Novel ZIF-8/CNC Nanohybrid with an Interconnected Structure: Toward a Sustainable Adsorbent for Efficient Removal of Cd(II) Ions

Abstract

Water pollution, especially by heavy metals, continues to pose significant challenges, emphasizing the urgency to develop sustainable processes to remove pollutants while developing sustainable materials derived from renewable sources. In the present research, a nanoscale adsorbent was prepared to remove cadmium (Cd(II)) ions from wastewater by hybridizing zeolitic imidazolate framework-8 (ZIF-8) with a cellulose nanocrystal (CNC). The prepared nanohybrid exhibited an interconnected structure in which the ZIF-8 particles were connected to each other via CNC nanoneedles. The hybridization of ZIF-8 with CNC caused a significant enhancement in the adsorption performance of the fabricated nanohybrid compared to pure ZIF-8, increasing its adsorption capacity by nearly 36%. The adsorption of ZIF/CNC followed the Langmuir isotherm model and pseudo-second-order kinetics models, remarking homogeneous adsorption onto the surface of ZIF/CNC, where chemisorption controlled the rate of adsorption. The thermodynamic study uncovered that the adsorption is spontaneous, endothermic, and entropy-governed as the randomness was increased at the solid–liquid interface. Additionally, the influence of operating variables, such as temperature, adsorbent dosage, pH, and ionic strength, was studied to mimic the adsorption capabilities of the adsorbent in real conditions. Accordingly, the optimum conditions were found to be at 45 °C and pH = 7 with a dosage of 0.4 g/L for the adsorbent. Moreover, the adsorption in a multimetal solution showed that the ZIF/CNC nanohybrid can remove various heavy metals, including Cd(II), Fe(III), Cu(II), and Pb(II) ions simultaneously. Finally, the regeneration study confirmed the great potential of the ZIF/CNC nanohybrid, which retained 94% of its initial adsorption capacity after 5 consecutive adsorption/desorption cycles.

Liquid Metal Nanoparticles Physically Hybridized with Cellulose Nanocrystals Initiate and Toughen Hydrogels with Piezoionic Properties

“…Morphological analysis of microstructures/nanoparticles within the hydrogel network was done using Cryo-SEM (JEOL with a Gatan cryo system). The morphology of LM-CNC particles was studied using FE (field emission)-SEM (FE-SEM-MIRA3 TESCAN), functioning at 15 kV . Elemental mapping analysis on LM-CNC particles was done using energy-dispersive X-ray analysis (EDAX)-SEM.…”

ZIF‐8 Composites for the Removal of Wastewater Pollutants

“…[40] ZIF-8/CNC composite maintain crystalline structure after the adsorption and 5 regeneration cycles. [41]…”

Fe3O4/Graphene Oxide/Chitosan Nanocomposite: A Smart Nanosorbent for Lead(II) Ion Removal from Contaminated Water

“…Along with technological advancement, toxic metal contamination has become a severe problem that threatens human health . Lead, mercury, chromium, arsenic, cadmium, zinc, copper, and nickel are the most common contaminants found in contaminated surface water, groundwater, and industrial wastewater. − Exposure to heavy metals imparts serious threats to the ecosphere and human health owing to their high toxicity, nonbiodegradability, and environmental persistence . As a ubiquitous and priority pollutant categorized by the US Environmental Protection Agency (USEPA), Pb­(II) is primarily discharged from various sources, including mining, battery and metallurgical manufacturing, printing and painting industries, and smelting operations. − The World Health Organization and the US Environmental Protection Agency have set the permissible limit of Pb­(II) concentration in drinking water to be 0.01 and 0.015 mg L –1 .…”