Surface dusts from electronic and electrical material maintenance workshops may present significant environmental contamination. The aim of this study was to determine levels of selected heavy metals (Cu, Ni, Co, Cd, Cr, Pb, Zn, and Fe) in surface dust samples collected from electronic and electrical device maintenance workshops located in Ambo, Gedo, and Nekemte towns in Ethiopia. An optimized wet digestion procedure (acid mixture, 3 mL HNO₃, 2 mL HClO₄, and H₂O₂; digestion time, 2 h; digestion temperature, 200 °C) was employed prior to the metals determination by flame atomic absorption spectroscopy. The average amounts of the metals were found to be in the ranges of 73,970–58,980, 59,290–51,120, 8570–5778, 1273–1126, 708.9–261.6, 111.7–101.0, 114.9–89.50, and 12.30–9.620 mg/kg for Pb, Fe, Cu, Cr, Zn, Co, Ni, and Cd, respectively. The results showed that the investigated surface dust samples contained significant levels of the analyzed heavy metals compared to soil samples collected from the corresponding control sites. The heavy metal concentrations in the investigated samples from the three towns followed a decreasing order Pb > Fe >> Cu >> Cr > Zn > Co > Ni > Cd, indicating the presence of elevated amount of Pb in the surface dust samples. The significantly high levels of heavy metals detected in all surface dust samples from electronic and electrical device maintenance shops could be inferred to the seepage of these metals from electronic materials during the maintenance procedures. Based on the result obtained, we strongly recommend a strict monitoring and disposal (policy issue) of wastes generated from electronic and electrical device maintenance shops.

Biochar is being examined as a potential sorbent for organic pollutants in the environment including phthalate esters (PAEs). It has been noted that nano-scale biochar particles displayed stronger migration potential than other particles, which poses the potential risk of pollutant transfer through the environment. In this present study, we examined the influence of sub-millimeter (200–600 μm), micron-scale (10–60 μm), and nano-scale (0.1–0.6 μm) biochar on diethyl phthalate (DEP, as a model) adsorption using particles derived from corn straw and rice husk biochar. Meanwhile, the interaction between adsorption capacity and initial pH was also considered. Our results showed that the adsorption capacity of biochar for DEP increased with decreasing particle size, and was considerably higher for nano-scale biochar than for other particles. This was attributable to its developed pore structure and higher specific surface area (SSA), especially the dominant micropore (292.73 m²/g), suggesting that the adsorption of DEP to nano-scale biochar was dominated by pore-filling rather than π-π EDA and H bonding that was applied to biochar of larger, more typical dimensions. The adsorption capacity of nano-scale biochar for DEP was markedly decreased when initial pH was decreased from 9.0 to 3.0. Because an acid environment could reduce the absolute surface charge on nano-scale biochar, it was easier for the particles to agglomerate. Nano-scale biochar therefore have higher activity in alkaline conditions, which could pose certain risks through their application into the environment.

In previous studies, inhalation cancer risk was estimated using conventional risk assessment method, which was normally based on compound-specific analysis, and cannot provide substantial data for source-specific particulate matter concentrations and pollution control. In the present study, we applied an integrated risk analysis method, which was a synthetic combination of source apportionment receptor model and risk assessment method, to estimate cancer risks associated to individual PAHs coming from specific sources. Personal exposure particulate matter samples referring to an elderly panel were collected in a community of Tianjin, Northern China, in 2009, and 12 PAH compounds were measured using GC-MS. Positive matrix factorization (PMF) was used to extract the potential sources and quantify the source contributions to the PAH mixture. Then, the lung cancer risk of each modeled source was estimated by summing up the cancer risks of all measured PAH species according to the extracted source profile. The final results indicated that the overall cancer risk was 1.12 × 10⁻⁵, with the largest contribution from gasoline vehicle emission (44.1%). Unlike other risk estimation studies, this study was successful in combining risk analysis and source apportionment approaches, which allow estimating the potential risk of all source types and provided suitable information to select prior control strategies and mitigate the main air pollution sources that contributing to health risks.

The ability of standard soils to capture heavy metals or polycyclic aromatic hydrocarbons (PAHs) from ammoniacal copper zinc arsenate (ACZA)– or creosote-treated wood, respectively, was assessed using pressure-treated posts immersed in a freshwater pond. The soil, in heat-sealed, permeable plastic mesh sachets, was able to intercept copper, zinc, arsenic, and PAHs migrating from the posts. Chemical levels were much higher immediately adjacent to the posts and declined with distance from the posts. Metals were consistently detected around ACZA-treated posts, while 10 of the 16 EPA priority pollutants were detected in at least one sachet embedded around creosote-treated posts at each sampling point. These results were consistent with traditional sediment sampling methods. The primary advantages of the sachets were their consistency in terms of soil characteristics and the ease with which they could be retrieved from the pond. Further studies are planned to better understand the role of soil characteristics in the sachets on the ability to capture migrating preservatives.

Air pollution has caused huge losses of life and property. So, how to choose a practically effective scheme to m.itigate air pollution is of great significance. However, such a selection problem of treatment schemes represents really a group negotiation process of many decision makers (DMs), involving a variety of fuzzy information and preferences. To successfully address this selection problem, this paper proposes a novel group negotiation decision model by jointly employing various approaches, such as hesitant fuzzy set, grey target, grey incidence analysis, and graph model for conflict resolution (GMCR). Then, this model is used to determine the equilibrium schemes for treating air pollution. It is expected that this work provides a method for Chinese government to introduce programs to target air pollution control.

Leather tanneries which produce significant amounts of solid waste, effluents, and emissions are a major contributor to industrial waste. A cleaner production program was launched by the government of Pakistan to implement the cleaner production measures for tanneries of Sialkot from 1999 to 2005. The main objective of this study is to identify the impact of a cleaner production program, along with other determinants of a cleaner production in the leather industry. The study analyses firm-level primary data collected from leather tanneries in Sialkot. The primary data were collected from tanneries in Sialkot. The econometric analysis is conducted using the Poisson regression analysis. Overall results show that there is no significant impact of cleaner production in 2015, while the panel data results indicate that the effect of cleaner production support by CPC on cleaner production practices diminished once the support came to an end. The other main factor is firm size, which indicates the financial position of the firm; international and regulator pressures are major determinants of the adoption of cleaner production measures. The analysis also indicates that there is higher probability of large firms adopting a cleaner production in comparison with small ones. Export orientation of firms is another important determinant of cleaner production. The enforcement of the environment compliance laws also has positive effect. The compliance with cleaner production measures is quite low, at 6.4 out of 19 cleaner production practice measures. There is a need to adopt measures that are environmentally friendly and are favorable towards both labor health and product quality, which are important for the sustainable growth of the tanning industry.

Removal of the heavy metal ions in aqueous solution is an important technology for waste water treatment. The effects of using ultrasonic and microwave on synthesizing Pb²⁺, Zn²⁺, and Cu²⁺ imprinted mesoporous adsorbents (Pb-IMA-UM, Zn-IMA-UM, and Cu-IMA-UM) and their dynamic adsorption properties were studied. The microstructure and composition of the ion-imprinted mesoporous adsorbents were discussed in detail by TEM, FTIR, N₂ adsorption-desorption, XRD, and EDS. The pore sizes of mesoporous absorbents were improved more uniformly by using ultrasonic agitation than magnetic stirring. The elution efficiency of imprinting ions can be enhanced by microwave elution. Prepared Pb-IMA-UM, Zn-IMA-UM, and Cu-IMA-UM were used for dynamic adsorption study of heavy metals. The detected optimal feed rate was 20.0 mL/min and the influent concentration was 60 mg/L; the equilibrium adsorption capacities of Pb-IMA-UM, Cu-IMA-UM, and Zn-IMA-UM could reach 198 mg/g, 51.5 mg/g, and 57.3 mg/g, respectively. The dynamic regeneration performance of the adsorbent was also investigated with the Cu-IMA-UM sample. The adsorption rate remained above 89% after five dynamic regeneration experiments. At last, the actual wastewater from an electroplating industry was used as the research object. Three groups of dynamic adsorption coefficient contours of Pb-IMA-UM, Zn-IMA-UM, and Cu-IMA-UM were obtained when influents flowed into three adsorption columns separately. The experimental results showed that an ion-imprinted adsorbent had a much better adsorption capacity of imprinted ions under the various metals mixed conditions.

Ball-milled biochars (BM-biochars) were produced through ball milling of pristine biochars derived from different biomass at three pyrolysis temperatures (300, 450, and 600 °C). The results of scanning electron microscopic (SEM), surface area, hydrodynamic diameter test, and Fourier transform infrared spectroscopy (FTIR) revealed that BM-biochars had smaller particle size (140–250 nm compared to 0.5–1 mm for unmilled biochar), greater stability, and more oxygen-containing functional groups (2.2–4.4 mmol/g compared to 0.8–2.9 for unmilled biochar) than the pristine biochars. With these changes, all the BM-biochar-modified glassy carbon electrodes (BM-biochar/GCEs) exhibited prominent electrochemical properties (e.g., ΔEₚ of 119–254 mV compared to 850 mV for bare GCE). Cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) show that ball-milled 600 °C biochar/GCE (BMBB600/GCE and BMBG600/GCE) had the smallest peak-to-peak separation (ΔEₚ = 119 and 132 mV, respectively), series resistance (RS = 88.7 and 89.5 Ω, respectively), and charge transfer resistance (RCT = 1224 and 1382 Ω, respectively), implying its best electrocatalytic activity for the reduction of Fe(CN)₆³⁻. It is supposed that the special structure (i.e., internal surface area, pore volume, oxygen-containing functional groups, and graphitic structure) facilitates the electron transfer and reduces interface resistance. Economic cost of BM-biochar/GCE was 1.97 × 10⁻⁷ USD/cm², much lower than that of a “low-cost platinum electrode” (0.03 USD/cm²). The results indicate potential application of the novel BM-biochar for low cost and high efficient electrodes. Graphical abstract

For heavy duty applications like power generation and transportation, the best option is the compression ignition engines, but the major concerns are the rising prices and environmental issues due to the rapid depleting sources of conventional fossil fuels. The present investigation is to study the performance and emission characteristics of a single cylinder four-stroke, air-cooled direct injection diesel engine runs with an alternate fuel as waste high density polyethylene plastic oil (HDPE) obtained by catalytic pyrolysis. At constant speed, test fuels have been experimented successfully to determine the engine performance such as brake thermal efficiency, brake specific energy consumption, and exhaust gas emissions such as carbon monoxide, carbon dioxide, oxides of nitrogen, and unburned hydrocarbons. The result shows that the brake thermal efficiency is lower at all load conditions when compared to diesel fuel whereas the brake specific energy consumption decreases with increase in engine load and increases with increase in waste plastic oil blend ratio. CO emission increases and NOₓ emission level decreases with enhancement in engine load whereas the NOₓ emission and CO emission augments with increase in waste plastic oil blend percentage. But in case of NOₓ emission increase in concentration of waste plastic oil with diesel leads to raise in emission level. By using thermal imager, the link between in-cylinder temperature and NOₓ emission has been fixed. With the help of this course of action, it has been observed that in-cylinder temperature plays the major role in NOₓ concentration.

The environmental and human health risk posed by veterinary antibiotics is of global concern. Antibiotic uptake by herbal plants has been studied, but little is known about perennial woody fruit crops. Litchi (Litchi chinensis Sonn.), a longevial fruit tree, is routinely fertilized with animal manure and, therefore, may be at risk of antibiotic uptake into its fruits. This study investigated the degradation of chlortetracycline and doxycycline present in manure used to amend orchard soil, and their subsequent assimilation by litchi plant, as affected by manure application rate. The results show that half-lives of chlortetracycline and doxycycline in soil were decreased by increased manure rate, with an average of 27 and 59 days, respectively. Chlortetracycline was readily transported to litchi shoots and increased with the growth of litchi plants. Doxycycline predominantly remained in the roots, and underwent growth dilution in the plants. The two tetracyclines could not be detected in fruits from litchi trees when applied with manures, at various rates, over 2 years. For litchi, chlortetracycline may pose human health risk through manure application, but doxycycline is unlikely to do so. Long-term field experiments are required to monitor antibiotic accumulation in fruits of perennial fruit trees fertilized with animal manure.