Control of ammonia and urea emissions from urea manufacturing facilities of Petrochemical Industries Company (PIC), Kuwait

Hybrid ZnO nanostructures modified graphite electrode as an efficient urea sensor for environmental pollution monitoring

Herein, we propose a facile electrochemical sensing platform for urea detection using pencil graphite electrode modified nanocomposites of CuO/ZnO and Fe₂O₃/ZnO. The detection of urea is essential to monitor for identifying its pollution in the water, at the soil surface and in diagnosing urea cycle disorder related diseases. Therefore, an effective, accurate, cost-effective method of diagnosis is urgently needed. Nanostructured metal oxides have the potential ability to detect molecules even at trace level and to explore this, the present work is formulated with Cu and Fe based ZnO nanocomposites for enhancing the sensing performance towards electrochemical sensing of urea. The sensing responses were confirmed from the increase in oxidation current with respect to the concentration of urea. The results show that Fe₂O₃/ZnO coated graphite electrode has a higher response against urea compared to ZnO and CuO/ZnO. The cyclic voltammetry studies also validate urea sensing of Fe-ZnO in the linear range of 0.8 μg/mL to 4 μg/mL, with the detection limit of 2.5 μg/mL. This suggests that the cost-effective pencil graphite electrode modified Fe₂O₃/ZnO can be utilized as a promising analytical tool for urea sensing.

Evaluation of Industrial Urea Energy Consumption (EC) Based on Life Cycle Assessment (LCA)

With the increasingly prominent environmental problems and the decline of fossil fuel reserves, the reduction of energy consumption (EC) has become a common goal in the world. Urea industry is a typical energy-intensive chemical industry. However, studies just focus on the breakthrough of specific production technology or only consider the EC in the production stage. This results in a lack of evaluations of the life cycle of energy consumption (LcEC). In order to provide a systematic, scientific, and practical theoretical basis for the industrial upgrading and the energy transformation, LcEC of urea production and the greenhouse gas (GHG) emissions generated in the process of EC are studied in this paper. The results show that the average LcEC is about 30.1 GJ/t urea. The EC of the materials preparation stage, synthesis stage, and waste-treatment stage (ECRMP, ECPP, ECWD) is about 0.388 GJ/t urea, 24.8 GJ/t urea, and 4.92 GJ/t urea, accounting for 1.3%, 82.4%, and 16.3% of LcEC, respectively. Thus, the synthesis stage is a dominant energy-consumer, in which 15.4 GJ/t urea of energy, accounting for 62.0% of ECpp, supports steam consumption. According to the energy distribution analysis, it can be concluded that coal presents the primary energy in the process of urea production, which supports 94.4% of LcEC. The proportion of coal consumption is significantly higher than that of the average of 59% in China. Besides, the GHG emissions in the synthesis stage are obviously larger than that in the other stage, with an average of 2.18 t eq.CO2/t urea, accounting for 81.3% of the life cycle of GHG (LcGHG) emissions. In detail, CO2 is the dominant factor accounting for 90.0% of LcGHG emissions, followed by CH4, while N2O is negligible. Coal is the primary source of CO2 emissions. The severe high proportion of coal consumption in the life cycle of urea production is responsible for this high CO2 content of GHG emissions. Therefore, for industrial urea upgrading and energy transformation, reducing coal consumption will still be an important task for energy structure transformation. At the same time, the reformation of synthesis technologies, especially for steam energy-consuming technology, will mainly reduce the EC of the urea industry. Furthermore, the application of green energy will be conducive to a win-win situation for both economic and environmental benefits.

Effects of Low-level Occupational Exposure to Ammonia on Hematological Parameters and Kidney Function

Background:

Many workers, particularly those working in manufacture of fertilizers, explosives, rubber, pesticides, textiles, and employees of petrochemical industries are exposed to ammonia in their workplaces. Toxic responses of hematopoietic system and kidney following occupational exposure to this chemical have not been thoroughly investigated.

Objective:

To determine the relationship between long-term occupational exposure to low levels of ammonia and hematological parameters and kidney function.

Methods:

In this cross-sectional study, 119 randomly selected, male petrochemical workers and 131 office employees (comparison group) were examined. Urine and blood samples were taken from all participants for urinalysis, complete blood count (CBC), serum calcium level, and blood urea nitrogen (BUN) and plasma creatinine. Personal, environmental, and peak ammonia exposure were also measured.

Results:

The median personal, environmental, and peak occupational exposure to ammonia were 0.23, 0.16, and 65.50 mg/m3, respectively, among the exposed group. No significant difference was observed between the exposed and unexposed participants in terms of hematological parameters and urinalysis. Conversely, calcium and BUN, while within the normal range, were significantly higher in the exposed than in the comparison group.

Conclusion:

Occupational exposure to low atmospheric concentrations of ammonia was associated with subtle, sub-clinical, pre-pathologic changes in kidney function. Possible longterm consequences and ramifications of these effects require further investigation.

Mesoscale behavior study of collector aggregations in a wet dust scrubber

In order to address the bottleneck problem of low fine-particle removal efficiency of self-excited dust scrubbers, this paper is focused on the influence of the intermittent gas-liquid two-phase flow on the mesoscale behavior of collector aggregations. The latter is investigated by the application of high-speed dynamic image technology to the self-excited dust scrubber experimental setup. The real-time-scale monitoring of the dust removal process is provided to clarify its operating mechanism at the mesoscale level. The results obtained show that particulate capturing in self-excited dust scrubber is provided by liquid droplets, liquid films/curtains, bubbles, and their aggregations. Complex spatial and temporal structures are intrinsic to each kind of collector morphology, and these are considered as the major factors controlling the dust removal mechanism of self-excited dust scrubbers. For the specific parameters of gas-liquid two-phase flow under study, the evolution patterns of particular collectors reflect the intrinsic, intermittent, and complex characteristics of the temporal structure. The intermittent initiation of the collector and the air hole formation-collapse cyclic processes provide time and space for the fine dust to escape from being trapped by the collectors. The above mesoscale experimental data provide more insight into the factors reducing the dust removal efficiency of self-excited dust scrubbers.

IMPLICATIONS

This paper focuses on the reconsideration of the capturer aggregations of self-excited dust scrubbers from the mesoscale. Complex structures in time and space scales exist in each kind of capturer morphology. With changes of operating parameters, the morphology and spatial distributions of capturers diversely change. The change of the capturer over time presents remarkable, intermittent, and complex characteristics of the temporal structure.