The adsorption process of Eriochrome Black T (EBT) onto surface-modified zinc oxide nanoparticles is governed by a complex interplay of physicochemical interactions, which can be elucidated through kinetic modeling. This study systematically evaluated the adsorption kinetics using three models: pseudo-first-order, pseudo-second-order, and intraparticle diffusion. The experimental data revealed that the pseudo-second-order model provided the best fit, with correlation coefficients (R²) exceeding 0.98 for both CTAB@ZnO and BMTF@ZnO-NPs. This indicates that the rate-limiting step is chemisorption, involving valence forces through sharing or exchange of electrons between the dye molecules and active sites on the nanoparticle surface. The calculated equilibrium adsorption capacity (qe) from this model closely matched the experimental values—34.85 mg/g for BMTF@ZnO-NPs and 18.4 mg/g for CTAB@ZnO-NPs—further validating its accuracy. In contrast, the pseudo-first-order model yielded lower R² values (0.96–0.97), suggesting it inadequately describes the adsorption mechanism. The intraparticle diffusion model also showed high correlation (R² = 0.98), indicating that the diffusion of EBT molecules into the pores of the nanoparticles plays a significant role in the overall process. However, the presence of intercepts (Ci) greater than zero in the plots suggests that film diffusion also contributes to the rate, meaning adsorption is not solely controlled by pore diffusion. This dual-phase transport mechanism—initial rapid surface adsorption followed by slower internal diffusion—was clearly observed in the time-dependent removal curves, where maximum uptake occurred within 30 minutes. The higher initial rate for BMTF@ZnO-NPs aligns with their smaller particle size and larger surface area, facilitating faster access to internal sites. These kinetic findings confirm that the enhanced performance of modified ZnO-NPs stems not only from increased surface charge but also from improved mass transfer characteristics. Understanding these dynamics enables the rational design of more efficient adsorbents by optimizing particle size, porosity, and surface functionalization.
Environmental Application and Real-Water Performance of Modified ZnO Nanoadsorbents
The practical utility of any water treatment technology hinges on its effectiveness in real-world conditions. This study rigorously tested the adsorption capabilities of CTAB@ZnO and BMTF@ZnO nanoparticles in various real water matrices, including Sukhna Lake water, tap water, rainwater, and distilled water spiked with Eriochrome Black T (EBT). The results demonstrated remarkable resilience and consistent performance across all samples. Despite the presence of natural organic matter, dissolved ions, and other potential interferents, the removal efficiency remained above 80% in all cases, with only marginal reductions compared to synthetic solutions. Notably, the BMTF@ZnO-NPs maintained a removal rate of 87%, while CTAB@ZnO-NPs achieved 84%, confirming their robustness under complex environmental conditions. The minimal impact of co-existing ions such as Al³⁺, Cd²⁺, Na⁺, and CO₃²⁻—as evidenced by interference studies—indicates that the surface functional groups of the nanoparticles are highly selective for EBT, minimizing competition for adsorption sites. This selectivity is attributed to the strong electrostatic interaction between the anionic dye and the positively charged surface of the modified ZnO-NPs. Furthermore, the ability to operate effectively at pH 3.0, a condition commonly found in industrial effluents, enhances their suitability for direct application in wastewater treatment plants. The successful performance in real water samples validates the scalability of the system beyond laboratory settings. Unlike many reported methods that rely on idealized conditions, this work demonstrates that surface-modified ZnO-NPs can function efficiently in actual environmental scenarios, offering a promising solution for the remediation of dye-contaminated water bodies. Their compatibility with diverse water sources makes them a versatile tool for both point-source pollution control and broader ecosystem protection.
Toxicity Assessment of Adsorbed Eriochrome Black T Solutions Using Vigna radiata Seeds
A critical component of evaluating any water purification method is determining whether the treated effluent poses residual risks to living organisms. This study employed Vigna radiata seeds as a biological indicator to assess the phytotoxicity of Eriochrome Black T (EBT) solutions before and after treatment with surface-modified ZnO nanoparticles. Pure EBT solution exhibited severe toxicity, resulting in only 20% seed germination and negligible root elongation. In stark contrast, seeds exposed to solutions treated with BMTF@ZnO and CTAB@ZnO-NPs showed near-complete germination (100%) and significantly enhanced root growth. Quantitative analysis confirmed a dramatic reduction in toxicity: 98% for BMTF@ZnO-treated samples and 97.9% for CTAB@ZnO-treated samples, compared to untreated EBT. The relative root growth inhibition (RRGI) values were drastically reduced—from 0.982 for pure EBT to 0.127 and 0.173, respectively—indicating that the adsorption process effectively neutralizes the harmful effects of the dye. Biomass increment analysis further supported these findings: seeds treated with BMTF@ZnO-NP solutions gained 39.55% biomass, significantly surpassing the 14.5% gain observed in pure EBT samples. The visual comparison of seedlings over seven days revealed healthy, vigorous growth in all treated samples, with no signs of stunting or discoloration. These results demonstrate that the adsorption process does not merely remove the dye but also eliminates its toxicological impact, transforming hazardous waste into safe effluent. This comprehensive biological evaluation provides strong evidence for the environmental safety of the treated water, making the modified ZnO-NPs a reliable and responsible choice for sustainable water treatment applications.
Regeneration and Reusability Analysis of Surface-Modified Zinc Oxide Nanoparticles
Sustainable water treatment technologies must balance high efficiency with operational cost-effectiveness, which is largely determined by the reusability of the adsorbent. This study conducted a thorough investigation into the regeneration and reuse capability of CTAB@ZnO and BMTF@ZnO nanoparticles after multiple cycles of Eriochrome Black T (EBT) adsorption.111025-46-8 SMILES After each cycle, the nanoparticles were recovered via centrifugation, washed with deionized water and ethanol to remove residual dye, dried, and then reused.444805-28-1 medchemexpress The results showed exceptional stability: BMTF@ZnO-NPs retained 85% of their original adsorption capacity even after four consecutive cycles, while CTAB@ZnO-NPs maintained approximately 79%.PMID:30725882 This high retention rate confirms that the surface modifications effectively prevent structural degradation and aggregation during repeated use. To verify chemical integrity, the nanoparticles were analyzed post-reuse using FTIR and XRD spectroscopy. The FTIR spectra showed no significant changes in functional group peaks, indicating the preservation of key binding sites. XRD patterns remained unchanged, confirming the maintenance of the crystalline wurtzite structure of ZnO. These analytical results validate that the nanoparticles undergo minimal physical or chemical alteration during regeneration. Additionally, desorption experiments successfully recovered nearly the entire amount of adsorbed EBT, with spectral profiles matching those of the original dye, demonstrating the feasibility of resource recovery. The ability to regenerate and reuse the nanoadsorbents multiple times without performance loss significantly reduces material consumption and waste generation, enhancing both economic viability and environmental sustainability. This robust reusability profile positions surface-modified ZnO-NPs as a practical and scalable solution for long-term industrial wastewater treatment systems.
Mechanistic Pathway of Eriochrome Black T Adsorption on Functionalized ZnO Surfaces
The adsorption of Eriochrome Black T (EBT) onto surface-functionalized zinc oxide nanoparticles involves a multi-step mechanistic pathway driven by synergistic interactions. Initially, electrostatic attraction occurs between the negatively charged sulfonate groups (-SO₃⁻) of EBT and the positively charged surface of ZnO-NPs at pH 3.0, where the zeta potential is positive. This rapid initial adsorption is followed by a secondary phase involving coordination bonding. The nitrogen atoms in the cationic modifiers—CTAB’s quaternary ammonium group and BMTF’s imidazolium ring—act as electron donors, forming coordinate bonds with the metal centers on the ZnO surface. Simultaneously, π–π stacking interactions occur between the aromatic rings of EBT and the planar structures of the modifiers, contributing to stable surface coverage. FTIR spectroscopy provides direct evidence: the disappearance or significant shift of characteristic peaks of EBT (e.g., C=N stretch at 1336 cm⁻¹, C=O at 1200 cm⁻¹, ring bends at 795 and 740 cm⁻¹) after adsorption confirms molecular-level interaction. The shifts in the O–H and C–N stretches of the modifiers further support their involvement in the binding process. The Freundlich isotherm model (R² = 0.99) indicates multilayer adsorption on heterogeneous surfaces, facilitated by the high surface area and abundant active sites introduced by the modifiers. The pseudo-second-order kinetic model confirms chemisorption as the dominant mechanism, while intraparticle diffusion modeling reveals that mass transfer into the nanoparticle pores is a key factor influencing the rate. The proposed mechanism is thus a combination of electrostatic attraction, coordination bonding, π–π interactions, and pore diffusion. This multifaceted pathway explains the superior performance of modified ZnO-NPs over bare ZnO and provides a clear foundation for designing next-generation adsorbents with tailored functionalities for specific pollutants.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com