Search

Hydroponic wastewater recovery provides a green alternative to chemical fertilizers by recycling nutrients, yet transitioning to closed systems introduces problems such as pathogen proliferation and high sterilization costs. These challenges, along with the need for regular water analysis to correct nutrient imbalances, can hinder crop growth and increase expenses. However, hydroponic wastewater is also beneficial for capturing harmful emissions like CO2, NOx, and NH3, thanks to its rich mineral content. As it reacts with air pollutants, it produces compounds like Ca(NO3)2 and NH4NO3, turning pollutants into useful fertilizers. This study designed a novel hydroponic wastewater recovery process for CO2, NOx, and NH3 utilization from crop residue burning gas. through the following procedures: (1) ion separation of hydroponic wastewater, (2) NOx capture and utilization using precipitated Ca(OH)2, (3) NH3 capture and utilization using separated NO3− and SO42−, and (4) CO2 capture and utilization using KOH, Ca(OH)2 and Mg(OH)2. A process model was developed, and the economic feasibility of the proposed system was determined by calculating the total annualized cost. The result shows that approximately 85% of NOx, 99% of CO2, and 99% of NH3 were captured and utilized. Importantly, the total annualized cost of the system could decrease by 70% compared with that of the base process. [ABSTRACT FROM AUTHOR]

Although ethylene (C2H4) is one of the most critical chemicals used as a feedstock in artificial plastic chemistry fields, it is challenging to obtain high‐purity C2H4 gas without any trace ethane (C2H6) by the oil cracking process. Adsorptive separation using C2H6‐selective adsorbents is beneficial because it directly produces high‐purity C2H4 in a single step. Herein, Ni(IN)2 (HIN = isonicotinic acid) is computationally discovered as a promising adsorbent with the assistance of the multiscale high‐throughput computational screening workflow and Computation‐Ready, Experimental (CoRE) metal–organic framework (MOF) 2019 database. Ni(IN)2 is subsequently synthesized and tested to show the ideal adsorbed solution theory (IAST) selectivity of 2.45 at 1 bar for a C2H6/C2H4 mixture (1:15), which is one of the top‐performing selectivity values reported for C2H6‐selective MOFs as well as excellent recyclability, suggesting that this material is a promising C2H6‐selective adsorbent. Process‐level simulation results based on experimental isotherms demonstrate that the material is one of the top materials reported to date for ethane/ethylene separation under the conditions considered in this work. [ABSTRACT FROM AUTHOR]

Shadowgraphy-based image processing studied in the literature on multiphase processes has led to meaningful advances in mass transfer enhancement via interfacial area enlargement. However, the industrial applications of shadowgraphy have been limited due to the requirement of an additional light source at specific locations. To overcome this limitation, in this study, a new bubble size measurement technique in low-light conditions is proposed. The technique uses reflected LED image on the bubble surface to estimate the bubble size in low-light conditions and includes a newly derived measurement correlation model, which was validated with lab-scale experimental data. Furthermore, the proposed model was applied to industrial-scale bubble systems for hydrogen fluoride (HF) removal. Using the bubble properties identified through analysis, the overall mass transfer coefficient (OMTC) was determined as an indicator of HF mass transfer enhancement. The optimal conditions for HF mass transfer were determined by identifying the system with the highest OMTC. By manipulating the pressure difference and flow rate, OMTC was increased by ∼78% of the base case. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] At public bus stops, NO X pollutants discharged by regularly stopping buses quickly accumulate, exposing waiting passengers to high levels of air pollutants, which creates a threat to public health. The environmental protection agency (EPA) presents air quality standards for NO X , a significant pollutant that causes lung diseases such as asthma when exposed to the human body. To handle this problem, air purification systems are installed inside bus stops in many public places. However, it is challenging to maintain a low concentration of NO X inside public bus stops due to the persistent inflow of bus exhaust gas. Therefore, it is crucial to design an optimal location for an air purification system to meet air environment standards for respiratory areas. This study proposed a computational fluid dynamics (CFD)-based optimal installation strategy for an air purification system to minimize NO X exposure inside a public bus stop. The CFD model was developed to numerically analyze NO 2 exposure with the actual design value for a public bus stop in Ulsan, South Korea. The local NO 2 concentration was evaluated in the human breathing zone. The case study was performed according to the locations of the inlet and outlet of the air purification system. A transient CFD simulation was performed to analyze the effect of the air purification system on pollutants generated from the stationary bus by time flow in various cases. NO 2 concentration and exposure reduction effectiveness (ERE) were analyzed and compared for each case in the breathing zone. In the optimal case, the ERE of NO 2 was confirmed to be 35.9 %, and the NO 2 concentration according to the air quality standards of EPA could be maintained at 0.1 ppm or less. The theoretical framework proposed in this study can be generalized to design air purification systems for general external facilities. [ABSTRACT FROM AUTHOR]