查看更多>>摘要：The remediation of trichloroethylene contaminated groundwater by permanganate-based in situ chemical oxidation is limited by MnO2 formation. The application of phase transfer catalyst (PTC) is a promising alternative to enhance remediation efficiency, and the alleviation of MnO2 generation is one of crucial capacities of PTC to promote oxidation. This work has emphatically elucidated the mechanism of MnO2 alleviation by PTC, as well as the effectiveness which was researched by conducting batch and sand column experiments. The results indicated that the contents of MnO2 suspended in aqueous phase and total manganese in the media were respectively decreased by 29.5% and 26.1% attributed to PTC addition. Although PTC could not be used as a chelator for Mn(III) stabilization, the generation of dissolved Mn(II) and Mn(III) was promoted by PTC for less MnO2 generation. Further studies illustrated that redox reactions would occur between dissolved Mn(II)/Mn(III) and TCE, which benefited TCE degradation. Moreover, Smaller particle size and improved colloidal stabilization of formed MnO2 were achieved by PTC to minimize MnO2 precipitation. Overall, effective alleviation of the MnO2 generation and precipitation by PTC is collectively contributed from the promotion of dissolved Mn(II) and Mn(III) and the stabilization of MnO2 formed in situ.
查看更多>>摘要：Acidogenic fermentation coupled with microalgae cultivation is a promising approach for mariculture wastewater (MW) treatment. However, the low biomass and lipid production of microalgae restrict its practical application. In this study, auxin analogues including α-naphthylacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D) and indomethacin were applied to the cultivation of Chlorella pyrenoidosa under mixotrophic condition. The effects of auxin analogues on microalgal growth, intracellular component accumulation and nutrient removal were evaluated. The optimal growth and intracellular composition accumulation of Chlorella pyrenoidosa were obtained at 2 mg L~(-1) NAA, 1 mg L~(-1) indomethacin, and 1 mg L~(-1) 2,4-D. NAA was more efficient than indomethacin and 2,4-D for lipid production, and the maximum lipid accumulation reached 52% with 2 mg L~(-1) NAA. Auxin analogues enhanced the uptake of volatile fatty acids, ammonium and phosphate from acidogenic fermentation effluent, attributed to the improvement of microalgal growth. This study provided a new insight for enhancing mariculture wastewater treatment with mixotrophic microalgae.
查看更多>>摘要：Cooking-oil fumes (COFs) from street-food stalls in night markets have adverse effects on air quality and workers. This study proposes a floor-mounted, cylindrical, movable, small-sized rotating packed bed (RPB) coupled with green surfactants in a Span and Tween mixture as an intensified chemical scrubber for COF purification. Moreover, it is used for an on-site performance evaluation of PM2.5 removal efficiency (η_(PM2.5)) in a fried-food stall. With a hydrophilic-lipophilic balance of 6 (H6) from the Span and Tween mixture, an optimal dose of 8.2 g/L is achieved for an η_(PM2.5) of 88.8 %. Except for direct interception and inertial impaction, the RPB with H6 stimulates the emulsification of COFs, which is a dominant mechanism for the range of PM_(1-2.5). By comparing the effects of scrubbing solutions of water, traditional detergent, and H6, it is found that H6 exhibits the highest emulsification effect for η_(PM2.5) with low scent and manageable foaming level. A 7-day performance evaluation for commercial operation suggests that a promising η_(PM2.5) can be reached by maintaining the concentration of H6 in the scrubbing solution. Therefore, the effectiveness of the RPB with the bio-based H6 surfactant is clearly demonstrated by the removal of PM2.5 in commercial fried-food stalls. The findings shed light on the development and application of RPB with bio-based and eco-friendly surfactants for wet scrubbing of COFs in terms of particulate-matter removal in commercial fried-food stalls.
查看更多>>摘要：Stainless steel dust and chromium containing slag are representative harmful solid wastes produced in modern iron and steel metallurgy industry. Based on the study of stainless steel dust reduction, the direct reduction process with low energy consumption and high efficiency was obtained by changing the addition amount of chromium containing slag and the conditions of reduction process system. The results show that with the addition of chromium containing slag, the basicity of raw materials decreases, the recovery of metal is improved, and the self-pulverization effect of reducing slag is improved. The optimum process conditions are as follows: the mixing ratio of stainless steel dust to chromium containing slag is 94%: 6%, the reduction temperature is 1400 °C, the reduction time is 25 min, the FC/O is 0.9, the recoveries of Fe, Cr and Ni in the reduction products are 90.5%, 90.6% and 91.2%, respectively, the grades of Fe, Cr and Ni in Fe-Cr-Ni-C alloy are 61.3%, 19.9% and 3.7%, respectively, and the contents of harmful components such as S and P are very low. The self-pulverization rate of reduction slag can reach 92.8%, and the residues of metal Fe, Cr and Ni in reduction slag are 134 ppm, 96 ppm and 129 ppm, respectively.
查看更多>>摘要：Calcium peroxide (CaO2) and persulfate (PS) dual oxidant system is an innovative in-situ chemical oxidation (ISCO) technique for the restoration of contaminated groundwater. Several field applications also confirm its efficacy in remediating the groundwater, however, published articles are rarely present. In this work, the performance of the CaO2/PS system was examined for the degradation of sulfamethoxazole (SMX) in the SMX polluted soil and water. Results indicated that SMX could be efficiently degraded with CaO2 and PS (2 g/L dosages for each oxidant) around neutral pH (7), and 95.8% pollutant removed after 36 h of reaction time. The removal efficiency of SMX improved as the concentrations of CaO2 and PS were increased. Moreover, SMX removal was significantly decreased with the increase of initial solution pH. This dual oxidant system at 30 °C was also used for the remediation of SMX (10 mg/kg) spiked soil. Soil degradation experiment was performed at 150 rpm of shaking speed using soil slurry (soil/water;; 1/1 ratio) at pH 7. Dual oxidant dosage was kept at 2 g/L CaO2 and 2 g/L PS. The results showed that this dual oxidant system is also very efficient for the antibiotics SMX degradation in the soil system. Overall, an insight knowledge and practical information gained from this work will help in the treatment of SMX contaminated soil and water as well as wastewater with CaO2/PS dual oxidant system.
查看更多>>摘要：This paper focuses on the characteristics of pressure wave generated by an active mechanical shock in leaking pipelines. A piston type pressure wave generator was designed and applied to the pipeline experimental system and a three-dimensional (3D) numerical simulation model was developed based on the k-ε turbulence model and dynamic mesh. The experimental results showed that the maximum amplitude of pressure wave was about 104.71 kPa, and the leakage intensified the attenuation of pressure wave in space and time through quantitative analysis. Based on the 3D simulations, the processes of the pressure wave generation and propagation were revealed. The amplitude of pressure wave increased linearly with the increase of the maximum velocity of mechanical shock, and the effects of leakage on the waveforms of pressure wave were observed under the dimensionless analysis. In addition, a shorter duration of mechanical shock can increase the amplitude of the pressure wave generated. The results presented in this paper will contribute to the development and application of the transient leak detection method for pipeline systems.
查看更多>>摘要：The present study reports the role of sulfur-doped graphitic carbon nitrides (S-g-C3N4) as a self- assembly corrosion inhibitor for X-65 steel in 3.5% NaCl solution enriched with CO2. The S-g-C3N4 was synthesized via simple pyrolysis and polymerization route. Detailed physiochemical characterization was carried out using XRD, Raman, FTIR, UV, and XPS analysis. Surface analysis such as FE-SEM and AFM studies reveals a uniform coating of S-g-C3N4 over the steel surface. Electrochemical techniques were adopted to investigate the efficiency of S-g-C3N4 on steel corrosion mitigation. Maximum inhibition efficiency of 98% and 94% at concentration of S-g-C3N4 (0.3 wt%) for polarization and impedance methods were achieved. Also, the DFT and MD simulation studies evidenced that S-g-C3N4 forms a protective layer over the steel surface. The excellent inhibition efficiency of the S-g-C3N4 is due to the presence of sulfur heteroatom thus has more affinity towards steel surface. This sulfur doped g-C3N4 could open up new opportunities in corrosion and materials protection area.
Prince Chapman AgyemanKingsley JOHNNdiye Michael Kebonye
18页
查看更多>>摘要：A resilient environment is essential for society's long-term viability. Receptor models have evolved into an excellent tool for detecting pollution sources and evaluating each source's empirical contributions based on ecological datasets. One hundred and fifteen soil sample were collected from the district of Frydek Mistek in the Czech Republic and the concentration of arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb)and zinc (Zn) measured inductively coupled plasma-optical emission spectrometry. The results suggested that the hybridized receptor models ER-PMF and PMF identified the following geogenic, steel industries, vehicular traffic, and agro-based activities such as pesticide and fertilizer applications as the primary sources in the source distribution. The ER-PMF source pollution identification efficiency ranged from R2 0.872-0.970, RMSE 0.128-17.344 and MAE 0.085-10.388, whereas the PMF R2 ranged from 0.883 to 0.960, RMSE 0.246-79.003 and MAE 0.145-49.925. The overall assessment of the efficiency of the receptor models suggests that the ER-PMF appears to yield more efficient results in pollution source identification compared to PMF. The PTEs mapping using geographical weighted regression (GWR) and a hybridized regression approach, geographical weighted regression cokriging (GWRCoK), revealed that GWRCoK had a higher goodness of fit in the spatial prediction maps than GWR. According to Hakanson's risk index classification, the ecological risk level in the study area was moderate to high (risk level = 51 observed locations out of 115, or 44.35%);; however, Chen's risk index reclassification indicated that the toxicity level in the study area was moderate to extremely high (risk level = 113 observed locations out of 115, or 98.26%). However, the uncertainty assessment results indicated drat the DISP interval ratio of the hybridized ER-PMF model was lower than that of the parent PMF model. However, it was clear that the random error that could occur in the DISP based on the DISP interval ratio was likely to be lower in the ER-PMF receptor model than in the parent model. The assessment of PTEs in soil has been widely published, but this study recommends using a pollution assessment-based receptor model (ER-PMF), which has been shown to be reliable and practical in estimating distribution sources.
Ali Reza Solaimany NazarNegin EntezamiMehrdad Farhadian
14页
查看更多>>摘要：A Bi2O3/ZIF-67 heterostructure was synthesized as a novel and highly active photocatalyst by the hydrothermal method. The as-synthesized catalysts were identified by XRD, SEM, EDX, FTIR, TEM, UV-Vis DRS, BET, and PL analyses. The two-component composite showed a significant improvement in photoactivity compared to Bi2O3 and pristine ZIF-67 due to its unique characteristics such as increased specific surface area and visible light adsorption, as well as reduced bandgap and recombination rate of electron-hole. The optimum values of the processing variables for the contaminant degradation efficiency were determined for photocatalytic process (catalyst concentration= 0.4 g/L, pH= 9, tetracycline (TC) initial concentration= 20 mg/L, and time= 120 min) and capacitive deionization system (CDI) (L=5 mm, voltage=1.8 V, and TC concentration=20 mg/l) and the maximum pollutant removal efficiency under optimal conditions for catalyst adsorption, photocatalytic process, and CDI systems were obtained 12%, 84% and 69%, respectively. The identification of a kinetic study confirmed that the TC removal followed the pseudo-first-order model. According to kinetic studies, the combination of photocatalysis and CDI system (PCS) has a significant effect on the efficiency of the contaminant removal, and the reaction rate constant is increased by about 1.5 and 2.4 times compared to the photodegradation process and the CDI system, respectively. As the results show, the PCS system is a promising way of removing contaminants and dramatically increasing the removal efficiency. Experimental results showed a great chemical stability and reusability of the photocatalyst and the graphite electrode after five cyclic usage.
Ahmed A. HassanAhmed E. ElwardanyShinichi Ookawara
20页
查看更多>>摘要：Energy, exergy, economic and environmental assessment is performed for an integrated hybrid solar system powering a multigeneration system. The proposed multigeneration system is integrated parallel/series configurations of organic Rankine cycle (ORC) unit and adsorption chiller under weather conditions of Alexandria-Egypt. The solar subsystem comprises photovoltaic/thermal collectors (PVT) connected in parallel arrangement with evacuated tube solar collectors (ET). The system output aims to provide annual electricity requirements via PVT collectors and the ORC unit and supply cooling requirements during summer via an adsorption chiller for a small building. The hot water output of the solar system is used to drive the ORC unit and adsorption chiller in four configurations;; (Conf-1) hot water drives the adsorption chiller, then its output hot water runs the ORC unit (series), (Conf-2) it drives the ORC first, then the adsorption chiller (series), (Conf-3) hot water is divided between adsorption and ORC (parallel), and (Conf-4) hot water drives only adsorption without using ORC unit. Moreover, the impact of the area ratio of the PVT to ET collector and the ORC working fluid and its flow rate on the system performance is investigated. A complete mathematical model is developed for the system components and solved using MATLAB software. The results show that Conf-4 has the best cooling production performance with an average value of 9.6 kW during the summer months and energy efficiency with an average value of 0.3 during August. Conf-1 is the best performing configuration in cooling production of about 5.6 kW average cooling capacity compared to Conf-2 and Conf-3. In contrast, Conf-2 has the best ORC unit performance with a maximum output of 1.2 kW on a typical day in July. Increasing the PVT collector area in the solar configuration negatively affects cooling production but increases electricity production, which augments the system's overall exergy and energy efficiencies. R600 is the best ORC working fluid compared to R290 and R134a in terms of average ORC power production of about 0.72 kW compared to 0.63 kW for R290 and 0.39 kW for R134a. Conf-1 is found to have the best energy savings of about 50.8 MWh/year and thus the best emissions of approximately 10.06 equivalent ton_(CO2) per year. The system Payback period is about 9.8, 9.95, 9.9, and 8.45 years for Conf-1 to Conf-4, respectively, proving the system's economic feasibility.
NSTL