Search

[Display omitted] • Efficient evaporation and pollution resistance are achieved simultaneously. • The hydrophilic modification by adding polyethylene glycol is economical. • The doping Enteromorpha reduces the cost and improves the mechanical property. • PEGA forms unstable hydrogen bonds with water to promote evaporation and detachment. • The evaporator can float on the surface of oily seawater to obtain fresh water. Photothermal evaporation using solar energy is a sustainable way to produce fresh water from seawater. Aiming to explore functional materials as a solar-energized evaporator with enhanced evaporation rate and pollutant tolerance, this study was to synthesize a self-floating composite graphene aerogel (GA) doped with Enteromorpha and modified polyethylene glycol (PEG), named as PEGA using solar energy for desalination. Physio-chemical properties and evaporative mechanism of PEGA were experimentally investigated and analyzed with respect to molecular weight, PEG dosage, and ratio of Enteromorpha and graphene oxide. Experimental data revealed that the modification of PEG improved hydrophilic functional ability of PEGA, resulting in increasing the evaporation rate and photothermal conversion efficiency up to 2.55 kg/(m2·h) and 105.71 %, respectively. The ion removal rate of seawater exceeds 99.99 % via the PEGA conducted solar evaporation. Furthermore, PEGA possessed an excellent property of salinity emulsion pollution tolerance. Particularly, the evaporation rate of the PEG-modified biomass-based aerogel was 2.84 kg/(m2·h) in a 15 wt% NaCl solution (1 sun, 6 h) and 2.50 kg/(m2·h) at 1 h. The formation of hydrogen bonds between –OH of PEG and water molecules assist to conduct water along the graphene matrix to improve water evaporation. The cost of the graphene aerogel modified by Enteromorpha was reduced by 38.88 % less than the original graphene aerogel. The results from this study will greatly promote the application of graphene aerogel for desalination via solar evaporation. [ABSTRACT FROM AUTHOR]

Although the mining area has been restored, the environmental problems caused by years of large-scale oil shale mining are still continuing, coupled with the intensive distribution of the surrounding petrochemical industry, posing a serious threat to the local ecological environment. In this study, we investigated eight heavy metals (Cu, Ni, Pb, Cd, As, Cr, Mn and Zn) contamination and distribution around mining area, evaluated the potential risks of environment, identified the main sources of metal pollution and performed source apportionment. The results showed that the original north and south dumps were seriously polluted, and the CF values were significantly higher than other sampling sites. Ni, Zn and Mn have high coefficients of variation, which may be greatly affected by human factors and especially the waste slag piled up. The concentration of heavy metals in the water was lower than in the soil; soil particles, pH, Eh and acid mine drainage influence the variation of heavy metal concentrations. As and Cd have very high RAC values, and accordingly they were mainly present in the exchangeable and reduced fractions. Mn was exposed to higher ecological risks, followed by Pb, although there were high loads on carbonate bound and oxidizable fractions. APCS-MLL receptor model was used to identify and apportionment three main sources of contamination. The mean contribution rates of industrial activity, atmospheric deposition and mixed sources accounted for 39.77%, 22.24% and 37.99%, respectively. Cluster analysis further classified the metal pollution sources according to the spatial distance of sampling points. • The former north and south dumps were heavily polluted after ecological restoration. • The physical and chemical characteristics of soil and AMD affect the concentration of heavy metals in soil and water. • The fraction distribution of heavy metals in soil determines the different ecological effects. • APCS-MLR receptor model was used to identify and analyze the sources of heavy. metal pollution. [ABSTRACT FROM AUTHOR]

Long-term heavy metals accumulation caused by acid mine drainage (AMD) irrigation in paddy soils poses a severe threat to environmental health. However, the soil adsorption mechanisms under AMD flooding remain unclear. This study provides key insights into the fate of heavy metals in soil, particularly the retention and mobility mechanisms of Cu (copper) and Cd (cadmium) after AMD flooding. The migration and fate of Cu and Cd in uncontaminated paddy soils treated by AMD in Dabaoshan Mining area was investigated via column leaching experiments in the laboratory. The maximum adsorption capacities of Cu (658.04 mg kg−1) and Cd (335.20 mg kg−1) cations were predicted and the breakthrough curves were fitted using the Thomas and Yoon-Nelson models. Our findings demonstrated that Cd was more mobile than Cu. Furthermore, the soil had a greater adsorption capacity for Cu than Cd. Tessier's five-step extraction method was used to determine Cu and Cd fractions in leached soils at different depths and times. After AMD leaching, the relative and absolute concentrations of the easily mobile forms were all increased at different soil depths, thus increasing the potential risk to the groundwater system. Mineralogical characterization of the soil indicated that AMD flooding leads to the formation of mackinawite. This study provides insights into the distribution and transportation processes of soil Cu and Cd and their ecological effects under AMD flooding, as well as a theoretical basis for the establishment of corresponding geochemical evolution models and environmental governance in mining areas. • Long-term acid mine drainage (AMD) promotes secondary iron mineral formation. • Cu was preferentially adsorbed and retained in paddy soils compared to Cd. • The exchangeable and carbonate-bound Cd remarkably increased during AMD flooding. • Cu was mainly in Fe/Mn oxides-bound and organic matter-bound under AMD. [ABSTRACT FROM AUTHOR]