In the quest for innovative solutions to environmental challenges, researchers have turned to an unlikely source: the humble Moringa oleifera seed. A recent study published in *Discover Materials* (which translates to *Discover Materials* in English) reveals how modifying the seed hulls of this plant with hydroxyapatite can create a highly effective adsorbent for removing toxic dyes from wastewater. This breakthrough could have significant implications for the energy sector, particularly in the treatment of industrial effluents.
Patrick T. Ngueagni, a researcher from the Department of Inorganic Chemistry at the University of Yaoundé I, led the study. The team developed a composite material, MO@HA, by combining Moringa oleifera seed hulls with hydroxyapatite (HA). This novel adsorbent was characterized using advanced techniques such as TGA/DSC, XRD, and TEM/EDX. The results were promising: the composite exhibited excellent thermal stability, a high oxygen content, and an atomic percentage of calcium of 1.86%.
The study delved into the kinetics and thermodynamics of the adsorption process for two common dyes, Toluidine Blue (TB) and Methyl Violet 2B (MV 2B). The researchers investigated the adsorption at various concentrations (50–300 mg/L) and temperatures (293–333 K). The adsorption kinetics were analyzed using different kinetic models to determine the rate-controlling mechanisms. The results showed that the adsorption of both TB and MV 2B onto the composite adsorbent followed the pseudo-first-order model, with correlation coefficients ranging from 0.9813 to 0.9984 for TB and 0.9835 to 0.9922 for MV 2B.
“Our findings indicate that the adsorption process is highly efficient and follows a pseudo-first-order kinetic model,” Ngueagni explained. “This suggests that the rate-limiting step is the diffusion of the dye molecules to the adsorbent surface.”
The thermodynamic parameters were also evaluated to assess the spontaneity and energy changes associated with the adsorption process. The results showed that the adsorption of both dyes was feasible, spontaneous, favorable, and endothermic. For MV 2B, the Gibbs free energy (ΔG°) varied from −1.802 to -15.203 kJ mol−1, the enthalpy change (∆H°) was 96.38 kJ mol−1, and the entropy change (∆S°) was +335.02 J mol−1 K−1. For TB, the ΔG° varied from −0.941 to -13.950 kJ mol−1, the ∆H° was 94.36 kJ mol−1, and the ∆S° was +325.24 J mol−1 K−1.
The study also found that the sticking probabilities of TB and MV 2B on the surface of MO@HA were high, indicating that the adsorption process was physical in nature. This makes the composite material particularly attractive for environmental remediation applications.
The implications for the energy sector are significant. Industrial effluents often contain toxic dyes that can harm the environment and human health. Effective adsorbents like MO@HA can help in the treatment of these effluents, reducing the environmental impact and ensuring compliance with regulatory standards.
“This research opens up new possibilities for the use of Moringa oleifera seed hulls in environmental remediation,” Ngueagni said. “The functionalization of these seed hulls with hydroxyapatite significantly enhances their dye removal efficiency, making them a promising material for industrial applications.”
As the energy sector continues to grapple with the challenges of wastewater treatment, innovations like MO@HA offer a glimmer of hope. The study, published in *Discover Materials*, highlights the potential of this composite material and paves the way for further research and development in the field of environmental remediation.