Efficient and Selective Adsorption of Cationic Dye Malachite Green by Kiwi-Peel-Based Biosorbents

Abstract

In this study, pristine kiwi peel (KP) and nitric acid modified kiwi peel (NA-KP) based adsorbents were prepared and evaluated for selective removal of cationic dye. The morphology and chemical structure of KP and NA-KP were fully characterized and compared, and results showed nitric acid modification introduced more functional groups. Moreover, the adsorption kinetics and isotherms of malachite green (MG) by KP and NA-KP were investigated and discussed. The results showed that the adsorption process of MG onto KP followed a pseudo-second-order kinetic model and the Langmuir isotherm model, while the adsorption process of MG onto NA-KP followed a pseudo-first-order kinetic model and the Freundlich isotherm model. Notably, the Langmuir maximum adsorption capacity of NA-KP was 580.61 mg g−1, which was superior to that of KP (297.15 mg g−1). Furthermore, thermodynamic studies demonstrated the feasible, spontaneous, and endothermic nature of the adsorption process of MG by NA-KP. Importantly, NA-KP showed superior selectivity to KP towards cationic dye MG against anionic dye methyl orange (MO). When the molar ratio of MG/MO was 1:1, the separation factor (αMG/MO) of NA-KP was 698.10, which was 5.93 times of KP. In addition, hydrogen bonding, π-π interactions, and electrostatic interaction played important roles during the MG adsorption process by NA-KP. This work provided a low-cost, eco-friendly, and efficient option for the selective removal of cationic dye from dyeing wastewater.

Comparison of Modified Peels: Natural Peels or Peels-Based Activated Carbons for the Removal of Several Pollutants Found in Wastewaters

“…Recently, pristine kiwi peel (KP) and nitric acid-modified kiwi peel (NA-KP) were produced as adsorbents and examined for the removal of cationic dyes from wastewater [30] as malachite green (MG). According to the results, the adsorption process of MG onto both KP and NA-KP fit better to the pseudo-second-order kinetic model, but according to isotherms, the adsorption onto KP followed the Langmuir model, while the adsorption process of MG onto NA-KP followed the Freundlich isotherm model.…”

“…Particularly, banana peels in powder form were examined as adsorbents for removing MB dye and pesticides, such as glyphosate and atrazine [28], or chlorpyrifos by lemon peels [29], from water. In addition, other kind of peels, such as orange, pomegranate, kiwi, etc., have been found to be effective for removing several dyes from wastewaters [30,31] and pharmaceuticals [32]. In recent literature, Artocarpus genus fruit peels were also examined as raw peels or as biomass for activated carbon production for the removal of various pollutants present in aqueous streams [33].…”

Adsorption of malachite green from aqueous phase by tea stalk powder: Parameters, kinetic, isothermal, and thermodynamic studies

“…Therefore, most agricultural wastes belong to lignocellulosic and have development potential for dye removal. Zhao et al (2023) used kiwi peel as a biosorbent for the removal of MG. Their experimental results revealed a larger amount of -NO2 and C-N functional groups on the surface of kiwi peels, and the maximum capacity of MG was reported as 580.61 mg/g based on Langmuir model simulation (Zhao et al 2023). Alene and co-workers (2021) prepared the modified adsorbent by a physicochemical activation process from Gibto (Lupinus albus) seed peel waste.…”

Catalysis in Energy and the Environment: Opportunities and Challenges

“…In addition, carbon-based composites are employed for lithium-ion batteries [14][15][16]. This Special Issue also includes investigations related to pollutant removal with sorption capability [17][18][19][20][21][22][23]. The preparation and adsorption performance of activated carbon are emphatically discussed [19,20].…”