Insight into the adsorption mechanism of cationic dye onto biosorbents derived from agricultural wastes

Abstract

This study investigated the phenomenon and mechanism of adsorption of methylene green 5 (MG5) on three pristine biosorbents: golden shower pod (GS), coconut shell (CC), and orange peel (OP). The results showed that the biosorbents possessed low specific surface areas, but abundant functional groups. Adsorption was strongly affected by the solution's pH and ionic strength. As revealed in the kinetic study, equilibrium was rapidly established, requiring low activation energies; a removal rate of 30%-87% was achieved within 1 min. The maximum Langmuir adsorption capacities at 30 °C exhibited the following order: GS (106 mg/g) > OP (92 mg/g) > CC (59 mg/g). Thermodynamic experiments suggested that the adsorption occurred spontaneously (-ΔG°) and exothermically (-ΔH°). The primary adsorption mechanisms involved electrostatic attraction, hydrogen bonding formations, and n-π interaction. Thermogravimetric analysis revealed that three biopolymer components (i.e., hemicellulose, cellulose, and lignin) played controlling roles in the adsorption process. Thus, these three agricultural residues can be considered potential low-cost adsorbents for efficient dye adsorption applications.

Insight into the adsorption mechanisms of methylene blue and chromium(iii) from aqueous solution onto pomelo fruit peel

“…One explanation is that there is a screening effect (known as the electrostatic screening) existed between the positively charged surface of pomelo fruit peel and MB molecules or Cr(III) ions. This nding is consistent with the those reported by Salazar-Rabago et al and Tran et al 3,49 Moreover, these data might suggest that the electrostatic force plays an instrumental role in the adsorption mechanism considered in the present study.…”

“…The possible mechanisms of cationic MB adsorption onto pomelo fruit peel are as follows: (1) electrostatic attraction, (2) hydrogen bonding and (3) n-p interactions; 49 whereas those of Cr(III) uptake onto this material are: (1) electrostatic attraction and (2) n-p interactions. The electrostatic attraction mechanisms can be explained based on the interaction between cationic MB and Cr(III) and negatively charged sites on the surface of pomelo fruit peel when pH solution > pH PZC .…”

Hydrothermal Carbonization of Argan Nut Shell: Functional Mesoporous Carbon with Excellent Performance in the Adsorption of Bisphenol A and Diuron

“…Sevilla and Fuertes [42], clarified that the development of the carbon material through the hydrothermal carbonization of glucose is credited to numerous responses (dehydration, polymerization, and aromatization). Fundamentally, each hydrochar frequently comprises of two sections: a hydrophobic center and a hydrophilic shell [43]. The HTC@ANS-180 and HTC@ANS-200 are obviously micrometer-sized spheres.…”

Thermally treated aluminium waste-filings, a low cost and efficient adsorbent for phosphorus removal from water

“…Goodness-of-fit evaluation of experimental data with the models was checked by non-linear regression analysis, and chi-square test, using the following equations (Tran et al, 2017a, Hosseini-Bandegharaei et al, 2016a. where qexp is the experimental value of the adsorption capacity (mg g -1 ), qcal is the calculated of the adsorption capacity from model (mg g -1 ) after using the Solver add-in in Excel software, qmean is the average of the experimental adsorption capacity (mg g -1 ), and N is the number of measurements made.…”