Preparation and Application of Efficient Biobased Carbon Adsorbents Prepared from Spruce Bark Residues for Efficient Removal of Reactive Dyes and Colors from Synthetic Effluents

Abstract

Biobased carbon materials (BBC) obtained from Norway spruce (Picea abies Karst.) bark was produced by single-step chemical activation with ZnCl2 or KOH, and pyrolysis at 800 °C for one hour. The chemical activation reagent had a significant impact on the properties of the BBCs. KOH-biobased carbon material (KOH-BBC) had a higher specific surface area (SBET), equal to 1067 m2 g−1, larger pore volume (0.558 cm3 g−1), more mesopores, and a more hydrophilic surface than ZnCl2-BBC. However, the carbon yield for KOH-BBC was 63% lower than for ZnCl2-BBC. Batch adsorption experiments were performed to evaluate the ability of the two BBCs to remove two dyes, reactive orange 16 (RO-16) and reactive blue 4 (RB-4), and treat synthetic effluents. The general order model was most suitable for modeling the adsorption kinetics of both dyes and BBCs. The equilibrium parameters at 22 °C were calculated using the Liu model. Upon adsorption of RO-16, Qmax was 90.1 mg g−1 for ZnCl2-BBC and 354.8 mg g−1 for KOH-BBC. With RB-4, Qmax was 332.9 mg g−1 for ZnCl2-BBC and 582.5 mg g−1 for KOH-BBC. Based on characterization and experimental data, it was suggested that electrostatic interactions and hydrogen bonds between BBCs and RO-16 and RB-4 dyes played the most crucial role in the adsorption process. The biobased carbon materials showed high efficiency for removing RO-16 and RB-4, comparable to the best examples from the literature. Additionally, both the KOH- and ZnCl2-BBC showed a high ability to purify two synthetic effluents, but the KOH-BBC was superior.

Process Parameters Optimization, Characterization, and Application of KOH-Activated Norway Spruce Bark Graphitic Biochars for Efficient Azo Dye Adsorption

“…The kinetic curves and fitting parameters of the models are shown in Figure 11a and Table 4. The suitability of the models was evaluated through the determination coefficient R 2 adj and standard deviation (SD) [42][43][44][45][46][47][48][49]. The general-order model is the most suitable model because it presents the highest R ² adj and lowest SD values (Table 4).…”

“…Based on the biochar's physicochemical characterization, such as SSA, pore size, FTIR, and XPS-as well as the adsorption results, such as the initial pH solution, kinetics of adsorption, and equilibrium studies-it was possible to suggest the primary mechanisms of adsorption for EB on biochar (see Figure 13). The adsorption process takes place through different physical interactions between biochar surface and EB dye such as hydrogen bonding and π-π and n-π interactions of the aromatic ring of the biochar with the aromatic rings of the EB dye [36,43,48]. Hydrogen bonding is formed with the azo groups of the dye with the hydroxyl groups present on the biochar's surface [36,43,48].…”

“…The adsorption process takes place through different physical interactions between biochar surface and EB dye such as hydrogen bonding and π-π and n-π interactions of the aromatic ring of the biochar with the aromatic rings of the EB dye [36,43,48]. Hydrogen bonding is formed with the azo groups of the dye with the hydroxyl groups present on the biochar's surface [36,43,48]. π-π and n-π interactions (donor-acceptor interactions) The adsorption process takes place through different physical interactions between biochar surface and EB dye such as hydrogen bonding and π-π and n-π interactions of the aromatic ring of the biochar with the aromatic rings of the EB dye [36,43,48].…”

“…Hydrogen bonding is formed with the azo groups of the dye with the hydroxyl groups present on the biochar's surface [36,43,48]. π-π and n-π interactions (donor-acceptor interactions) The adsorption process takes place through different physical interactions between biochar surface and EB dye such as hydrogen bonding and π-π and n-π interactions of the aromatic ring of the biochar with the aromatic rings of the EB dye [36,43,48]. Hydrogen bonding is formed with the azo groups of the dye with the hydroxyl groups present on the biochar's surface [36,43,48].…”

Special Issue “Natural Fiber Based Composites”

“…Plants can also be the source of natural adsorbents. Another research report in this Special Issue thus presents the obtaining of efficient biobased carbon adsorbents [19]. Prepared from spruce bark residues, these will find application for efficient removal of reactive dyes and colors from synthetic effluents, and may be used for treating contaminated wastewater to remove pollutants.…”