Leão Sofia, Magalhães Solange, Alves Luís, Gamelas José A F, Lima Claudio, Stein Bruno, Rasteiro Maria da Graça
CIEPQPF, Department of Chemical Engineering, University of Coimbra, Pólo II - R. Silvio Lima, 3030-790, Coimbra, Portugal.
University of São Paulo, "Luiz de Queiroz" College of Agriculture, Agri-Food Industry and Nutrition Department, Hugot Sugar Technology Laboratory, 13418-900, Piracicaba, SP, Brazil.
Heliyon. 2023 Jun 9;9(6):e17134. doi: 10.1016/j.heliyon.2023.e17134. eCollection 2023 Jun.
In sugar production, polyacrylamide-based anionic flocculants are added for juice treatment, the main objective being to remove impurities that affect the quality of the sugar. However, if they remain in the final product, those polymers can present carcinogenic and neurotoxic actions besides contaminating the soils where the waste is discharged. To overcome this problem, the present study proposes, for the first time, natural flocculants based on cellulose obtained from sugarcane bagasse (residue from sugarcane processing) as substitutes for the flocculants based on polyacrylamide, normally used in sugar cane juice purification. Additionally, cellulose-based flocculants obtained from Acacia wood, developed in a previous study, have also been tested for sugar juice treatment. Acacia wood and sugarcane bagasse were first treated with a choline chloride/levulinic acid solution in a molar ratio of 1:2, at 160 °C, for 4 h. Subsequently, the cellulose-rich samples were modified by a two-stage process (oxidation with sodium periodate followed by reaction with sodium metabisulfite), and polyelectrolytes with different characteristics were produced. The final products obtained were characterized, and their performance in the treatment of sugarcane juice, at different concentrations (10, 50, 100, 250, and 500 mg kg), was evaluated and compared to the synthetic commercial flocculant (Flonex, based on polyacrylamide) usually used by the sugarcane industry in Brazil. The substitution of petrol-based flocculants by natural-based ones, obtained from sugarcane residues, is presented for the first time in this study, with very relevant performance of the new flocculants. Overall, it was possible to produce anionic flocculants, modifying the cellulose obtained from different raw materials, which showed good results in the purification of sucrose, when compared with the commercial polyacrylamide normally used. It is also important to stress that, for the first time, a residue from sugarcane industry could be used with success in the purification of the sugar juice itself, which constitutes a major novelty.
在制糖过程中，会添加基于聚丙烯酰胺的阴离子絮凝剂来处理蔗汁，主要目的是去除影响糖品质的杂质。然而，如果这些聚合物残留在最终产品中，除了会污染废物排放地的土壤外，还可能具有致癌和神经毒性作用。为克服这一问题，本研究首次提出以甘蔗渣（甘蔗加工后的残渣）中提取的纤维素为基础的天然絮凝剂，来替代甘蔗汁净化中常用的基于聚丙烯酰胺的絮凝剂。此外，在之前的一项研究中开发的从相思木中提取的纤维素基絮凝剂，也已用于蔗汁处理测试。相思木和甘蔗渣首先用摩尔比为1:2的氯化胆碱/乙酰丙酸溶液在160℃下处理4小时。随后，通过两步法（先用高碘酸钠氧化，再与焦亚硫酸钠反应）对富含纤维素的样品进行改性，制备出具有不同特性的聚电解质。对所得最终产品进行了表征，并评估了它们在不同浓度（10、50、100、250和500毫克/千克）下处理甘蔗汁的性能，并与巴西甘蔗行业通常使用的合成商业絮凝剂（基于聚丙烯酰胺的Flonex）进行了比较。本研究首次提出用从甘蔗残渣中获得的天然基絮凝剂替代石油基絮凝剂，新絮凝剂具有非常显著的性能。总体而言，通过改性从不同原料中获得的纤维素，可以制备出阴离子絮凝剂，与通常使用的商业聚丙烯酰胺相比，这些絮凝剂在蔗糖净化方面显示出良好的效果。同样重要的是要强调，甘蔗行业的一种残渣首次成功用于蔗汁自身的净化，这是一个重大的创新。
