Trung, Trang Si, Phuong, Pham Thi Dan, Minh, Nguyen Cong, Thuong, Nguyen Thi Nhu, Prinyawiwatkul, Witoon, Bao, Huynh Nguyen Duy, and Van Hoa, Nguyen
Chitosan lactate (CSS) has been widely used for academic and industrial applications due to its biocompatibility, biodegradability, and high biological activity. Unlike chitosan, which is generally soluble only in acid solution, CSS can be directly used by dissolving in water. In this study, CSS was prepared from moulted shrimp chitosan at room temperature by a solid-state method. Chitosan was first swollen in a mixture of ethanol and water, making it more susceptible to reacting with lactic acid in the next step. As a result, the prepared CSS had a high solubility (over 99 %) and zeta potential (+ 99.3 mV) and was comparable to the commercial product. The preparation method of CSS is facile and efficient for a large-scale process. In addition, the prepared product exhibited a potential flocculant for harvesting Nannochloropsis sp., a marine microalga widely used as a popular food for larvae. In the best condition, the CSS solution (250 ppm) at pH 10 showed the highest recovery capacity (∼ 90 % after 120 min) for harvesting Nannochloropsis sp. Besides, the harvested microalgal biomass showed excellent regeneration after 6 culture days. This paper's findings suggest a circular economy in aquaculture by producing value-added products from solid wastes, which can minimize the environmental impact and move towards sustainable zero-waste. [Display omitted] • Chitosan lactate was prepared from moulted shrimp chitosan in a solid state. • The chitosan salt had a high purity and high solubility. • The product is exhibited as a potential flocculant for harvesting microalgae. • This paper's findings suggest a circular economy in aquaculture. [ABSTRACT FROM AUTHOR]