Adsorption of Indigo Carmine onto Chemically Activated Carbons Derived from the Cameroonian Agricultural Waste Garcinia cola Nut Shells and Desorption Studies

Abstract

In the quest for a sustainable environment and clean water resources, the efficacy of activated carbons synthesized from Garcinia cola nut shells impregnated with KOH (CBK1/1) and ZnCl2 (CBZ1/1) for the adsorption of indigo carmine (IC) dye was studied using the batch technique. The prepared activated carbons were characterized using iodine number, elemental analysis, scanning electron microscopy (SEM), FTIR spectroscopy, powder X-ray diffraction (XRD), TGA/DTA, Boehm titration, and pH at point of zero charge. The elemental analysis showed a high percentage of carbon in both activated carbons (ACs). FTIR and Boehm titration analysis indicated the presence of several functional groups on the surfaces of both ACs which could influence the adsorption of IC. The primary adsorption mechanisms involved electrostatic interaction, hydrogen bonds formation, and π−π interactions. Maximum adsorption capacity values obtained using the Fritz–Schlunder III three-parameter model were 19.019 mg·g−1 and 18.299 mg·g−1 for CBK1/1 and CBZ1/1, respectively. The Fritz–Schlunder model exponent mFS of value less than 1 showed that the adsorption of IC by the ACs occurred on heterogeneous surfaces. Positive values of ∆Q obtained by the linear and nonlinear forms of the Temkin model indicate the exothermic character of the adsorption process.

The efficiency of Raphia hookeri adsorbent in indigo carmine dye removal: Economy depth via chemometrics

“…The electrostatic repulsion force between indigo carmine and the adsorbent causes a decrease in adsorption capacity. Similar findings have been reported [ 59 , 60 ].

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The Influence of Solution Concentration and pH for Removal Indigo Carmine using Banana Stem as a Biosorbent

“…There are more proton ions available to help H + ions become positively charged on the biosorbent's surface in BP at pH <pHpzc, which can enhance the electrostatic interaction between the negatively charged indigo carmine dye and the positively charged biosorbent site. Moreover, two aromatic rings and two sulfonic acid groups give indigo carmine dye its great removal effectiveness at low pH (Kuete et al, 2022). Harrache (2019) reported the same results in a study that used activated carbon to find the best pH 2 adsorption of indigo carmine dye (Harrache et al, 2019).…”

Optimized preparation of activated carbon with high porosities based on puck shells ( Afrostyrax lepidophyllus ) by response surface methodology and physico-chemical characterization

“…The diffraction patterns of the two ACs have the same shape and show similar peaks at 2 θ = 22° and 2 θ = 42° which are attributed, respectively, to the presence of carbon and dehydrated hemicellulose [32,33]. We can also note the presence of the background noise signals corresponding to the ACs powder, thus revealing an absence of crystallinity and therefore an amorphous structure of the ACs which is an advantageous property for well-defined porous adsorbent [34]. This can be explained by the fact that subjection of CRN to high temperatures contributed to the breaking of the chemical bonds [35].…”