The efficiency and mechanism of the degradation of nitrobenzene in aqueous solution by O3/H2O2

2006 ◽  
Vol 6 (4) ◽  
pp. 153-162 ◽  
Author(s):  
J. Shen ◽  
Z. Chen ◽  
X. Li ◽  
F. Qi ◽  
M. Ye
Keyword(s):  
Aqueous Solution ◽  
Carbonyl Compounds ◽  
Phenyl Ring ◽  
Ph Value ◽  
Reaction Pathway ◽  
Removal Rate ◽  
Inorganic Compounds ◽  
Catalytic Ozonation ◽  
Aliphatic Compounds ◽  
Effects Of Ph

Selecting nitrobenzene (NB) as the model pollutant, this paper investigated the efficiency and mechanism of the degradation of NB in aqueous solution by O3/H2O2. The effects of pH value, H2O2 dose and the inhibitor or accelerant of •OH on the removal rate of NB were studied. H2O2 could obviously improve the ozonation decay rate of NB below pH 7. When H2O2 dose increased from 1.0 mg/L to 4.0 mg/L, the removal rate of NB was remarkably enhanced. However, as H2O2 dose increased from 4.0 mg/L to 20 mg/L, the removal efficiency of NB decreased. Different masses of H2O2 were yielded in different reaction phases of the single ozonation system. Both single ozonation systems and H2O2-catalysed ozonation could not observably reduce the TOC. During the process of NB degradation, organonitrogen was almost completely converted to nitrate and the pH value reduced significantly. Results of HPLC-MS and GC-MS showed that the main intermediate products were phenolic compounds and carbonyl compounds. Finally, a possible reaction pathway of the catalytic ozonation of NB is proposed. It had been found that the catalytic ozonation of NB could be divided into two steps. First, hydroxyl radical attacked phenyl ring, and then the ring opened, forming into various aliphatic compounds or being mineralized to inorganic compounds.

scholarly journals Adsorption of aquatic Cd2+ using a combination of bacteria and modified carbon fiber

2017 ◽  
Vol 36 (3-4) ◽  
pp. 857-871 ◽  
Author(s):  
Chao Xue ◽  
Peishi Qi ◽  
Yunzhi Liu
Keyword(s):  
Aqueous Solution ◽  
Composite Material ◽  
Carbon Fiber ◽  
Active Sites ◽  
Ph Value ◽  
Removal Rate ◽  
Sorption Process ◽  
Acid Sites ◽  
Heterogeneous Distribution ◽  
Carbon Fiber Material

Batch experiments were conducted to investigate the capacity and mechanisms for adsorbing Cd2+ from aqueous solutions by the composite material. The composite material was manufactured with Plesiomonas shigelloides strain H5 and modified polyacrylonitrile-based carbon fiber. Experimental results showed that the surface areas of modified polyacrylonitrile-based carbon fiber increased by 58.54% and pore width increased by 40.19% compared with unmodified polyacrylonitrile-based carbon fiber. Boehm’s titration results show the surface acid sites of composite material were increased by 712% compared with unmodified polyacrylonitrile-based carbon fiber. The field emission scanning electron microscope results show P. shigelloides H5 can be grown on the surface of modified polyacrylonitrile-based carbon fiber closely. The equilibrium removal rate and sorption quantity of composite material were 71.56% and 7.126 mg g−1, respectively. With the pH value of aqueous solution increased, the removal rate of Cd2+ ions was also increased, but the change of temperature and ionic strength had no significant effect on the removal rate. Furthermore, the results showed the whole sorption process was a good fit to Lagergren pseudo-second-order model and Freundlich isotherms model. Therefore, the results infer that there was a heterogeneous distribution of active sites, and then the sorption process was chemical adsorption and multilayer adsorption. In a word, microbial composite carbon fiber material can adsorb Cd2+ ions from aqueous solution effectively, which might be helpful in wastewater treatment in the future.

A Study of Fenton’s Oxidation Pretreatment on Dye Wastewater Containing Acetic Acid

2014 ◽  
Vol 1044-1045 ◽  
pp. 215-218
Author(s):  
Xian Huan Qiu ◽  
Hai Yu ◽  
Peng Fei Deng
Keyword(s):  
Acetic Acid ◽  
Processing Time ◽  
Ph Value ◽  
Removal Rate ◽  
Cod Removal ◽  
Dye Wastewater ◽  
Fenton’S Oxidation ◽  
Effects Of Ph ◽  
Cod Removal Rate ◽  
Fenton's Oxidation

In the presence of acetic acid, the effects of pH, processing time, addition of Fe2+ and H2O2 on dye wastewater treatment were studied. Experimental results showed that in the presence of acetic acid, when the pH value was 4, the processing time was 30.0min, addition of ferrous sulfate was 4.8g/L, and addition of hydrogen peroxide was 56mL/L, the treatment effect was the best, COD removal rate reached 51.0%. Further studied of the effect of the presence of acetic acid on Fenton’s oxidation of dye wastewater, the results showed that without of acetic acid, the COD removal rate was higher than that with acetic acid. And the effect of Fenton's reagent on oxidation of dye substances was interfered by the presence of acetic acid.

scholarly journals Mn/sepiolite as the heterogeneous ozonation catalysts applied to the advanced treatment of regenerated-papermaking wastewater

2016 ◽  
Vol 75 (5) ◽  
pp. 1025-1033 ◽  
Author(s):  
Zheng Cheng ◽  
Rendang Yang ◽  
Yang Wang
Keyword(s):  
Reaction Pathway ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Catalytic Ozonation ◽  
Treated Wastewater ◽  
Precipitation Method ◽  
Advanced Treatment ◽  
Heterogeneous Catalytic ◽  
High Removal Rate ◽  
Papermaking Wastewater

Herein a Mn-deposited sepiolite catalyst was obtained through a facile co-precipitation method, and then used as the heterogeneous ozonation catalysts applied to the tertiary treatment of regenerated-papermaking wastewater. During the process, the as-prepared catalyst was endowed with higher Brunauer–Emmett–Teller specific surface area of 412.3 m2/g compared to 124.6 m2/g of the natural sepiolite. Hence, in the adsorption of methylene blue, the as-prepared catalyst was observed with a very high removal rate of 96.2% although a little lower than the modified sepiolite of 97.5% in 100 min. And for practical application, the catalyst was used for treating the effluent from regenerated-papermaking industry, via a heterogeneous catalytic ozonation process. Consequently, the highest color removal rate of 99.5%, and the highest chemical oxygen demand (COD) removal efficiency of 73.4% were achieved in 20 and 30 min, respectively. As a result, the treated wastewater was more biodegradable and less toxic; the biochemical oxygen demand (BOD5)/COD value could reach 0.41. Moreover, the catalyst showed superior stability at successive ozonation runs. The main possible reaction pathway is also presented. The results indicate that catalytic ozonation was proved to be effective when Mn/sepiolite was used as catalysts applied to the advanced treatment of regenerated-papermaking wastewater.

Adsorption of Aqueous Carbon Tetrachloride by a Novel TCAS-Loaded Resin

2013 ◽  
Vol 743-744 ◽  
pp. 702-705
Author(s):  
Yong Biao Peng ◽  
Xiao Jun Hu ◽  
Hao Wu ◽  
Xin He
Keyword(s):  
Aqueous Solution ◽  
Carbon Tetrachloride ◽  
Adsorption Mechanism ◽  
Exchange Resin ◽  
Ph Value ◽  
Anion Exchange Resin ◽  
Operating Temperature ◽  
Removal Rate ◽  
Static Tests ◽  
Loaded Resin

Through the method of the static tests, the removal rate of aqueous carbon tetrachloride onto a new TCAS-loaded resin was researched. This TCAS-loaded resin was made of a novel supramolecular acceptor compound named thiacalix [arenetetrasulfonate (TCAS) and anion exchange resin, and the adsorption mechanism was discussed preliminarily. The results of adsorption indicated that the pH value was an important factor for the removal of carbon tetrachloride and it would be better for the adsorption if the pH value was greater than 6. The operating temperature should be controlled in 5 to 15°C for the adsorption of carbon tetrachloride onto TCAS-loaded resin while the removal rate decreased with the temperature increasing and the best time for reaction was 40min. The removal rate of carbon tetrachloride in aqueous solution was better when 25mL aqueous solution of carbon tetrachloride (1.0mg/L) was adsorbed by 0.5g TCAS-loaded resin. The carbon tetrachloride can be resolving and TCAS-loaded resin can be reused.

Study on Treatment of Cr (VI)-Containing Wastewater with Nitric Acid Modified Activated Carbon

2011 ◽  
Vol 413 ◽  
pp. 38-41
Author(s):  
Xiu Ling Song ◽  
Hui Qian
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Nitric Acid ◽  
Ph Value ◽  
Removal Rate ◽  
Freundlich Isotherm ◽  
Exchange Capacity ◽  
Modified Activated Carbon ◽  
Exchange Adsorption ◽  
Adsorption Curve

After activated carbon is oxidized and modified with nitric acid (1:1), its cation exchange capacity can amount to 1.840 mmol • g-1. The modified activated carbon is used as adsorbent for the treatment of Cr (Ⅵ)-containing wastewater at room temperature, and its removal mechanism is discussed in this paper. It is shown that: when the pH value of the aqueous solution being 2.5-3.0;the adsorption time being 3.0h, the removal rate of Cr (Ⅵ) in the aqueous solution can reach 97% and its adsorption capacity can amount to 45.66 mg • g-1. From the results, it can be also seen that the adsorption curve to chromium in wastewater by the modified activated carbon better meets the Freundlich isotherm, and ion exchange adsorption mainly does its work.

Study on Thiourea Dioxide’s Reducing Capacity and its Reactivity with Reactive Dyes

2011 ◽  
Vol 396-398 ◽  
pp. 1174-1179 ◽  
Author(s):  
Lan Zhou ◽  
Xiao Yun Liu ◽  
Jian Zhong Shao ◽  
Ya Ni Chen
Keyword(s):  
Aqueous Solution ◽  
Reduction Potential ◽  
Ph Value ◽  
Reactive Dyes ◽  
Potential Change ◽  
Analysis Method ◽  
Potential Analysis ◽  
Thiourea Dioxide ◽  
Effects Of Ph ◽  
Reducing Capacity

In this paper, potential analysis method was applied to study the effects of pH value and temperature on potential and reducing capacity of thiourea dioxide, and the reactivity between thiourea dioxide and reactive dyes as ground shade dyes under simulated printing steaming conditions in aqueous solution was also investigated. The results showed that thiourea dioxide’s reduction potential increased with the rise of pH value and temperature. when temperature was lower than 60 °C, thiourea dioxide had low reactivity with reactive dyes as ground shade dyes, and when temperature was up to 80 °C, thiourea dioxide began to break reactive dyes, which was in accordance with the reduction potential change rule of thiourea dioxide along with temperature.

Application of a novel quaternized ammonium poly(vinyl alcohol)-based hybrid anion exchange membrane for the removal of Cr(VI) from wastewater

2014 ◽  
Vol 70 (10) ◽  
pp. 1602-1609 ◽  
Author(s):  
Rui Dong ◽  
Jianxun Zhang ◽  
Bingqian Zhou ◽  
Jian Zhou
Keyword(s):  
Aqueous Solution ◽  
Anion Exchange ◽  
Vinyl Alcohol ◽  
Ph Value ◽  
Removal Rate ◽  
Poly Vinyl Alcohol ◽  
Anion Exchange Membranes ◽  
Hybrid Membranes ◽  
Adsorption Model ◽  
Adsorption Amount

Two quaternized ammonium poly(vinyl alcohol) (QPVA)-based hybrid anion exchange membranes were successfully fabricated by using sol–gel method. The mass ratios of QPVA aqueous solution to polydimethyl allyl chloride (PDADMAC) aqueous solution were 4:1 and 2:1, then 10 wt% tetraethyl orthosilicate (TEOS) was added. The obtained membranes were separately designated as QPVA/0.25PDADMAC/0.1TEOSm and QPVA/0.5PDADMAC/0.1TEOSm. The properties for the adsorption removal of Cr(VI) and the effect on the Cr(VI) saturation adsorption amount and removal rate were investigated. Results indicated the adsorption was an exothermal reaction. Thus, low temperature was beneficial for the removal of Cr(VI). Optimal removal of Cr(VI) was achieved using the QPVA/0.5PDADMAC/0.1TEOSm membrane at a pH value of 2. Dynamic simulation was carried out simultaneously to determine if particle diffusion was the sole contributor for the adsorption rate, which was in accordance with the Langmuir isotherm adsorption model. Furthermore, the static adsorption amount (Q0) was 61.77 mg/g, and the efficiency of recycling the hybrid membranes was higher than 90%. Scanning electron microscopy (SEM) characterization showed the surface and the cross-section tightened after the Cr(VI) adsorption, thereby demonstrating the potential application of these hybrid membranes for Cr(VI) removal.

The adsorption of Sb(III) in aqueous solution by Fe2O3-modified carbon nanotubes

2013 ◽  
Vol 68 (3) ◽  
pp. 658-664 ◽  
Author(s):  
Tingchao Yu ◽  
Chao Zeng ◽  
Miaomiao Ye ◽  
Yu Shao
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Ph Value ◽  
Removal Rate ◽  
Nitrogen Adsorption ◽  
Solution Ph ◽  
Freundlich Adsorption Isotherm ◽  
Modified Carbon Nanotubes ◽  
Adsorption Desorption

A novel kind of iron oxide supported on carbon nanotubes (CNTs) was prepared for adsorption of antimony (Sb)(III) in aqueous solution. The iron (III) oxide (Fe2O3)-modified CNTs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption and Fourier transform infrared spectrometer. Parameters affecting the adsorption efficiencies, including solution pH value, initial Sb(III) concentration, adsorbent dosage, adsorption time and temperature, were investigated. The results indicate that the removal rate of Sb(III) by Fe2O3-modified CNTs is 99.97% under the initial Sb(III) concentration of 1.5 mg/L, adsorbents dosage of 0.5 g/L, temperature of 25 oC and pH value of 7.00, which is 29.81% higher than that of the raw CNTs. The adsorption capacity increased correspondingly from 3.01 to 6.23 mg/g. The equilibrium adsorption data can be fitted to the Freundlich adsorption isotherm. In addition, it has been found that the solution pH values and adsorption temperatures have no significant influence on Sb(III) removal.

scholarly journals Comparative study on the synthesis of magnetic ferrite adsorbent for the removal of Cd(II) from wastewater

2018 ◽  
Vol 36 (7-8) ◽  
pp. 1456-1469 ◽  
Author(s):  
Fang Liu ◽  
Kanggen Zhou ◽  
Quanzhou Chen ◽  
Aihe Wang ◽  
Wei Chen
Keyword(s):  
Aqueous Solution ◽  
Wastewater Treatment ◽  
Adsorption Capacity ◽  
Settling Velocity ◽  
Ph Value ◽  
Cost Effective ◽  
Precipitation Method ◽  
Maximum Adsorption Capacity ◽  
Effects Of Ph ◽  
Magnetic Ferrites

The magnetic ferrites were synthesized at ambient temperature through the precipitation method in aqueous solution at varying pH values and were used as novel adsorbents for heavy metal-containing wastewater treatment. The magnetic ferrites were applied for the removal of Cd(II) ion from wastewater. The synthesized magnetic ferrites were characterized by settling velocity, X-ray diffraction, scanning electron microscopy, laser particles size analyzer, and vibrating sample magnetometer. The effects of pH value and contact time on the adsorption process were investigated. The magnetic ferrites had a saturation magnetization value of 82.30 emu/g and a settling velocity of 2%, indicating easy separation from aqueous solution under magnetic field. The adsorption of Cd(II) onto the magnetic ferrites followed the pseudo-second-order kinetics and the Langmuir isotherm model. The most suitable pH condition for the synthesis of magnetic ferrite with optimal Cd(II) adsorption capacity was 9.0, and a maximum adsorption capacity of 160.91 mg/g for Cd(II) ions can be achieved. Based on the cost analysis, the magnetic ferrite was a cost-effective adsorbent for Cd-containing wastewater treatment.

Removal of Dichloroethylene in Water Using a Novel TCAS-Loaded Resin

2013 ◽  
Vol 634-638 ◽  
pp. 334-337
Author(s):  
Miao Miao He ◽  
Xiao Jun Hu ◽  
Yong Biao Peng ◽  
Xin He
Keyword(s):  
Aqueous Solution ◽  
Anion Exchange ◽  
Adsorption Mechanism ◽  
Exchange Resin ◽  
Ph Value ◽  
Anion Exchange Resin ◽  
Operating Temperature ◽  
Removal Rate ◽  
Static Tests ◽  
Loaded Resin

Through the method of the static tests, the removal rate of aqueous dichloroethylene onto a new TCAS-loaded resin was researched. This TCAS-loaded resin was made of a novel supramolecular acceptor compound named thiacalix[4]arenetetrasulfonate(TCAS) and anion exchange resin, and the adsorption mechanism was discussed preliminarily. The results of adsorption indicated that the pH value was an important factor for the removal of dichloroethylene and it would be better for the adsorption if the pH value was greater than 6. The operating temperature should be controlled in 5 to 15°C for the adsorption of dichloroethylene onto TCAS-loaded resin while the removal rate decreased with the temperature increasing and the best time for reaction was 40min. The removal rate of dichloroethylene in aqueous solution was better when 25mL aqueous solution of dichloroethylene (1.0mg/L) was adsorbed by 0.5g TCAS-loaded resin. The dichloroethylene can be resolving and TCAS-loaded resin can be reused.

Sign in / Sign up

Export Citation Format

Share Document