Carbon nanoadsorbents have attracted tremendous interest for metal ion removal from wastewater due to their extraordinary aspect ratios, surface areas, porosities, and reactivities. However, challenges still exist as they suffer from subpar dispersion and recovery, tending to aggregate, and so on. Thus, significant research efforts focus on modification of these carbon nanomaterials to increase the dispersions and recoveries, while maintaining or even enhancing the desirable properties. This review aims to give an in-depth look at recent and impactful advances in metal ion adsorption applications involving these modified carbon nanostructures. Here, the advanced design and testing of modified carbon nanostructures for metal ion removal are emphasized with comprehensive examples, and various adsorption behaviors and mechanisms are discussed, which are hoped to help the development of more effective adsorbents for water treatment.
A microwave reaction to convert 99 ± 1% of Ag+ to silver nanoparticles (AgNPs) of size <10 nm within 4.5 min with a specific production rate and energy input of 5.75 mg AgNP L−1 min−1 and 5.45 W mL−1 reaction volume was developed. The glucose reduced and food grade starch stabilized particles remained colloidally stable with less than a 4% change in the surface plasmon resonance band at 425–430 nm at t > 300 days. TEM determined the size of AgNPs, while TEM-EDS and XRD verified elemental composition. The conversion was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and thermal gravimetric analysis (TGA). Additionally, the required silver to starch input mass ratio, 1.0:1.3, to produce colloidally stabilized AgNPs is significantly reduced compared to previous studies. The antibacterial activity of freshly prepared AgNPs and AgNPs aged >300 days was demonstrated against E. coli as determined by agar diffusion assays. This result, corroborated by spectrophotometric and TEM measurements, indicates long-term colloidal stability of the product. Thus, this study sustainably produced antibacterial AgNPs from minimal inputs. In the broader context, the current work has quantified a sustainable platform technology to produce sphere-like inorganic nanoparticles with antimicrobial properties.
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