No abstract

As COVID-19 and other infectious diseases continue to spread globally, removing airborne pathogens from confined spaces such as buildings, transportation carriers, and stations is becoming increasingly crucial to curbing transmission and reducing human infection rates. Bioaerosols can act as vectors or media that could store and transport air pollutants and pathogens. To mitigate the adverse effects of bioaerosols and effectively control epidemics, this work reviews the current state-ofthe-art air purification processes and technologies available on the market or demonstrated in laboratory and industrial settings, including ozone oxidation, UV disinfection, and photocatalysis. These reactive air purification processes can be used in conjunction with adsorption or filtration-based systems to enhance disinfection besides the physical capture of particulates or the removal of volatile organic compounds (VOCs). This review aims to provide a concise yet comprehensive overview of various reactive air purification technologies. Their principles, applications, and limitations are briefly discussed to provide insight and guidelines for further development of new air purification processes to address emerging airborne contaminant issues.

Pre-irradiation method was applied to graft acrylonitrile (AN) onto non-woven polyethylene film. Graft yield reached 130% at 70 kGy radiation dose, 60% monomer concentration and 4 h reaction time when H 2 SO 4 was used as an additive. The modification of AN grafted films with hydroxyl amine hydrochloride was done for the preparation of amidoxime adsorbent. The constructed adsorbent was characterized using FTIR, DMA and SEM. The amidoxime adsorbent was used for adsorption of Cu(II), Pb(II) and Cr(VI). Adsorption capacity was investigated under different conditions: contact time, pH and initial metal ion concentration. The optimum condition for maximum adsorption was found to be contact time 72 h and initial metal concentration 500 ppm for all the metal ions studied and pH 5.2 for Cu(II), 5.4 for Pb(II), 1.5 for Cr(VI). Kinetic adsorption data was elucidated using pseudo-first-order and pseudo-second-order equations. The equilibrium experimental data of metal adsorption matched Langmuir isotherm model. From the Langmuir equation, the monolayer saturation adsorption capacity (highest adsorption capacity) of the adsorbent was found to be 74.62 mg/g for Cu(II), 107 mg/g for Pb(II) and 156.25 mg/g for Cr(VI). The thermodynamics of metal adsorption was also investigated. Furthermore, desorption and reuse of the adsorbent film was studied. The results suggest that the adsorbent can be effective for adsorption of Cu(II), Pb(II) and Cr(VI).

Abstract Environmental pollution due to heavy metal contamination is a major environmental concern. A fully biodegradable and reusable adsorbent hydrogel for removal of heavy metal ions has been developed. The hydrogel was prepared from acrylic acid and chitosan using an irradiation method. The adsorbent was characterized using Fourier transform infrared analysis. Uptake of copper(II) and lead(II) at different contact times, pH, and metal ion concentrations was investigated by a batch method using atomic absorption spectroscopy. Kinetic adsorption data were studied using pseudo-first-order and pseudo-second-order equations. Experimental metal adsorption data were fitted with the Langmuir isotherm model. The maximum adsorption capacity of the hydrogel was found to be 192 and 171 mg/g for lead(II) and copper(II), respectively, from the Langmuir isotherm model. Reuse and desorption of the hydrogel were also successful. The adsorbent can be used to adsorb Cu(II) and Pb(II) by the column method with high removal efficiency. The data indicated that the designed hydrogel was environment friendly, regenerative, and can be used effectively for the removal of toxic heavy metal cations from wastewater for a sustainable environment.