Selective heavy metal removal and water purification by microfluidically-generated chitosan microspheres: Characteristics, modeling and application

Abstract

Many industrial wastewater streams contain heavy metals, posing serious and irreversible damage to humans and living organisms, even at low concentrations due to their high toxicity and persistence in the environment. In this study, high-performance monodispersed chitosan (CS) microspheres were prepared using a simple microfluidic method and evaluated for metal removal from contaminated water. Batch experiments were carried out to evaluate the adsorption characteristics for the removal of copper ions, one representative heavy metal, from aqueous solutions. The inherent advantages of microfluidics enabled a precise control of particle size (CV=2.3%), while exhibiting outstanding selectivity towards target ions (adsorption capacity 75.52 mg g-1) and fair regeneration (re-adsorption efficiency 74% after 5 cycles). An integrated adsorption mechanism analytic system was developed based on different adsorption kinetics and isotherms models, providing an excellent adsorption prediction model with pseudo-second order kinetics (R 2 = 0.999), while the isotherm was fitted best to the Langmuir model (R 2 = 0.998). The multi-step adsorption process was revealed via quantitative measurements and schematically described. Selective adsorption performance of CS microspheres in the present of other competitive metal ions with different valence states has been demonstrated and studied by both experimental and density functional theory (DFT) analysis.

Chitin- and Chitosan-Based Derivatives in Plant Protection against Biotic and Abiotic Stresses and in Recovery of Contaminated Soil and Water

“…Novel chitosan-based nanomembranes can be used to treat industrial wastewater contaminated by chromium [46] and chitosan-based magnetic microgels for the cleaning of cesium-contaminated clay [47]. Nano-fungal chitosan removes Pb 2+ and Cu 2+ from the water and soil matrix [48], while microfluidically-generated chitosan microspheres adsorb Cu ions from industrial wastewater [49]. Sorption studies carried out on contaminated groundwater using columns packed with chitosan demonstrate the capability of these columns to remove arsenic compounds [50].…”

Hydrophilic Molecularly Imprinted Chitosan Based on Deep Eutectic Solvents for the Enrichment of Gallic Acid in Red Ginseng Tea

“…Moreover, CS is an eco-friendly and cost-effective biopolymer that can be modified easily by various chemical reactions to improve its physicochemical properties [8]. CS can be modified mainly using its amine group, by crosslinking reactions to make it insoluble in acidic pH or by grafting new functional groups to the amine and hydroxyl groups to add new chemical properties and improve the selectivity for the targets [9]. With the addition of new functional groups on CS, it is possible to increase the number of adsorption sites [10].…”

Avaliação da adsorção de cromo em carboximeticelulose obtida a partir de palha de milho modificada e ativada com diferentes líquidos iônicos

“…A isoterma de Freundlich é um outro modelo empírico comumente utilizado em estudos envolvendo processos de adsorção desenvolvido, inicialmente, para gases. O mesmo é capaz de relacionar a quantidade adsorvida de adsorvato com a concentração de adsorvato na fase tratada e pode ser aplicado para sistemas não ideais, reversíveis e, de superfícies heterogêneas (WANG et al, 2019;ZHANG et al, 2019;AMALRAJ et al, 2016).…”

“…O modelo considera o mecanismo de adsorção ocorrendo em multicamadas e, não prevê a ocupação de todos os sítios de adsorção. Assim, não ocorre saturação do material e, também, distribuição uniforme de calor de adsorção, o que caracteriza uma distribuição exponencial dos sítios de adsorção (WANG et al, 2019;RANGABHASHIYAM;BALASUBRAMANIAN, 2018;AMALRAJ et al, 2016;FAUST;ALY, 1987;SEADER;HENLEY, 1998). O mesmo pode ser descrito pela equação 7:…”

“…forma, a construção de um gráfico de C e q e ⁄ em função de C e por linearização fornecerá uma reta com coeficientes angular de 1 q máx ⁄ e, coeficiente linear de 1 K L q máx ⁄ (RANGABHASHIYAM; BALASUBRAMANIAN, 2018; FAUST; ALY, 1987).O fator de separação em processos de adsorção representa a afinidade pela fase sólida em relação a fase líquida, ou seja, quanto mais próximo de 0 for o valor de RL, mais favorável a adsorção, o que indica uma elevada afinidade do adsorvato pelo sólido adsorvente. Em contrapartida se RL for maior que 1 a adsorção é desfavorável e, o adsorvato tem uma maior afinidade com a fase fluida e, quando RL for igual a 0, a adsorção é linear(WANG et al, 2019; …”