Application of a hybrid GEM-CMB model for source apportionment of PAHs in soil of complex industrial zone.

Accurate source apportionment is essential for preventing the contamination of pervasive industrial zones. However, a limitation of traditional receptor models is their negligence of transmission loss, which consequently reduces their accuracy. Herein, chemical mass balance (CMB) and generic environmental model (GEM) was fused into a new method, which was employed to determine the traceability of polycyclic aromatic hydrocarbons (PAHs) in a complex zone containing three coking plants, two steel plants, and one energy plant. Five categories of fingerprints comprising various compounds were established for the six plant sources where seven PAHs with low-high rings were screened as the best. Considering volatilization, dry deposition, and advective and dispersive transport, the GEM model generated 232 "compartments" in multimedia to capture subtle variations of PAHs during transmission. More than 90 % of the transmission of the seven PAHs varied between 0.4 % and 6.0 %. Over pure CMB model, acceptable results and best-fit results improved by 1.6-44.4 % and 0.3-80.8 % in the GEM-CMB model. Additionally, the coking, steel, and energy industries accounted for 36.4-56.1 %, 25.6-41.7 %, and 18.3-23.6 % of PAHs sources at four receptor points, respectively. Furthermore, quantifying contaminant loss rendered the traceability results more realistic, judged by distances and discharge capacities. Accordingly, these outcomes can help in precisely determining soil contamination.

Reduction-Magnetic Separation of Pickling Sludge by Biomass Pyrolysis Reducing Gas.

The neutralization process of carbon steel pickling wastewater produces a large amount of steel hydrochloric acid pickling sludge (SHPS), and improper treatment of this sludge poses a serious threat to the environment. Considering that SHPS contains a large amount of iron oxide and given the huge demand for iron concentrate in China's ironmaking industry, refining iron oxide in SHPS into iron concentrate will have great environmental and economic benefits. This paper proposes a new method that uses biomass (corncob) to replace conventional coal-based reductants for the recovery of iron components in SHPS to simultaneously utilize two kinds of solid waste resources. Factors that affect the iron recovery rate and iron grade of SHPS, such as the reaction temperature, corncob dosage, residence time, and magnetic field strength, were studied using a fixed bed and a magnetic separator. These studies were combined with thermodynamic analysis, thermogravimetric analysis, X-ray diffraction, inductively coupled plasma-mass spectrometry, gas chromatography, etc. The results showed that when the reaction temperature was 680 °C, the corncob dosage was 5%, the residence time was 20 min, and the magnetic field strength was 200 mT, the recovery rate of iron reached 91.83%, and the iron grade of the recovered products was 67.72%, meeting the level I requirements in GB/T 32545-2016. Based on this result, a process involving SHPS reduction roasting with corncob pyrolysis reducing gas-magnetic separation was established to recover iron from SHPS. This process not only effectively utilizes the iron oxide in SHPS by converting it into iron concentrate powder for the ironmaking industry but also proves that the pyrolysis gas of corncob has good reduction ability.

Distribution, influence factors, and biotoxicity of environmentally persistent free radical in soil at a typical coking plant.

Environmentally persistent free radicals (EPFRs) are emerging pollutants in contaminated soils and have attracted significant attention. Chinese coke production making a great contribution to the globe is increasingly identified as the non-ignorable source of EPFRs. However, the distribution level, influence factors, and biotoxicity of EPFRs at coking sites remain poorly understood. Herein, a typical coking plant in Tangshan, China, featuring two functional regions (the reconstructed project (RP) and elimination engineering (EE)) was used to study the existence of EPFRs. The spin density of the EPFRs in coking soils was 3.20 × 1020-3.11 × 1021 spins/g with g-factor values of 2.0020-2.0036. The EPFRs presented higher concentrations and g-factor values in RP region than in EE region, and a mixture of carbon-centered radicals and carbon-centered radicals with adjacent oxygen atoms as well as carbon-centered radical was ascertained in the former and the latter, respectively. Correlation analysis and FT-ICR-MS results indicated that polycyclic aromatic hydrocarbons (PAH) together with other unsaturated hydrocarbons and condensed aromatic contaminants, might contribute to the EPFRs formation in the soils of RP region, whereas PAHs were the main source of EPFRs in EE region. Soil components were determined to investigate the influence factors in EPFRs formation. Cu and Fe2O3 were recognized as the markedly positive influence factors, while TOC had a negative impact on EPFR formation. Visible light irradiation can induce the transformation and generation of EPFRs. As representative contaminants, both toluene and 2-chlorophenol can create EPFRs in coking soil under visible light irradiation. The potential biotoxicity tests of Photobacterium phosphoreum T3 spp. showed that EPFRs from the soils diminished bacterial luminescence. Such effect was proven to be induced by the OH based on the quenching experiment. Understanding the influence factors of EPFRs formation and their biotoxicity in coking soils is critical for developing risk assessments and prevention strategies.

High-spatial-resolution VOCs emission from the petrochemical industries and its differential regional effect on soil in typical economic zones of China.

Volatile organic compounds (VOCs) are toxic to the ecological environment. The emission of VOCs into the atmosphere has already caused attention. However, few studies focus on their regional effects on soil. As a major VOCs source in China, research on the effect of petrochemical industry on the environment is urgent and essential for regional control and industrial layout. This study established national VOCs emission inventory of five petrochemical sub-industries and spatial distribution based on consumption of raw material or products' yield and 28,888 factories. The VOCs emissions showed continuously increasing trend from 2008 to 2019, with cumulative 1.83 × 107 t, wherein these from rapid economic development zones accounted for 66.10%. The detected concentrations of VOCs in various industries combined with meteorological parameters were used in Resistance Model to quantify regional dry deposition. Higher concentrations of 111 VOC species were 238.27, 260.01, 207.54 µg·m-3 from large-scale enterprises for crude oil and natural gas extraction, oil processing, synthetic rubber and resin, leading to higher deposition ratios of 0.81%-0.94%, 0.70%-0.81%, 1.50%-1.75% in rapid economic development zones, respectively. The regional climate condition played a dominant role. Annual VOCs dry deposition amount in rapid economic development zones was calculated to be totally 6.38 × 103 t using obtained deposition ratios and emissions, with 3.21 × 103 t in Bohai Economic Rim (BER), 2.42 × 103 t in Yangtze River Economic Belt (YREB), 748.43 t in Pearl River Delta (PRD). Generally, crude oil and natural gas extraction, oil processing, synthetic rubber and resin contributed 13.09%, 57.77% and 29.14%, respectively. The proportion of synthetic rubber and resin for dry deposition increased by 5.04%-18.81% compared with VOCs emissions in BER and YREB. In contrast, it declined from 45.52% for emission to 29.86% for deposition due to absolute dominance of small-scale enterprises in PRD. Overall, VOCs control from oil processing was significant, especially in BER.

[VOCs Emission Inventory and Variation Characteristics of Artificial Sources in Hubei Province in the Yangtze River Economic Belt].

In this study, a 2018 anthropogenic volatile organic compounds (VOCs) emission inventory in Hubei Province was conducted using the emission factor method based on activity levels of five sources. The emission characteristics and variation trends of process sources from 2009 to 2018 were further analyzed. Total anthropogenic VOCs emissions were 6.52×105 tons in Hubei Province, accounting for about 6.41% of the country's total omissions. The contributions of fossil combustion sources, process sources, solvent sources, mobile sources, and waste disposal sources were 3.26%, 76.39%, 4.54%, 14.72%, and 1.09%, respectively. Process sources involving 45 sub-categories of nine industries accounted for a significant proportion of VOCs emissions, with Wuhan and Yichang recording the highest VOCs emission levels. The VOCs emissions intensity of each city and state were analyzed based the level of economic activity and territorial area. Tianmen and Shennongjia had higher VOCs emissions per unit of GDP, while Wuhan, Ezhou, and Tianmen had higher VOCs emissions per unit area. Regarding process source contributions, VOCs emissions increased progressively to 2.45×105 tons in 2009 and then stabilized between 2015 and 2017 with maximum emissions of 7.01×105 tons. In 2018, VOCs emissions decreased to 4.98×105 tons. This trend was similar to national anthropogenic emissions. Two industrial sectors, namely chemical raw materials and rubber and plastics, were the main driving force with contributions of 33.85%-51.55% and 7.07%-38.13%, respectively. Among them, the production of chemicals and active pesticide and pharmaceutical ingredients played an important role in contributing to VOCs emissions, while emissions during foam plastics production varied greatly, increasing sharply to more than 2.00×104 tons in 2015-2017. Under the guidance of the relevant national and local policies, emissions from key industries were significantly reduced in Hubei Province.

Recent advances in the removal of persistent organic pollutants (POPs) using multifunctional materials:a review.

Persistent organic pollutants (POPs) have gained heightened attentions in recent years owing to their persistent property and hazard influence on wild life and human beings. Removal of POPs using varieties of multifunctional materials have shown a promising prospect compared with conventional treatments. Herein, three main categories, including thermal degradation, electrochemical remediation, as well as photocatalytic degradation with the use of diverse catalytic materials, especially the recently developed prominent ones were comprehensively reviewed. Kinetic analysis and underlying mechanism for various POPs degradation processes were addressed in detail. The review also systematically documented how catalytic performance was dramatically affected by the nature of the material itself, the structure of target pollutants, reaction conditions and treatment techniques. Moreover, the future challenges and prospects of POPs degradation by means of multiple multifunctional materials were outlined accordingly. Knowing this is of immense significance to enhance our understanding of POPs remediation procedures and promote the development of novel multifunctional materials.

Photochemical reactions of 1,3-butadiene with nitrogen oxide in different matrices: Kinetic behavior, humidity effect, product and mechanisms.

Understanding the photochemical reaction process between VOCs and co-pollutants in the troposphere is crucial for controlling the haze. The photochemical reactions of 1,3-butadiene (1,3-BD) with NO were carried out at 308 K for up to 96 h in clean air with various relative humidity (RH) values, and actual haze atmosphere. In the haze, the representative pseudo-first-order kinetic rate constants of the 1,3-BD-NO system was 1.53 time higher than those in dry clean air. The effect of the RH (0%-80%) on the conversion behavior of the 1,3-BD-NO system in clean air was studied, revealing that increasing RH promoted the photochemical reaction in the low range of 0%-40% but retarded it in the high range of 40%-80%. Interestingly, OH radicals were directly detected under different RH values, and the strongest OH signal was obtained at an RH of 40%. Multiple macromolecular products with carbon numbers of 10-36 were identified. Unexpectedly, richer products and extended unsaturation range were detected at an RH of 40% than 0%. The photochemical products were also analyzed using ion chromatography. A reaction mechanism was proposed from the detected NO2, O3, OH, HNO2, HNO3, organic acids and macromolecular products.