a b s t r a c tWe herein report the modification of coconut shell-based biochar by ultraviolet (UV) irradiation to yield a highly efficient adsorbent for Pb(II) and Cu(II). Analysis of the physicochemical properties and structural characteristics of the modified biochar indicated that it contained a greater number of oxygen-containing functional groups on its surface compared with pristine biochar. In addition, the kinetics and adsorption isotherms for the adsorption of heavy metals by the biochar sample were investigated. More specifically, the pseudo-second order equation provided the best correlation for the adsorption process, and the adsorption isotherms fitted well with the Langmuir model. Furthermore, the Langmuir adsorption capacities of the modified biochar towards Pb(II) and Cu(II) were 66.86 and 7.78 mg g −1 , respectively, which represented 3.57-and 2.39-fold increases compared to the pristine biochar capacities. Moreover, batch sorption experiments demonstrated that the dosage and solution pH affected the removal of these metals from aqueous solutions by biochar. We also found that the adsorption mechanisms of Pb(II) and Cu(II) on modified biochar occurred mainly through surface sorption, likely involving the oxygen-containing functional groups present on the modified surface. Thus, we successfully demonstrated that UV irradiation is a promising modification approach for enhancing the adsorption ability of biochar.
Although numerous studies have been carried out to study haze formation in the North China Plain (NCP) and Northeastern Plain (NP), little is known about the chemical compositions and haze formations in Qinhuangdao city, which is located in the northeast edge of the NCP and adjacent to the NP. In this study, water‐soluble inorganic ions, organic carbon and elemental carbon (EC) were analysed offline during two haze periods from October 29 to November 7, 2021. The results showed that NO3− and organic matter (OM) accounted for 34.81% and 21.15% of total PM2.5 mass concentration, respectively, followed by NH4+ (14.06%) and SO42− (12.33%). The sulphur oxidation ratio and nitrogen oxidation ratio as well as OM/EC ratio on haze days were higher than those on non‐haze days, suggesting both high secondary inorganic and organic aerosol formation on haze days under high relative humidity. Source apportionment results showed that marine aerosols contributed small of total aerosol particle loads, while the combustion‐related sources were the most, possibly coal combustion, biomass burning and vehicle emissions. Air masses during haze periods mainly came from southwest and west directions in this case. Further calculated meteorological data of 2018–2021 showed high PM2.5 mass in Qinhuangdao were mainly affected by low‐speed southwest wind in autumn. The results highlighted the important role of long‐range transport of air pollutants from the NCP instead of the NP on haze formation in autumn in Qinhuangdao.
Soil contamination by heavy metals is of great concern at the global scale because of its serious potential hazards to agricultural productivity, water environment, and human health [1][2][3]. In China, approximately 20 million hectares of arable land, equivalent to nearly 20% of China's total agricultural land area, is subject to heavy metal contamination [2]. The major heavy metal contaminants are cadmium (Cd) followed by lead (Pb), copper (Cu), etc. These heavy metals often coexist in contaminated soils and cannot be naturally degraded [4,5]. Therefore, for safe food production it is imperative to develop effective methods of remediating soils co-contaminated with heavy metals. AbstractIn this study, biochar (BC), triple superphosphate (TSP), and TSP+BC amendments were utilized for remediation of Cd, Pb, and Cu co-contaminated agricultural soils. The toxicity characteristic leaching procedure (TCLP), the European Community Bureau of Reference (BCR), X-ray diffraction, and scanning electron microscopy-energy dispersive spectrometer techniques were employed to evaluate the effectiveness of the three types of amendments. After soil amendment, pH, heavy metal concentrations in TCLP extracts, and BCR speciation of heavy metals showed significant changes. The application of BC, TSP, and TSP+BC to co-contaminated soils slightly increased soil pH; decreased Pb, and Cu leachability in the TCLP extracts; and lowered the concentrations of the acid-soluble fraction of heavy metals. The application of TSP+BC mixture at the same dose as BC and TSP produced the greatest reduction in available heavy metal concentration. The optimum mass ratio of TSP to BC was 1:3. Overall, the TSP+BC mixture was highly effective in immobilizing Cd, Pb, and Cu in co-contaminated agricultural soils. The experimental results demonstrate that the rational application of the TSP and BC provides benefits of retrenching phosphorus resources, decreasing phosphorus pollution, and lowering the feed costs of debasing soil remediation treatments.
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