Highlights in Interface of Wastewater Treatment by Utilizing Metal Organic Frameworks: Purification and Adsorption Kinetics

The recovery of precious metals, such as palladium (Pd), from wastewater, is an economically important field. The present study reports the application of polyglycidyl methacrylate (PGMA) macroporous spheres with diethylaminoethyl (DEAE) functional groups (PGMA−DEAE) for the adsorption of palladium ions [Pd(II)] from simulated wastewater solutions. The effects of pH, adsorption duration, and initial concentration of Pd(II) on the adsorption amount were evaluated systematically. The results revealed that within the experimental pH range, the adsorption efficiency of Pd(II) increased with increasing pH. In particular, between pH 4 and 6, the Pd(II) adsorption efficiencies were approximately 100%. At 298 K and pH ∼ 4, the adsorption capacity of PGMA−DEAE for Pd(II) was 1.22 mmol/g. The adsorption rates of PGMA−DEAE for Pd(II) were high, and the adsorption equilibrium was reached within 10 min. Ca(II), Mg(II), Co(II), Cu(II), Ni(II), and Fe(II) were selected as representative competitive adsorption metal ions. PGMA−DEAE had good separation selectivity for Pd(II) at pH 1−6 (all R Pd/Me > 30), especially at pH ∼ 4 (all R Pd/Me > 100). The SEM, TEM, EDS, TG, XRD, and XPS results indicated that in a high-acidity environment (C HCl ≥ 1 mol/L), Pd(II) was adsorbed on PGMA− DEAE through electrostatic attraction, while in a low-acidity environment (pH 1−6), Pd(II) was adsorbed on PGMA−DEAE through coordinated bonding between the Pd(II) ions and the N. PGMA−DEAE exhibited excellent stability and regeneration performance for five regeneration cycles.

Section: Introductionmentioning

confidence: 99%

Adsorption Behavior and Mechanism of Palladium on Diethylaminoethyl-Modified Polyglycidyl Methacrylate Macroporous Spheres

Wang,

2024

Standalone Highly Efficient Graphene Oxide as an Emerging Visible Light-Driven Photocatalyst and Recyclable Adsorbent for the Sustainable Removal of Organic Pollutants

Thakur,

Badoni,

Samriti

et al. 2024

Carbon-based nanostructures are promising eco-friendly multifunctional nanomaterials because of their tunable surface and optoelectronic properties for a variety of energy and environmental applications. The present study focuses on the synthesis of graphene oxide (GO) with particular emphasis on engineering its surface and optical properties for making it an excellent adsorbent as well as a visible lightactive photocatalyst. It was achieved by modifying the improved Hummers method through optimizing the synthesis parameters involved in the oxidation process. This controlled synthesis allows for systematic tailoring of structural, optical, and surface functionality, leading to improved adsorption and photocatalytic properties for the sustainable removal of organic pollutants in water treatment. Several spectroscopic and microscopic characterization techniques, such as XRD, SEM, Raman, UV−visible, FTIR, TEM, XPS, BET, etc. were employed to analyze the degree of oxidation, surface chemistry/functionalization, morphological, optical, and structural properties of the synthesized GO nanostructures. The analyses showed excellent surface functionality with surface active sites for better adsorptive removal and a tunable band gap from 2.51 to 2.76 eV exhibiting excellent natural sunlight activity (>99%) for photocatalytic removal of the organic pollutant. Various adsorption isotherms have been studied with excellent adsorption capability (Q max = 454.54 mg/g) as compared to the literature. The study introduces GO both as a proficient stand-alone (sole) nanoadsorbent as well as a nanophotocatalyst for the efficient removal of organic dye pollutants in water treatment. Additionally, the article highlights the sustainable solar light-induced green chemistry aspects of GO as an excellent recyclable adsorbent as a result of its self-cleaning ability under natural sunlight, demonstrating its potential in real eco-friendly environmental and practical applications.

Recent Advances of Metal–Organic Framework for Heavy Metal Ions Adsorption

Zhang,

Zhai,

Feng

et al. 2024

Heavy metal ion wastewater is a pressing and inescapable issue that is closely related to human health and ecological security due to its toxicity, carcinogenicity, and the unmanageable property of this type of wastewater. Metal–Organic Frameworks (MOFs) are a class of crystalline nanoporous materials with flexible designability and controllability, showing great potential in the field of adsorption and purification of heavy metals in wastewater. In this Perspective, we first discuss the harm of different heavy metal ions and briefly expound virtues of MOFs for pollutant adsorption. Then, we mainly summarize the recent advances in the construction of different metal-based MOFs (Zr-based, Zn-based, Co-based, Al-based, etc.) and their research progress in heavy metal ions adsorption. Furthermore, various types of MOF additives can often be effectively applied for heavy metal ion adsorption by functional modification or with other materials composition. Additionally, several commonly used adsorption kinetics and isotherm models are also detailed to help an in-depth understanding of the adsorption mechanism. Finally, the challenges and opportunities of MOFs for heavy metal ion adsorption are additionally discussed, and this review may provide new insight for other potential water purification applications.