AI Article Synopsis
- Chitosan effectively removes color from synthetic reactive dye wastewater (SRDW) in both acidic and caustic conditions, with adsorption influenced by electrostatic and covalent interactions.
- The adsorption characteristics vary with pH and temperature, showing that maximum capacities increase at higher temperatures, reaching up to 156 mg g(-1) at pH 11.0 and 60 degrees C.
- Chemical adsorption is the main mechanism under acidic conditions, while both physical and chemical adsorption are observed under caustic conditions, suggesting a spontaneous and exothermic process.
Article Abstract
Chitosan was able to remove the color from synthetic reactive dye wastewater (SRDW) under acidic and caustic conditions. The effect of the initial pH on SRDW indicated that electrostatic interaction occurred between the effective functional groups (amino groups) and the dye under acidic conditions. Moreover, SRDW adsorption under caustic conditions was also affected by the covalent bonding of dye and hydroxyl groups of chitosan. In addition, elution tests confirmed that chemical adsorption occurred under acidic conditions, while both physical and chemical adsorption appeared under caustic conditions. The spectra of attenuated total reflectance Fourier transform infrared spectrometry confirmed the functional groups of chitosan that affected the SRDW adsorption. However, the maximum adsorption capacities of chitosan increased when the temperature increased. The maximum adsorption capacity of chitosan obtained from the Langmuir model was 68, 110, and 156 mg g(-1) under a system pH of 11.0 at 20, 40, and 60 degrees C, respectively. The negative values of enthalpy change (DeltaH), free energy change (DeltaG), and entropy change (DeltaS) indicated an exothermic, spontaneous process and decreasing disorder of the system, respectively. Therefore, the mechanism of SRDW adsorption by chitosan was probably by chemical adsorption for a wide range of pH's and at high temperatures.
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| http://dx.doi.org/10.1016/j.jcis.2005.01.020 | DOI Listing |
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