Extraction and Characterization of Litopenaeus vannamei’s Shell as Potential Sources of Chitosan Biopolymers

Chitin is the second most abundant polysaccharide,produced mainly as an industrial waste stream during crustacean processing.Chitin can be derived into chitosan through the deacetylation process.Conversion of shrimp waste into chitosan via the deacetylation process could be considered a practical approach for shell waste remediation.In this study,chitosan’s physicochemical characteristics extracted from two types of Pacific white leg shrimp,L.vannamei’s shell(i.e.,rough and smooth),were compared with commercial chitosan.The yield,moisture,ash,solubility,water and fat binding capacity were measured.The degree of deacetylation(DDA)was calculated using FTIR,and their chemical Structure was confirmed using XRD and SEM-EDS.Both extracted chitosan showed no significant difference in yield,moisture,ash,solubility and water binding capacity but showed a significant difference with commercial chitosan.Moreover,the fat binding capacity of commercial chitosan showed the lowest percentage(408.34±0.83%)as compared to extracted chitosan(smooth shell 549.59±12.48%;rough shell 500.55±12.10%).The DDA indicated that extracted chitosan from the smooth and rough shell was considered good chitosan as compared to commercial chitosan with 84.08±1.27%,80.78±0.79%and 74.99±1.48%,respectively.Additionally,the presence of hydroxyl and amino groups from FTIR and a good crystallinity index was recorded using XRD of extracted chitosan.Based on observed characteristics,shrimp shell waste from L.vannamei can achieve chitosan standard quality as a biopolymer and highly potential to be applied in various industrial applications.

Single Cu atom dispersed on S,N-codoped nanocarbon derived from shrimp shells for highly-efficient oxygen reduction reaction

Recently,Cu-based single-atom catalysts(SACs)have garnered increasing attention as substitutes for platinum-based catalysts in the oxygen reduction reaction(ORR).Therefore,a facile,economical,and efficient synthetic methodology for the preparation of a high-performance Cu-based SAC electrocatalyst for the ORR is extremely desired,but is also significantly challenging.In this study,we propose a ball-milling method to synthesize isolated metal SACs embedded in S,N-codoped nanocarbon(MNSDC,M=Cu,Fe,Co,Ni,Mn,Pt,and Pd).In particular,the Cu-NSDC SACs exhibit high electrochemical activity for the ORR with half-wave potential(E_(1/2))of 0.84 V(vs.reversible hydrogen electrode(RHE),20 mV higher than Pt/C)in alkaline electrolyte,excellent stability,and electrocatalytic selectivity.Density functional theory(DFT)calculations demonstrated that the desorption of OH*intermediates was the rate-determining step over Cu-NSDC.This study creates a pathway for high-performance ORR single atomic electrocatalysts for fuel cell applications and provides opportunities to convert biowaste materials into commercial opportunities.