Numerical and physical assessment of control measures to mitigate fugitive dust emissions from harbor activities

In recent years, the industrial demand for petcoke—a solid residue derived from the refinement of crude oil—has been growing due to its low cost. The use of petcoke is causing environmental concern associated with its high level of contaminants and air pollutant emissions, mainly particulate matter (PM). Given the impact of petcoke on the environment and human health, increased attention has been given to its production, storage, transportation, and application processes. The main goal of this work was to assess the effectiveness of placing a barrier to reduce PM emissions from petcoke in a harbor area. The Port of Aveiro, Portugal, was used as case study. Firstly, wind tunnel experiments were performed for different types of barrier to (i) assess the effect on PM emissions of different types of barriers, namely solid, porous, and raised porous barriers; (ii) determine the optimal size and location of the barrier to achieve maximum reduction of PM emissions; and (iii) estimate the impact of placing such barrier in the attenuation of petcoke emissions over the harbor area. Secondly, the numerical model VADIS (pollutant DISpersion in the atmosphere under VAriable wind conditions) was run to evaluate the effect of implementing the barrier on the local air quality. Results showed that the best solution would be the implementation of two solid barriers: a main barrier of 109 m length plus a second barrier of 30 m length. This measure produced the best results in terms of reduction of the dispersion of particulate matter from the petcoke stockpile and minimization of the PM concentrations in the harbor surrounding area.publishe

One-pot synthesis of CaAl-layered double hydroxide-methotrexate nanohybrid for anticancer application

One-pot (co-precipitation) synthesis route was employed for the first time to synthesize pristine CaAl-layered double hydroxide (LDH) and in-situ intercalation of the anticancer drug methotrexate (MTX) to prepare CaAl-LDH-MTX nanohybrid. An increase in the interplanar spacing of the (003) plane from 8.6 in pristine CaAl-LDH bilayered structure to 18.26 in CaAl-LDH-MTX nanohybrid indicated successful intercalation of anionic MTX into the interlayer space of CaAl-LDH. This was supported by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.7 in pristine LDH to 18.31 in LDH-MTX nanohybrid. Particle size and morphology analysis of pristine CaAl-LDH and LDH-MTX nanohybrid using both dynamic light scattering (DLS) technique and transmission electron microscopy (TEM) indicated a decrease in average particle size in LDH-MTX nanohybrid as compared with that of pristine LDH. Thermogravimetric analyses (TGA) revealed an enhancement in decomposition temperature of MTX bound to CaAl-LDH nanohybrid to as compared with in pure MTX molecule, indicating enhanced thermal stability, which supports stable electrostatic interaction of MTX within the interlayer position of LDH. CHN (carbon hydrogen nitrogen) analysis revealed nearly 49 wt% of MTX loading into CaAl-LDH, which closely matched with the result obtained from TGA of the nanohybrid. Cumulative release of MTX from CaAl-LDH-MTX in phosphate buffer solution showed a non-linear dependence with incubation time. Release mechanism of MTX from LDH-MTX nanohybrid was governed by diffusion mechanism at physiological pH of 7.4. The in vitro cytotoxicity study of LDH-MTX nanohybrid using MG-63 human osteosarcoma cell line indicated enhanced inhibition of the cancer cell proliferation compared with the MTX drug alone