Blockx Jonas, Verfaillie An, Deschaume Olivier, Bartic Carmen, Muylaert Koenraad, Thielemans Wim
Sustainable Materials Laboratory, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk Etienne Sabbelaan 53 box 7659 8500 Kortrijk Belgium
Laboratory for Aquatic Biology, KU Leuven, Campus Kulak Kortrijk Etienne Sabbelaan 53 box 7659 8500 Kortrijk Belgium
Nanoscale Adv. 2021 Jun 14;3(14):4133-4144. doi: 10.1039/d1na00102g. eCollection 2021 Jul 13.
Flocculation is a widely used technology in industry including for wastewater treatment and microalgae harvesting. To increase the sustainability of wastewater treatment, and to avoid contamination of the harvested microalgal biomass, there is a need for bio-based flocculants to replace synthetic polymer flocculants or metal salt coagulants. We developed the first cellulose nanocrystalline flocculant with a grafted cationic point charge, glycine betaine (,,-trimethylglycine) grafted cellulose nanocrystals (CNCs) effective for the flocculation of kaolin (a model system for wastewater treatment), the freshwater microalgae , and the marine microalgae . We successfully grafted glycine betaine onto CNCs using a one-pot reaction using a tosyl chloride activated esterification reaction with a degree of substitution ranging from 0.078 ± 0.003 to 0.152 ± 0.002. The degree of substitution is controlled by the reaction conditions. Flocculation of kaolin (0.5 g L) required a dose of 2 mg L, a comparable dose to commercial polyacrylamide-based flocculants. Flocculation was also successful for freshwater as well as marine microalgae (biomass concentration about 300 mg L dry matter), although the flocculation efficiency of the latter remained below 80%. The dose to induce flocculation (DS = 0.152 ± 0.002) was 20 mg L for the freshwater and 46 mg L for the marine , comparable to other bio-based flocculants such as chitosan or TanFloc.
絮凝是一种在工业中广泛应用的技术，包括用于废水处理和微藻收获。为了提高废水处理的可持续性，并避免收获的微藻生物质受到污染，需要生物基絮凝剂来替代合成聚合物絮凝剂或金属盐凝聚剂。我们开发了第一种带有接枝阳离子点电荷的纤维素纳米晶絮凝剂，即甘氨酸甜菜碱（三甲基甘氨酸）接枝纤维素纳米晶（CNCs），它对高岭土（废水处理的模型体系）、淡水微藻和海洋微藻的絮凝有效。我们使用甲苯磺酰氯活化酯化反应的一锅法反应成功地将甘氨酸甜菜碱接枝到CNCs上，取代度范围为0.078±0.003至0.152±0.002。取代度由反应条件控制。絮凝高岭土（0.5 g/L）需要2 mg/L的剂量，这与基于商业聚丙烯酰胺的絮凝剂相当。对于淡水和海洋微藻（生物质浓度约为300 mg/L干物质）的絮凝也取得了成功，尽管后者的絮凝效率仍低于80%。诱导絮凝的剂量（DS = 0.152±0.002）对于淡水微藻为20 mg/L，对于海洋微藻为46 mg/L，与壳聚糖或TanFloc等其他生物基絮凝剂相当。
