Adsorption Behaviors of Cationic Methylene Blue and Anionic Reactive Blue 19 Dyes onto Nano-Carbon Adsorbent Carbonized from Small Precursors

Abstract

In this work, an innovative nano-carbon material (N-CM) adsorbent was reported for exploring its adsorption behaviors toward cationic methylene blue (MB) and anionic reactive blue 19 (RB19) pollutants. The proposed N-CM was synthesized by a one-step solvothermal treatment of citric acid and zinc gluconate small precursors. N-CM consists of nanosheets that have an advantageous specific surface area, large sp2/sp3 hybridized domains, and abundant nitrogen/oxygen-containing surface functional groups. The synergistic effects of these features are conducive to the MB and RB19 adsorption. Different from anionic RB19 adsorption (79.54 mg/g) by the cooperative π-π stacking and hydrogen bonding, cationic MB adsorbed onto N-CM mainly by the electrostatic attraction at the natural pH solution (> pHpzc), with an adsorption capacity up to 118.98 mg/g. Interestingly, both MB and RB19 adsorption conformed to the pseudo-second order kinetic (R2 ≥ 0.995) and Langmuir isothermal (R2 ≥ 0.990) models, accompanied by similar maximum monolayer adsorption capacities of 120.77 and 116.01 mg/g, respectively. Their adsorption processes exhibited spontaneously endothermic characteristics. Moreover, N-CM showed superior selective capability toward MB in different mixed dye systems, with high removal efficiencies of 73–89%. These results demonstrate that the high-performance carbon adsorbent prepared from small precursors via low-temperature carbonization shows great potentials in wastewater treatment.

Effective Removal of Methylene Blue on EuVO4/g-C3N4 Mesoporous Nanosheets via Coupling Adsorption and Photocatalysis

“…The reason for this result is mainly that the initial MB concentration remained unchanged in the solution. With the increase of EVC-2 dosage, the adsorption active sites on EVC-2 were redundant and could not be fully utilized [ 39 ]. The effect of temperature on MB adsorption capacity at 10, 20, 30, and 40 °C is illustrated in Figure 5 d. The adsorption capacity was enhanced when the temperature rose from 10 to 30 °C, implying it was an endothermic process resulting from the π–π interaction between EVC-2 and MB [ 25 ].…”

Quantum and Experimental Studies on the Adsorption Efficiency of Oyster Shells Based CaO Nanoparticles (CaONPO) Toward the Removal of MethyleneBlue Dye (MBD) from Aqueous Solution

“…However, values reported byKumar et al (2020) for some adsorbents used for the removal of methylene blue showed that the adsorption capacities ranged from 0.1883 to 0.3890 while the initial rate ranged from 0.4053 to 1.0519 respectively. Elovich model has also been reportedly obeyed for the adsorption of methylene on silver carbon nanotube and zinc oxide nanoparticles(El-Khatib et al, 2019) Liang et al (2022). also reported 𝛽 = 0.132 𝑔/𝑚𝑔 for the adsorption of MBD by nanocarbon adsorbent and aligned the adsorption kinetics to fit Elovic and pseudo second-order model best.Weber Moris (W-M) intraparticle model (equation13) is appropriate for the description of the extent of involvement of diffusion to the adsorption removal of MBD dye by CaONPO(Oyelude et al, 2017)…”

Use of Euphorbia balsamifera Extract in Precursor Fabrication of Silver Nanoparticles for Efficient Removal of Bromocresol Green and Bromophenol Blue Toxic Dyes

“…Table 2 lists the estimated adsorption coefficients. R 2 scores are the main indicators of the precision and caliber of the linear fit procedure [49,50]. The modeling precision is demonstrated by the R 2 values in Table 2, where Langmuir (R 1 2 = 0.9981, 0.9944) > Temkin (R 3 2 = 0.8370, 0.8327) > Freundlich (R 2 2 = 0.8276, 0.8276) for the BCG and BPB dyes, respectively.…”

“…The decrease in ∆G • values with temperature shows that higher temperatures favor adsorption. The positive ∆H • values imply the occurrence of endothermic adsorption processes, while the positive ∆S • values indicate random development at the Ag-NP/dye solid-solution interface [49]. Furthermore, the reduction in the ∆G • value of BCG at temperatures ranging from 288 to 298 K demonstrates that its adsorption onto Ag-NPs is promoted by rising temperature.…”