Chitosan/Silica Nanocomposite Preparation from Shrimp Shell and Its Adsorption Performance for Methylene Blue

Abstract

In this study, novel chitosan/silica composites with different mass ratios were prepared by in-situ hydrolysis using chitosan (from shrimp shell) as a carrier, triblock copolymer (P123) as the structure-directing agent, and ethyl orthosilicate as a silicon source. These nanocomposites were characterized by different techniques, including the FT-IR, XRD, TGA, SEM, TEM and N2 adsorption–desorption. The results indicated that the morphology and properties of composites changed with the introduction of silica. When the CS/TEOS mass ratio was 0.0775, the CS−2/SiO2 composite displayed a coral-like three-dimensional porous structure with specific surface area of 640.37 m2/g and average pore size of 1.869 nm. The adsorption properties for methylene blue (MB) were investigated as well and the CS−2/SiO2 showed better adsorption performance. The removal rate for MB reached 94.01% with absorbents dosage of 6 g/L, initial concentration of 40 mg/L, initial pH value of 7, temperature of 35 °C, and adsorption time of 40 min. The adsorption process well fitted the Langmuir isothermal model and quasi-second-order adsorption kinetics model. The maximum adsorption capacity for MB was 13.966 mg/g based on Langmuir fitting. The surface functional groups of the composites can play an important role in the adsorption. The adsorption mechanism of CS−2/SiO2 on MB involved electrostatic interaction, hydrogen bonding and functional group complexation. In addition, the prepared chitosan/silica composites showed good reusability at six cycles, making them a promising material in the application of removing dyeing wastewater.

Factors Affecting Silica/Cellulose Nanocomposite Prepared via the Sol–Gel Technique: A Review

“…The adsorption of cellulose/silica composite was 6.241 mg/g. At higher pH values, adsorption remained relatively unchanged [40].…”

“…Higher temperatures also reduce gelation time and result in an increased number of secondary particles formed. Zhong et al examined the temperature effect on the adsorption of methylene blue on cellulose/silica hybrid [40]. They varied the temperature from 15 to 75 • C while keeping other parameters such as pH, dose, contact time, volume, and initial CMB constant.…”

Effect of Nano-Silica and Sorbitol on the Properties of Chitosan-Based Composite Films

“…Additionally, the diffraction peak located at 2θ = 10 • is recognized as the crystalline hydrate of chitosan, and the diffraction peak that appeared at 2θ = 20 • is assigned to the anhydrous crystallization of chitosan. Consequently, the hydrogen bands between the molecular chains of chitosan affect the crystallization behavior of chitosan, and the molecular conformation of chitosan has a significant effect on the crystalline form of chitosan [36,37].…”

“…The synergistic effect of physically modified nanoSiO 2 and -OH in sorbitol increases the free amino group in chitosan, which enables the double helix structure of the polysaccharide asymmetric unit of chitosan to become more unstable. The formation of an unstable architecture offers plentiful growth sites for the formation of amorphous nano-SiO 2 [36,40]. Based on the results of FIIR and XRD, it was determined that the inorganic phase in the prepared CS/sorbitol/SiO 2 films is amorphous silica [41].…”

Editorial for the Special Issue on the Environmentally Friendly Management and Treatment of Solid Waste to Approach Zero Waste City

“…With the rapid development of aquaculture and the seafood processing industry, a large amount of seafood waste is produced globally every year. In light of treating this waste, Zhong et al [11] prepared novel coral-like chitosan/silica porous composites by using in situ hydrolysis using chitosan as the carrier, triblock copolymer as the structuredirecting agent, and ethyl orthosilicate as the silicon source.…”