Mechanisms of Cr(VI) reduction by Fe(II) modified zeolite (clinoptilolite/mordenite) and vermiculite were evaluated. Adsorbents were treated with Fe(SO₄)·7H₂O to saturate their exchange sites with Fe(II). However, this treatment decreased their CEC and pHPZC, probably due to the dealumination process. Vermiculite (V-Fe) adsorbed more Fe(II) (21.8 mg g⁻¹) than zeolite (Z-Fe) (15.1 mg g⁻¹). Z-Fe and V-Fe were used to remove Cr(VI) from solution in a batch test to evaluate the effect of contact time and the initial concentration of Cr(VI). The Cr(VI) was 100% reduced to Cr(III) by Z-Fe and V-Fe in solution at 18 mg L⁻¹ Cr(VI) after 1 min. Considering that 3 mol of Fe(II) are required to reduce 1 mol of Cr(VI) (3Fe⁺² + Cr⁺⁶ → 3Fe⁺³ + Cr⁺³), the iron content released from Z-Fe and V-Fe was sufficient to reduce 100% of the Cr(VI) in solutions up to 46.8 mg L⁻¹ Cr(VI) and about 90% (V-Fe) and 95% (Z-Fe) at 95.3 mg L⁻¹ Cr(VI). The Fe(II), Cr(III), Cr(VI), and K⁺ contents of the adsorbents and solutions after the batch tests indicated that the K⁺ ions from the [Formula: see text] solution were the main cation adsorbed by Z-Fe, while vermiculite did not absorb any of these cations. The H⁺ of the acidic solution (pH around 5) may have been adsorbed by V-Fe. The release of Fe(II) from Z-Fe and V-Fe involved cation exchange between K⁺ and H⁺ ions from solution, respectively. The reduction of Cr(VI) by Fe(II) resulted in the precipitation of Cr(III) and Fe(III) and a decrease in the pH of the solution to < 5. As acidity limits the precipitation of Cr(III) ions, they remained in solution and were not adsorbed by either adsorbent (since they prefer to adsorb K⁺ and H⁺). To avoid oxidation, Cr(III) can be removed by precipitation or the adsorption by untreated minerals.

Effluent organic matter (EfOM) contains a large number of substances that are harmful to both the environment and human health. To avoid the negative effects of organic matter in EfOM, advanced treatment of organic matter is an urgent task. Four typical oxidants (H₂O₂, PS, PMS, NaClO) and UV-combined treatments were used to treat micro-contaminants in the presence or absence of EfOM, because the active radical species produced in these UV-AOPs are highly reactive with organic contaminants. However, the removal efficiency of trace contaminants was greatly affected by the presence of EfOM. The degradation kinetics of two representative micro-contaminants (benzoic acid (BA) and para chlorobenzoic acid (pCBA)) was significantly reduced in the presence of EfOM, compared to the degradation kinetics in its absence. Using the method of competitive kinetics, with BA, pCBA, and 1,4-dimethoxybenzene (DMOB) as probes, the radicals (HO·, SO₄⁻·, ClO·) proved to be the key to reaction species in advanced oxidation processes. UV irradiation on EfOM was not primarily responsible for the degradation of micro-contaminants. The second-order rate constants of the EfOM with radicals were determined to be (5.027 ± 0.643) × 10² (SO₄⁻·), (3.192 ± 0.153) × 10⁴ (HO·), and 1.35 × 10⁶ (ClO·) (mg C/L)⁻¹ s⁻¹. In addition, this study evaluated the production of three radicals based on the concept of Rcₜ, which can better analyze its reaction mechanism.

In this study, a hydrotalcite (HT MgAl) was synthesized by coprecipitation at a constant pH. Its mixed oxide (HTC MgAl) was obtained for the removal of triclosan (TCS). The two materials were characterized by Scanning Electron Microscopy (SEM), X-ray Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). Measurements of N₂ physisorption and Point of Zero Charge (pHPZC) were also analyzed. TCS removal was investigated in terms of pH, adsorption kinetics, adsorption isotherms, and temperature. The HT MgAl material presented the typical morphology and crystalline structure of a hydrotalcite composed of C, O, Al, and Mg. This material is classified as a mesoporous material with a specific surface area of 114.92 m²/g and a pHPZC of 8.82. On the other hand, HTC MgAl material is a MgAl oxide with a surface area of 140 m²/g and a pHPZC of 11.06. Adsorption results showed that the highest adsorption capacity was obtained at pH 9.0 and at an equilibrium time of 24 h in both materials. The experimental kinetic and isotherm data were well-adjusted to the pseudo-first order and Freundlich models, respectively. This indicates a physisorption mechanism on heterogeneous materials. Therefore, the adsorption of TCS into the HT MgAl material was by way of ion exchange. On the other hand, the adsorption of TCS into the HTC MgAl material was by way of ion exchange and TCS intercalation by the reconstruction of the material. The TCS adsorption process was exothermic, and not spontaneous; hence, randomness was reduced.

Chemical signature of airborne particulates and deposition dusts is subject of study since decades. Usually, three complementary composition markers are investigated, namely, (i) specific organic compounds; (ii) concentration ratios between congeners, and (iii) percent distributions of homologs. Due to its intrinsic limits (e.g., variability depending on decomposition and gas/particle equilibrium), the identification of pollution sources based on molecular signatures results overall restricted to qualitative purposes. Nevertheless, chemical fingerprints allow drawing preliminary information, suitable for successfully approaching multivariate analysis and valuing the relative importance of sources. Here, the state-of-the-art is presented about the molecular fingerprints of non-polar aliphatic, polyaromatic (PAHs, nitro-PAHs), and polar (fatty acids, organic halides, polysaccharides) compounds in emissions. Special concern was addressed to alkenes and alkanes with carbon numbers ranging from 12 to 23 and ≥ 24, which displayed distinct relative abundances in petrol-derived spills and exhausts, emissions from microorganisms, high vegetation, and sediments. Long-chain alkanes associated with tobacco smoke were characterized by a peculiar iso/anteiso/normal homolog fingerprint and by n-hentriacontane percentages higher than elsewhere. Several concentration ratios of PAHs were identified as diagnostic of the type of emission, and the sources of uncertainty were elucidated. Despite extensive investigations conducted so far, the origin of uncommon molecular fingerprints, e.g., alkane/alkene relationships in deposition dusts and airborne particles, remains quite unclear. Polar organics resulted scarcely investigated for pollution apportioning purposes, though they looked as indicative of the nature of sources. Finally, the role of humans and living organisms as actual emitters of chemicals seems to need concern in the future.

Mining of minerals exerts adverse pressure on different compartments of environment directly or indirectly. Air is the worst affected environmental matrix, and it can carry the harmful effect of pollutants generated from mining activity even to distant places. The present study was undertaken to estimate the emission of particulate matter (PM₂.₅ and PM₁₀) from different activities undertaken in stone quarrying in Mahendragarh, Haryana. The results obtained from the present study indicated that drilling, blasting, crushing, and transport of mined material are chiefly responsible for the generation of dust. Whereas drilling, blasting, and loading were responsible for emission of higher fraction of PM₁₀, crushing and re-suspension of roadside dust from movement of vehicles resulted in generation of relatively higher fraction of finer dust (PM₂.₅). Modelling the transport of dust over the Hybrid Single-Particle Lagrangian Integrated Trajectory model revealed that the emitted particle may move up to the distance of about 40 km within 4 h of emission under average meteorological conditions. Fourier transform infrared (FTIR) spectroscopy analysis of dust confirmed the presence of calcite and gypsum, thus confirming the source as mining. The study concluded that generation of PM₂.₅-sized particles may impose serious respiratory health effects over the workers engaged in mining, crushing, and transportation of sandstone. Apart from it, population residing downwind of the mining area is particularly vulnerable to the pulmonary effects due to inhalation of dust.

The present study determined the most effective surfactants to remediate gasoline and diesel-contaminated soil integrating information from soil texture and soil organic matter. Different ranges for aliphatic and aromatic hydrocarbons (> C6–C8, > C8–C10, > C10–C12, > C12–C16, > C16–C21, and > C21–C35) in gasoline and diesel fuel were analyzed. This type of analysis has been investigated infrequently. Three types of soils (silty clay, silt loam, and loamy sand) and four surfactants (non-ionic: Brij 35 and Tween 80; anionic: SDBS and SDS) were used. The results indicated that the largest hydrocarbon desorption was 56% for silty clay soil (SDS), 59% for silt loam soil (SDBS), and 69% for loamy sand soil (SDS). Soils with large amounts of small particles showed the worst desorption efficiencies. Anionic surfactants removed more hydrocarbons than non-ionic surfactants. It was notable that preferential desorption on different hydrocarbon ranges was observed since aliphatic hydrocarbons and large ranges were the most recalcitrant compounds of gasoline and diesel fuel components. Unlike soil texture, natural organic matter concentration caused minor changes in the hydrocarbon removal rates. Based on these results, this study might be useful as a tool to select the most cost-effective surfactant knowing the soil texture and the size and chemical structure of the hydrocarbons present in a contaminated site.

In this study, the toxic effects of paraquat, one of the most commercially sold herbicides in the world, and the protective role of green tea leaf extract (GTLE) against these effects were investigated. Allium cepa L. bulbs (n = 16) were used as test material. One hundred milligrams per liter dose of paraquat and 190 and 380 mg/L doses of GTLE were preferred. Paraquat toxicity was investigated with the help of physiological (percent germination, root length, and weight gain), cytogenetic (mitotic index = MI, micronucleus = MN, and chromosomal damages = CAs), biochemical (superoxide dismutase = SOD, catalase = CAT, malondialdehyde = MDA), and anatomical (meristematic cell damages) parameters. A. cepa bulbs were divided into 6 groups as 1 control and 5 applications. The control group was germinated with tap water, and the application groups were germinated with paraquat and two different doses of GTLE. Germination was carried out at room temperature for 72 h. At the end of the period, A. cepa bulbs were prepared for physiological, cytogenetic, biochemical, and anatomical analyzes using routine preparation techniques. As a result, paraquat application caused a decrease in physiological parameters and an increase in cytogenetic (except MI) and biochemical parameters. Compared to the control (group I), the germination percentage decreased by 38%, root length 12.5 times, and weight gain 5 times decreased in group IV treated with paraquat. MDA level increased 2.58 times, SOD activity 2.48 times, and CAT activity 4.51 times increased. Paraquat application caused a decrease in the percentage of MI and an increase in the number of MN and CAs. Paraquat application caused CAs in the form of fragment, sticky chromosome, unequal distribution of chromatin, bridge, nucleus with vacuoles, nucleus bud, and reverse polarization. In the meristematic cells of the root tips applied paraquat, unclearly vascular tissue, flattened cell nucleus, epidermis, and cortex cell deformation were observed. The application of GTLE together with paraquat caused an increase in the physiological parameter values and a decrease in the cytogenetic (except MI) and biochemical parameter values. An improvement in the severity of damages induced by paraquat was also observed in root tip meristematic cells. It was determined that the improvements observed in all these parameters were related to the dose of GTLE applied. The 380 mg/L dose of GTLE provided more protection than the 190 mg/L dose. Compared to group IV in which paraquat was applied, the germination percentage increased by 21%, root length 5.83 times, and weight gain 2.92 times increased in group VI administered 380 mg/L dose of GTLE. In addition, MDA level decreased 1.78 times, SOD activity 1.59 times and CAT activity 1.65 times. In conclusion, paraquat administration at a dose of 100 mg/L caused physiological, cytogenetic, biochemical, and anatomical toxicity in A. cepa bulbs. GTLE application, on the other hand, resulted in improvements in the severity of this toxicity induced by paraquat, depending on the dose. Therefore, GTLE can be used as an effective nutritional supplement to reduce or prevent the toxicity caused by environmental agents such as pesticides.

This study aims to promote the high-quality development of regional agriculture. This study proposes a data-driven method for regional agricultural analysis and evaluation. Based on the data collection and processing related to regional agricultural development, the location entropy index was used to analyze the industrial agglomeration level, and the shift-share model was constructed to evaluate the industrial structure and competitiveness. Based on the above analysis and evaluation, high-quality development policy suggestions for regional agriculture were provided. Taking the agricultural development of the Yangtze River Delta from 2010 to 2019 as an example, this study shows the implementation process of the method. From the perspective of high-quality agricultural development in the Anhui Province, this paper proposes policy suggestions on industrial structure adjustment and promoting competitiveness. This study provides theoretical and methodological support for the development of high-quality regional agriculture.

The total factor CO₂ emission performance (TFCEP) of transportation industry has received increasing research interests, while existing literature pays little attention to its regional inequality and driving factors. In order to uncover the regional inequality of TFCEP in China’s transportation industry, this paper used Theil index and combined with geographical detector model (GDM) to explore the driving factors and their interactions on TFCEP in Chinese transportation industry. The results revealed that the TFCEP of transportation industry showed a promising increase during 2003–2017 with an annual growth rate of 0.12%, and the improvement was contributed by the technical efficiency change. The TFCEP in the Eastern region performed better than that in the Northeast, Central, and Western region. Regional inequality of TFCEP did exist and exhibited an obvious downward trend. The within-region inequality had a greater impact on the inequalities than between region. Freight turnover was the main driving factor of TFCEP in the transportation industry, followed by the energy intensity and per-capita GDP. In the Eastern and Western regions, freight turnover had the greatest impact on TFCEP, while in the Central and Northeastern regions, urbanization rate and energy intensity were the dominant factors, respectively. The interactions between energy intensity and freight turnover were highly influential. This paper provides important insights for different regions to formulate targeted carbon emission reduction policies.

Polycyclic aromatic hydrocarbons in biochars threaten their environmental application. The aging process may affect the concentration of PAHs, potential toxicity, and the properties of biochar. In this study, the aged biochars were obtained by simulated physical aging method (freeze-thaw treatment) and chemical aging method (H₂O₂ chemical oxidation). The PAH contents in biochars were measured, and their potential toxicity was assessed. Meanwhile, the influence of aging process on the physicochemical properties of biochar was also investigated. This study shows that the change of PAH content of aged biochars depended on pyrolysis temperature, ambient temperature, and oxidant concentration. Furthermore, physical and chemical aging process influenced the distribution of different ring PAHs in biochars. High-ring-number PAHs (four, five, six-ring PAHs) appeared in some aged biochar. Aging at ±20 °C and 0.01 M H₂O₂ increased the toxic equivalent quantity of all biochars which may be attributed to the change of the physicochemical properties influencing the different PAH ring distribution in biochars. The contribution of PAHs with different rings to TEQ varied in pristine and aged biochars. Physical and chemical aging process significantly affected the properties of biochars, such as element content, ash content, surface area, pore volume, pH, functional groups, and surface morphology. Correlation analysis confirmed that surface area and pore volume are dominant factors determining the PAH content in the biochars. Therefore, the aging process indeed affected the PAH concentration and toxicity of PAHs in biochar. Assessing PAH behavior in biochar over long timescales should not be overlooked.