely influenced by the protonation of algal surface at low pH. On the other hand, the adsorption of AR and AY could be due to weak electrostatic interaction, which was not significantly affected by pH. Increasing salinity of the system caused a decrease in adsorption capacity possibly due to the competition between Na+ and the dye cations for the binding sites on algal surface. Moreover, an increase in salinity generated a compressed electrical double layer on the algal surface which exerted repulsive force, retarding the adsorption of positive charged molecules such as the basic dyes.
研究发现，绿藻长茎葡萄蕨藻对碱性染料阿斯特拉宗蓝FGRL（AB）、阿斯特拉宗红GTLN（AR）和阿斯特拉宗金黄GL-E（AY）具有合理的吸附能力。初始染料浓度范围为100 - 1800 mg/L。将干燥的藻类吸附剂研磨并筛分为3种尺寸：S（0.1 - 0.84 mm）、M（0.84 - 2.0 mm）和L尺寸（大于2.0 mm）。对于本研究中考察的所有条件（在25℃的间歇系统中），吸附在第一小时内达到平衡。动力学数据与伪二级动力学模型吻合良好，其中对于所有染料，速率常数k2随着吸附剂尺寸的增加而降低。吸附等温线符合朗缪尔模型和弗伦德利希模型。在三种吸附剂尺寸中，S尺寸的吸附容量最高，其次是M尺寸和L尺寸。吸附剂尺寸减小增加了传质的比表面积，也增加了总孔体积，从而提供了更多的吸附活性位点。在低pH值下，藻类表面的质子化对AB的吸附有不利影响。另一方面，AR和AY的吸附可能是由于弱静电相互作用，pH对其影响不显著。系统盐度增加导致吸附容量降低，这可能是由于Na +与染料阳离子在藻类表面结合位点上的竞争。此外，盐度增加会在藻类表面产生压缩的双电层，施加排斥力，阻碍碱性染料等带正电分子的吸附。
