scholarly journals NOxRemoval from Simulated Marine Exhaust Gas by Wet Scrubbing Using NaClO Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Zhitao Han ◽  
Bojun Liu ◽  
Shaolong Yang ◽  
Xinxiang Pan ◽  
Zhijun Yan
Keyword(s):  
Removal Efficiency ◽  
Reaction Mechanisms ◽  
Complete Removal ◽  
Initial Solution ◽  
Exhaust Gas ◽  
Solution Ph ◽  
Wet Scrubbing ◽  
Initial Ph

The experiments were performed in a lab-scale countercurrent spraying reactor to study the NOxremoval from simulated gas stream by cyclic scrubbing using NaClO solution. The effects of NaClO concentration, initial solution pH, coexisting gases (5% CO2and 13% O2), NOxconcentration, SO2concentration, and absorbent temperature on NOxremoval efficiency were investigated in regard to marine exhaust gas. When NaClO concentration was higher than 0.05 M and initial solution pH was below 8, NOxremoval efficiency was relatively stable and it was higher than 60%. The coexisting CO2(5%) had little effect on NOxremoval efficiency, but the outlet CO2concentration decreased slowly with the initial pH increasing from 6 to 8. A complete removal of SO2and NO could be achieved simultaneously at 293 K, initial pH of 6, and NaClO concentration of 0.05 M, while the outlet NO2concentration increased slightly with the increase of inlet SO2concentration. NOxremoval efficiency increased slightly with the increase of absorbent temperature. The relevant reaction mechanisms for the oxidation and absorption of NO with NaClO were also discussed. The results indicated that it was of great potential for NOxremoval from marine exhaust gas by wet scrubbing using NaClO solution.

scholarly journals Chromium and cadmium removal from synthetic wastewater by Electrocoagulation process

2020 ◽  
Vol 9 (2) ◽  
pp. 375-382
Keyword(s):  
Removal Efficiency ◽  
Current Density ◽  
Initial Temperature ◽  
Complete Removal ◽  
Synthetic Wastewater ◽  
Cadmium Removal ◽  
Solution Ph ◽  
Initial Concentration ◽  
Initial Ph ◽  
Electrocoagulation Process

Electrocoagulation (EC) is one of the efficient electrochemical approaches for industrial wastewater treatment. The present work aims to reach optimum conditions for achieving simultaneous removal of chromium and cadmium ions from synthetic wastewater by EC through assessment of different parameters like electrodes material, electrode configuration, initial pH, current density, initial temperature, and initial contaminate concentration. In addition, a comparison between chemical coagulation and EC efficiency for Chromium and cadmium removal was presented. Results showed that the (Fe-Al), an anode and cathode, achieved better removal efficiency than other electrodes configurations (Fe-Fe / Al-Fe / Al- Al). Also, the increase of initial temperature and current density enhanced the removal efficiency. In contrast, the increase in the initial concentration reduced the removal efficiency. The complete removal of Chromium achieved through the use of Fe-Al electrodes and current density was 12.50 mA/cm2 with solution pH of 5.8, temperature was 25oC and an initial concentration of 280 mg/L. On the other hand, Cadmium’s complete removal was achieved through the use of Fe-Allectrodes, at pH of 5.8, applied current 1.4 A and 60oC. Therefore, EC was proved to be better approach than conventional coagulation in case of treatment of wastewater containing different types of heavy metals ions with high initial concentrations.

scholarly journals NO Removal from Simulated Diesel Engine Exhaust Gas by Cyclic Scrubbing Using NaClO2 Solution in a Rotating Packed Bed Reactor

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Han Zhitao ◽  
Gao Yu ◽  
Yang Shaolong ◽  
Dong Jingming ◽  
Pan Xinxiang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Rotational Speed ◽  
Complete Removal ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Exhaust Gas ◽  
Solution Ph ◽  
No Removal ◽  
Rotating Packed Bed ◽  
Gas Ratio

Experiments were conducted to remove NO from simulated flue gas in a rotating packed bed (RPB) reactor with NaClO2 as wet scrubbing oxidant and diesel exhaust gas as carrier gas. The effects of various operating parameters (rotational speed, solution pH, NaClO2 concentration, liquid-gas ratio, and NO and SO2 concentrations) on NO removal performance were investigated preliminarily. The results showed that with the increase of rotational speed, oxidant concentration, and liquid-gas ratio, NO removal efficiency increased obviously. NO removal efficiency increased largely with the decrease of solution pH, and a complete removal of NO could be attained at pH 4. NO concentration imposed little effect on NO removal efficiency while coexisting SO2 in exhaust gas could enhance NOx removal greatly.

Dependence of Stability of Sr5(AsO4)3OH on pH Value

2014 ◽  
Vol 692 ◽  
pp. 229-233
Author(s):  
Yan Hua Huang ◽  
Zong Ning Li ◽  
Hui Qin ◽  
Zong Qiang Zhu ◽  
Yi Nian Zhu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Ph Value ◽  
Reaction System ◽  
Initial Solution ◽  
Alkaline Solutions ◽  
Solution Ph ◽  
Batch Dissolution ◽  
Initial Ph

The object of this work was to determine the solubility and stability of the synthetic Sr5(AsO4)3OH solid solution at 25°C and the different initial pHs (pH at 2, 6 and 9) by batch dissolution experiments. The results indicated that with the initial pH value of 2, 6 and 9, the reaction system reached equilibrium after 2880h, and by that time the pH value of the solution reached, 7.90, 8.74 and 8.27 respectively. The concentration of strontium and arsenic in the initial solution pH at 2 are higher than that of solutions pH at 6 and 9. While the concentration of strontium in neutral or alkaline solutions is low and stays unchanged.

scholarly journals Simultaneous Removal of NO, SO2 and Hg0 with the WDRMRS

2021 ◽  
Author(s):  
Mingqiang Deng ◽  
Zhengguo Xiao ◽  
Dengxin Li ◽  
Qiaoling Zhu ◽  
Qin Chen ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Flue Gas ◽  
Critical Role ◽  
Urea Solution ◽  
Simultaneous Removal ◽  
Solution Ph ◽  
System A ◽  
Liquid Dispersion ◽  
Initial Ph ◽  
Pollutants Removal

Abstract Micro-nanobubbles can spontaneously generate hydroxyl free radicals (*OH). Urea is a cheap reductant and can react with NOx species, and their products are nontoxic and harmless N2, CO2 and H2O. In this study, a Wet Direct Recycling Micro-nanobubble Flue Gas Multi-pollutants Removal System (WDRMRS) was developed for the simultaneous removal of NO, SO2 and Hg0. In this system, a micro-nanobubble generator (MNBG) was used to produce a micro-nanobubble gas-liquid dispersion system (MNBGLS) through recycling the urea solution from the reactor and the simulated flue gas composed of N2, NO, SO2 and Hg0. The MNBGLS, which has a large gas-liquid dispersion interface, was recycled continuously from the MNBG to the reactor, thus achieving cyclic absorption of various pollutants. All of the investigated parameters, including the initial pH and temperature of the absorbent as well as the concentrations of urea, NO and SO2 had significant effects on the NO removal efficiency but did not significantly affect the SO2 removal efficiency, whereas only the initial solution pH and NO concentration affected the Hg0 removal efficiency. The analysis results of the reaction mechanism showed that played a critical role in the removal of various pollutants. After the treatment by this system, the main removal products were HgO sediment, and which could be easily recycled.

Experiment on Simultaneous Absorption of NO and SO2 from Sintering Flue Gas by Oxidizing Agents of KMnO4/NaClO

2014 ◽  
Vol 12 (1) ◽  
pp. 539-547 ◽  
Author(s):  
Ying Li ◽  
Wenqi Zhong ◽  
Jing Ju ◽  
Tiancai Wang ◽  
Fei Liu
Keyword(s):  
Removal Efficiency ◽  
Flue Gas ◽  
Initial Solution ◽  
Molar Ratio ◽  
Gas Temperature ◽  
Inlet Concentration ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Simultaneous Absorption ◽  
Spray Absorption

Abstract A complex oxidizing agent combination made up of KMnO4 and NaClO was used to investigate the simultaneous absorption of NO and SO2 from sintering flue gas in a spray absorption tower on a laboratory scale. The effects of various operating parameters, i.e. initial gas temperature (Tg), initial solution pH, molar ratio of NaClO/KMnO4 (M), initial NO inlet concentration (CN) and SO2 initial inlet concentration (CS), were systematically investigated in the experiments. The results showed that the removal efficiency of SO2 was slightly affected by the reaction conditions and remained stable above 98%; however, the removal efficiency of NO was significantly influenced. It presented different trends with the reaction condition changed. The most optimal experimental conditions for simultaneous removal of NO and SO2 were found to be initial solution pH=5.5, Tg=50°C, M=3; in this case the average removal efficiencies of NO and SO2 could reach 98.8 and 70.9%, respectively.

scholarly journals The Effect of Fe(II), Fe(III), Al(III), Ca(II) and Mg(II) on Electrocoagulation of As(V)

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 215
Author(s):  
Niels Michiel Moed ◽  
Young Ku
Keyword(s):  
Removal Efficiency ◽  
Complete Removal ◽  
Metal Chlorides ◽  
Initial Ph

The interaction between metal chlorides and electrocoagulation was tested. Precipitation of As(V) was found to be optimal at pH 4.9 using FeCl2, 2.6 for FeCl3, 3.8 using AlCl3, 11.6 using CaCl2 and 8.6 using MgCl2. As(V) removal through electrocoagulation went down as initial pH (pHi) of the solution increased. Addition of FeCl2 increased removal of As(V) at all pHi but was not able to achieve full removal at pHi 7. FeCl3 had a similar effect but a lower Fe(III) concentration of 30 mg/L was not sufficient for full removal at pHi 5 either. AlCl3 addition reduced removal efficiency at pHi 3 but removed all or most As(V) through precipitation at pHi 5 and 7, with complete removal followed through electrocoagulation. The addition of CaCl2 and MgCl2 resulted in nearly identical behavior. Addition of either at pHi 3 had no influence, but at pHi 5 and 7 caused complete removal to take place.

Application of iron-coated sand on the treatment of toxic metals

2004 ◽  
Vol 4 (5-6) ◽  
pp. 335-341 ◽  
Author(s):  
Jae-Kyu Yang ◽  
Yoon-Young Chang ◽  
Sung-Il Lee ◽  
Hyung-Jin Choi ◽  
Seung-Mok Lee
Keyword(s):  
Heavy Metals ◽  
Selective Adsorption ◽  
Complete Removal ◽  
Batch Adsorption ◽  
Column Experiments ◽  
Adsorption Behaviour ◽  
Optimum Amount ◽  
Initial Ph ◽  
New Treatment ◽  
Coated Sand

Iron-coated sand (ICS) prepared by using FeCl3 and Joomoonjin sand widely used in Korea was used in this study. In batch adsorption kinetics, As(V) adsorption onto ICS was completed within 20 minutes, while adsorption of Pb(II), Cd(II), and Cu(II) onto ICS was slower than that of As(V) and strongly depended on initial pH. At pH 3.5, ICS showed a selective adsorption of Pb(II) compared to Cd( II) and Cu(II) . However, above pH 4.5, near complete removal of Pb(II), Cd(II), and Cu(II) was observed through adsorption or precipitation depending on pH. As(V) adsorption onto ICS occurred through an anionic-type and followed a Langmuir-type adsorption behaviour. In column experiments, pH was identified as an important parameter in the breakthrough of As(V). As(V) breakthrough at pH 4.5 was much slower than at pH 9 due to a strong chemical bonding between As(V) and ICS as similar with batch adsorption behaviour. With variation of ICS amounts, the optimum amount of ICS at pH 4.5 was identified as 5.0 grams in this research. At this condition, ICS could be used to treat 200 mg of As(V) with 1 kg of ICS until 50 ppb of As(V) appeared in the effluent. In this research, as a new treatment system, ICS can be potentially used to treat As(V) and cationic heavy metals.

scholarly journals Efficient Sequestration of Hexavalent Chromium by Graphene-Based Nanoscale Zero-Valent Iron Composite Coupled with Ultrasonic Pretreatment

2021 ◽  
Vol 18 (11) ◽  
pp. 5921
Author(s):  
Haiyan Song ◽  
Wei Liu ◽  
Fansheng Meng ◽  
Qi Yang ◽  
Niandong Guo
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Inhibitory Effect ◽  
Ultrasonic Cavitation ◽  
Zero Valent Iron ◽  
Ultrasonic Pretreatment ◽  
Nanoscale Zero Valent Iron ◽  
Passivation Layers ◽  
Initial Ph ◽  
Two Phases

Nanoscale zero-valent iron (nZVI) has attracted considerable attention for its potential to sequestrate and immobilize heavy metals such as Cr(VI) from an aqueous solution. However, nZVI can be easily oxidized and agglomerate, which strongly affects the removal efficiency. In this study, graphene-based nZVI (nZVI/rGO) composites coupled with ultrasonic (US) pretreatment were studied to solve the above problems and conduct the experiments of Cr(VI) removal from an aqueous solution. SEM-EDS, BET, XRD, and XPS were performed to analyze the morphology and structures of the composites. The findings showed that the removal efficiency of Cr(VI) in 30 min was increased from 45.84% on nZVI to 78.01% on nZVI/rGO and the removal process performed coupled with ultrasonic pretreatment could greatly shorten the reaction time to 15 min. Influencing factors such as the initial pH, temperature, initial Cr(VI) concentration, and co-existing anions were studied. The results showed that the initial pH was a principal factor. The presence of HPO42−, NO3−, and Cl− had a strong inhibitory effect on this process, while the presence of SO42− promoted the reactivity of nZVI/rGO. Combined with the above results, the process of Cr(VI) removal in US-nZVI/rGO system consisted of two phases: (1) The initial stage is dominated by solution reaction. Cr(VI) was reduced in the solution by Fe2+ caused by ultrasonic cavitation. (2) In the following processes, adsorption, reduction, and coprecipitation coexisted. The addition of rGO enhanced electron transportability weakened the influence of passivation layers and improved the dispersion of nZVI particles. Ultrasonic cavitation caused pores and corrosion at the passivation layers and fresh Fe0 core was exposed, which improved the reactivity of the composites.

Effects of operational parameters on defluoridation efficiency using electrocoagulation process

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
M. Behbahani ◽  
M.R. Alavi Moghaddam ◽  
M. Arami
Keyword(s):  
Reaction Time ◽  
Anode Material ◽  
Removal Efficiency ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Operational Parameters ◽  
Applied Current ◽  
Initial Ph ◽  
Electrocoagulation Process ◽  
Electrode Connection

The aim of this study is to examine the effect of operational parameters on fluoride removal using electrocoagulation method. For this purpose, various operational parameters including initial pH, initial fluoride concentration, applied current, reaction time, electrode connection mode, anode material, electrolyte salt, electrolyte concentration, number of electrodes and interelectrode distance were investigated. The highest defluoridation efficiency achieved at initial pH 6. In the case of initial fluoride concentration, maximum removal efficiency (98.5%) obtained at concentration of 25mg/l. The increase of applied current and reaction time improved defluoridation efficiency up to 99%. The difference of fluoride removal efficiencies between monopolar and bipolar series and monopolar parallel were significant, especially at reaction time of 5 min. When aluminum used as anode material, higher removal efficiency (98.5%) achieved compared to that of iron anode (67.7%). The best electrolyte salt was NaCl with the maximum defluoridation efficiency of 98.5% compared to KNO3 and Na2SO4. The increase of NaCl had no effect on defluoridation efficiency. Number of electrodes had little effect on the amounts of Al3+ ions released in the solution and as a result defluoridation efficiency. Almost the same fluoride removal efficiency obtained for different interelectrode distances.

Sign in / Sign up

Export Citation Format

Share Document