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This study aimed to use the organic polymer, chitosan, as a flocculant for harvesting microalgae Chlorella. sp. Various polymer concentrations were tested. Within three min, 50 mg/L of chitosan showed the highest efficiency (98.9±0.5%), at pH 6.3, while the lowest efficiency (86.7±0.5%) was observed at pH 7.5. Harvesting efficiency in this study was chitosan concentration dependent. The present study showed that chitosan can be a promising and sustainable solution as an organic source and environmentally friendly flocculant. Additionally, it has excellent harvest productivity and requires minimum effort for quick outcomes. [ABSTRACT FROM AUTHOR]

Abstract The present study focuses on biopolymer surface modification of cp-Titanium with Chitosan, Gelatin, and Sodium Alginate. The biopolymers were spin coated onto a cp-Titanium substrate and further subjected to Electrochemical Impedance Spectroscopic (EIS) characterization. Artificial Neural Network (ANN) was developed to predict the Open Circuit Potential (OCP) values and Nyquist plot for bare and biopolymer coated cp-Titanium substrate. The experimental data obtained was utilized for ANN training. Two input parameters, i.e., substrate condition (coated or uncoated) and time period were considered to predict the OCP values. Backpropagation Levenberg-Marquardt training algorithm was utilized in order to train ANN and to fit the model. For Nyquist plot, the network was trained to predict the imaginary impedance based on real impedance as a function of immersion periods using the Back Propagation Bayesian algorithm. The biopolymer coated cp-Titanium substrate shows the enhanced corrosion resistance compared to uncoated substrates. The ANN model exhibits excellent comparison with the experimental results in both the cases indicating that the developed model is very accurate and efficiently predicts the OCP values and Nyquist plot. Graphical abstract Unlabelled Image Highlights • The present study focuses on evaluation of corrosion behaviour of uncoated and biopolymer coated commercially pure (CP) Ti. • Three biopolymers, i.e. , Chitosan, Gelatin B and Sodium Alginate were coated via. spin coating technique. • Open Circuit Potential (OCP) and Electrochemical Impedance spectroscopy (EIS) studies were carried out for corrosion evaluation. • Artificial Neural Network (ANN) modeling is carried out to predict OCP values and Nyquist plots. • The present ANN model can be used to predict OCP values and Nyquist plots accurately. [ABSTRACT FROM AUTHOR]

This paper investigates the enhancement of fly ash-based geopolymer with chitosan biopolymer. Unconfined compression and split tensile tests were carried out to investigate the effect of addition of small amount of N-carboxymethyl chitosan (0.05, 0.1, 0.15, and 0.2 wt% of fly ash) on the mechanical performance of fly ash-based geopolymer. Scanning electron microscopy (SEM) imaging was also conducted to study the microstructure of the chitosan enhanced fly ash-based geopolymer. The results indicated that the inclusion of N-carboxymethyl chitosan led to slight increase of the unconfined compressive strength and substantial increase of the tensile strength, the displacement at the peak tensile load and the pre-peak toughness, with the maximum increases at 0.1 wt% chitosan content. The SEM imaging indicated that the added N-carboxymethyl chitosan biopolymer coated and bridged the (geopolymerized) fly ash particles and led to the formation of a more condensed geopolymer network structure, thus enhancing the mechanical behavior of the geopolymer-biopolymer composite. However, when too much N-carboxymethyl chitosan was used, the excessive coating and encapsulation of un-reacted and partially hydrolyzed fly ash particles hindered their geopolymerization and adversely affected the mechanical behavior of the geopolymer-biopolymer composite. [ABSTRACT FROM AUTHOR]