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Hollow polyethylene spheres were achieved from solution-based ɑ-diimine nickel catalyst system with morphological controllable one-step synthesis. • Homogenous ɑ- diimine nickel complexes often produce bulk viscous polyethylene. • Spherical hollow polyethylene produced by coordination dispersion polymerization. • Tri-nuclear nickel complex show high activity for ethylene polymerization. In this paper, ɑ-diimine nickel catalyst without immobilization was successfully used for one-step synthesis of spherical hollow polyethylene particles at mild condition (1.0 MPa, 25 °C) by conducting coordination dispersion polymerization. It was found 2-methyl-2-pentanol (MP) played a key role in the formation of the unusual hollow particular morphology. By varying the addition amount of MP, changing the bulky groups of alkyl aluminum, and adjusting the concentration of nickel catalyst, the particle size was finely tuned. A plausible mechanism was proposed to interpret the formation of these polyethylene hollow particles. [ABSTRACT FROM AUTHOR]

Abstract The groundwater is an important route of human exposure to kinds of contaminants. This study was carried out to investigate the occurrence and spatial distribution of groundwater arsenic in the Jinghui irrigation district in Shaanxi Province, China. The water contamination was assessed for drinking purposes by comparing it to national guidelines, and the impacts of arsenic on human health were quantified using the health risk assessment model recommended by the USEPA. The results show that the concentration of groundwater arsenic ranges from 0.0012 to 0.0190 mg/L (average 0.0054 mg/L), and 2.58% of groundwater exceed the national guidelines of 0.01 mg/L for drinking. The carcinogenic risk of arsenic affecting adults has reached 3.50 × 10−4, significantly exceeding the national guideline (1.00 × 10−4.) The health risks resulting from oral exposure are higher than those of dermal exposure. The carcinogenic risk for adults is higher than that for children, while the non-carcinogenic risk for children is higher than that for adults. The area ratio of the carcinogenic risk is 42.82%, and the area of the non-carcinogenic risk is 69.19%. Groundwater arsenic mainly originates from the discharge of industrial wastewater and the slowly release of natural sediments. The results of this study can help to set up suitable management strategies to guarantee water supply and health safety for local residents. Highlights • The concentration of groundwater arsenic exceeds the national guideline. • The carcinogenic risk for adults is higher than that for children. • Risks resulting from oral exposure are higher than those of dermal exposure. • The area of the non-carcinogenic risk is greater than that of carcinogenic risk. • Arsenic mainly originates from the industrial wastewater and the natural sediments. [ABSTRACT FROM AUTHOR]