Adsorption of methyl orange dye by SiO2 mesoporous nanoparticles: adsorption kinetics and eco-toxicity assessment in Zea mays sprout and Artemia salina

Valorizing date palm spikelets into activated carbon-derived composite for methyl orange adsorption: advancing circular bioeconomy in wastewater treatment-a comprehensive study on its equilibrium, kinetics, thermodynamics, and mechanisms

Leveraging date palm spikelets (DPS) as a precursor, this study developed a DPS-derived composite (ZnO@DPS-AC) for water treatment, focusing on methyl orange (MO) removal. The composite was synthesized through ZnCl2 activation and pyrolysis at 600 °C. Comprehensive characterization was conducted using TGA, FTIR, XRD, SEM/EDS, and pHPZC. Characterization revealed a highly carbonaceous material (> 74% carbon) with significant porosity and surface functional groups. ZnO@DPS-AC demonstrated rapid MO removal, achieving over 45% reduction within 10 min and up to 99% efficiency under optimized conditions. The Langmuir model-calculated maximum adsorption capacity reached 226.81 mg/g at 20 °C. Adsorption mechanisms involved hydrogen bonding, π-π interactions, and pore filling. The composite showed effectiveness in treating real wastewater and removing other pollutants. This study highlights the potential of agricultural waste valorization in developing efficient, sustainable adsorbents for water remediation, contributing to circular bioeconomy principles.

Effective Removal of Carcinogenic Azo Dye from Water Using Zea mays-Derived Mesoporous Activated Carbon

Addressing industrial wastewater treatment challenges and removing hazardous organic pollutants, such as carcinogenic methyl orange (MO) and azo dyes, is a pressing concern. This study explores the use of the Zea mays envelope, an agricultural waste product, to produce Z. mays activated carbon (ZMAC) through the chemical activation of maize envelopes with phosphoric acid. Various analytical techniques, including FTIR, XRD, TGA, DSC, and SEM, characterize ZMAC. Results show that ZMAC exhibits an impressive monolayer adsorption capacity of 66.2 mg/g for MO. The Langmuir isotherm model fits the experimental data well, indicating monolayer coverage of the MO on the ZMAC surface. The pH-sensitive adsorption process demonstrates an optimal removal efficiency at pH 4. ZMAC follows the pseudo-second-order kinetic model, and diffusion rate constant analysis identifies three consecutive stages in the adsorption process. Moreover, the uptake of MO ions by ZMAC is identified as an exothermic and spontaneous process. Reusability tests demonstrate efficient regeneration of ZMAC up to five times with 1 mL of 2 M HNO3 in each cycle, without sorbent mass loss. Thermodynamic analysis shows an increase in the uptake capacity from 66.2 to 73.2 mg/g with temperature elevation. This study offers practical solutions for industrial wastewater treatment challenges, providing an environmentally sustainable and effective approach to mitigate the risks associated with hazardous organic pollutants.

Harnessing the Chemical Functionality of Metal-Organic Frameworks Toward Removal of Aqueous Pollutants

Wastewater treatment has been bestowed with a plethora of materials; among them, metal-organic frameworks (MOFs) are one such kind with exceptional properties. Besides their application in gas adsorption and storage, they are applied in many fields. In orientation toward wastewater treatment, MOFs have been and are being successfully employed to capture a variety of aqueous pollutants, including both organic and inorganic ones. This review sheds light on the postsynthetic modifications (PSMs) performed over MOFs to adsorb and degrade recalcitrant. Modifications performed on the metal nodes and the linkers have been explained with reference to some widely used chemical modifications like alkylation, amination, thiol addition, tandem modifications, and coordinate modifications. The boost in pollutant removal efficacy, reaction rate, adsorption capacity, and selectivity for the modified MOFs is highlighted. The rationale and the robustness of micromotor MOFs, i.e., MOFs with motor activity, and their potential application in the capture of toxic pollutants are also presented for readers. This review also discusses the challenges and future recommendations to be considered in performing PSM over a MOF concerning wastewater treatment.