Synergistic removal of Cu(II) and nitrazine yellow dye using an eco‐friendly chitosan‐montmorillonite hydrogel: Optimization by response surface methodology

Abstract

A comprehensive feasibility study on adsorption of Cu(II) and a water‐soluble nitrazine yellow (NY) dye by chitosan‐montmorillonite (CS‐MMT) hydrogel as the biosorbent was investigated as a function of biosorbent dosage, initial concentration, pH, temperature, and the presence of salts. Box–Behnken methodology was applied to optimize the adsorption experiments. Maximum adsorption values were determined as 132.74 mg/g and 144.41 mg/g at pH = 5.0, for Cu(II) and NY dye, respectively. Equilibrium isotherms of Langmuir and Freundlich were analyzed by the non‐linear regression model. The equilibrium data were well described by Freundlich model and the adsorption process well fitted pseudo‐second order kinetics. The enthalpy change of adsorption (ΔH°) were calculated as −3.78 kJ/mol and −5.75 kJ/mol for Cu(II) and NY dye, respectively, indicating that the adsorption processes were exothermic. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43664.

Removal of Cd2+ ions from aqueous solution using cassava starch–based superabsorbent polymers

“…As Ngwabebhoh et al . discussed, the observed enhanced and broadened bands for CST‐SAP‐Cd 2+ were attributed to the binding of heavy metal to amide and hydroxyl groups of the CST‐SAP hydrogel …”

“…The Freundlich isotherm explains the adsorption on a heterogeneous (multilayer) surface with a uniform energy distribution . The Freundlich equation is where K F is the Freundlich constant related to the adsorption capacity (mg/g), and n indicates the heterogeneity coefficient (dimensionless).…”

“…The residual Cd 2+ ion concentration in the filtrate was measured by atomic absorption spectrometry (AAS‐5000, Germany). The equilibrium adsorption capacity ( Q e ) and the removal percentage (%) of the CST‐SAPs were calculated using the following equations: where C 0 (µg/mL) and V 0 (mL) are the initial content and volume of metal ion, respectively; C e (µg/mL) and V e (mL) are the equilibrium content and volume; m 0 (g) is the mass of the biosorbent; Q e (mg/g) is the equilibrium adsorption capacity of the metal ion; and % R is the percentage removal …”

Photoinitiated synthesis of poly(poly(ethylene glycol) methacrylate‐co‐diethyl amino ethyl methacrylate) superabsorbent hydrogels for dye adsorption

“…The adsorption equilibrium data were analyzed by Langmuir, Freundlich, and Temkin isotherms linear models : where C e is the equilibrium adsorbate concentration (mg L −1 ), q max is the monolayer maximum adsorption capacity (mg g −1 ), K L is the Langmuir adsorption constant (L mg −1 ) related to the free energy of adsorption, K F the adsorption capacity, n is adsorption intensity (how favorable is the adsorption process). K T is the equilibrium binding constant (L mg −1 ), b T is Temkin constant, R is the gas constant (J K −1 mol −1 ), and T is the room temperature (K).…”

Effective removal of a cobalt‐tetrasulfonated phthalocyanine dye from an aqueous solution with a novel modified chitosan‐based superabsorbent hydrogel

“…Chitosan has been widely investigated as a biosorbent for the capture of pollutants, including metals, dyes, phenols, ammonium nitrogen, nitrate, fluoride, and phthalates, from wastewater. In particular, hydrogels obtained from chitosan have spurred great interest in the adsorption of dyes from aqueous solutions because of their internal porous structure, ecofriendliness, cost‐effectiveness, and high specific surface area . Interestingly, the amine groups give the chitosan cationic characteristics, and the protonation of chitosan in acidic media leads to the adsorption of metal anions by ion exchange .…”