RESUMO
Two carbon composite materials were prepared by mixing avocado biochar and methyl polysiloxane (MK). Firstly, MK was dissolved in ethanol, and then the biochar was added at different times. In sample 1 (R1), the time of adding biochar was immediately after dissolving MK in ethanol, and in sample 2 (R2), after 48 h of MK dissolved in ethanol. The samples were characterized by nitrogen adsorption/desorption measurements obtaining specific surface areas (SBET) of 115 m2 g-1 (R1) and 580 m2 g-1 (R2). The adsorbents were further characterized using scanning electron microscopy, FTIR and Raman spectroscopy, adsorption of vapors of n-heptane and water, thermal analysis, Bohem titration, pHpzc, and C H N elemental analysis. R1 and R2 adsorbents were employed as adsorbents to remove the antibiotic ciprofloxacin from the waters. The t1/2 and t0.95 based on the interpolation of Avrami fractional-order were 20.52 and 246.4 min (R1) and 14.00 and 157.6 min (R2), respectively. Maximum adsorption capacities (Qmax) based on the Liu isotherm were 10.77 (R1) and 63.80 mg g-1 (R2) for ciprofloxacin. The thermodynamic studies showed a spontaneous and exothermic process for both samples, and the value of ΔH° is compatible with physical adsorption.
Assuntos
Persea , Poluentes Químicos da Água , Adsorção , Antibacterianos/química , Carbono , Carvão Vegetal/química , Ciprofloxacina/química , Etanol , Concentração de Íons de Hidrogênio , Cinética , Nitrogênio/análise , Siloxanas , Termodinâmica , Água , Poluentes Químicos da Água/análiseRESUMO
The outbreak of COVID-19 pandemic has emerged as a major challenge from human health perspective. The alarming exponential increase in the transmission and fatality rates related to this disease has brought the world to a halt so as to cope up with its stern consequences. This has led to the imposition of lockdown across the globe to prevent the further spread of this disease. This lock down brought about drastic impacts at social and economic fronts. However, it also posed some positive impacts on environment as well particularly in the context of air quality due to reduction in concentrations of particulate matter (PM), NO2 and CO across the major cities of the globe as indicated by several research organizations. In China, Italy, France and Spain, there were about 20-30% reduction in NO2 emission while in USA 30% reduction in NO2 emission were observed. Compared to previous year, there was 11.4% improvement in the air quality in China. Drastic reductions in NO (-77.3%), NO2 (-54.3%) and CO (-64.8%) (negative sign indicating a decline) concentrations were observed in Brazil during partial lockdown compared to the five year monthly mean. In India there were about -51.84, -53.11, -17.97, -52.68, -30.35, 0.78 and -12.33% reduction in the concentration of PM10, PM2.5, SO2, NO2, CO, O3 and NH3 respectively. This article highlights the impact of lockdown on the environment and also discusses the pre and post lockdown air pollution scenario across major cities of the world. Several aspect of environment such as air, water, noise pollution and waste management during, pre and post lockdown scenario were studied and evaluated comprehensively. This research would therefore serve as a guide to environmentalist, administrators and frontline warriors for fighting our the way to beat this deadly disease and minimize its long term implications on health and environment.