Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects

2002 ◽  
Vol 1 (6) ◽  
pp. 421-426 ◽  
Author(s):  
Andrés H. Thomas ◽  
Carolina Lorente ◽  
Alberto L. Capparelli ◽  
Megh Raj Pokhrel ◽  
André M. Braun ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Folic Acid ◽  
Ph Effects ◽  
Solution Ph

Heterogeneous Fenton Catalytic Removal of Organic Pollutant in Aqueous Solution by using Coal Gangue as a Catalyst

2019 ◽  
Vol 12 (4) ◽  
pp. 312-325
Author(s):  
Jiwei Zhang ◽  
Jingjing Xu ◽  
Shuaixia Liu ◽  
Baoxiang Gu ◽  
Feng Chen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Removal Rate ◽  
Organic Pollutant ◽  
Coal Gangue ◽  
Ion Leakage ◽  
Heterogeneous Fenton ◽  
Solution Ph ◽  
X Ray

Background: Coal gangue was used as a catalyst in heterogeneous Fenton process for the degradation of azo dye and phenol. The influencing factors, such as solution pH gangue concentration and hydrogen peroxide dosage were investigated, and the reaction mechanism between coal gangue and hydrogen peroxide was also discussed. Methods: Experimental results showed that coal gangue has the ability to activate hydrogen peroxide to degrade environmental pollutants in aqueous solution. Under optimal conditions, after 60 minutes of treatment, more than 90.57% of reactive red dye was removed, and the removal efficiency of Chemical Oxygen Demand (COD) up to 72.83%. Results: Both hydroxyl radical and superoxide radical anion participated in the degradation of organic pollutant but hydroxyl radical predominated. Stability tests for coal gangue were also carried out via the continuous degradation experiment and ion leakage analysis. After five times continuous degradation, dye removal rate decreased slightly and the leached Fe was still at very low level (2.24-3.02 mg L-1). The results of Scanning Electron Microscope (SEM), energy dispersive X-Ray Spectrometer (EDS) and X-Ray Powder Diffraction (XRD) indicated that coal gangue catalyst is stable after five times continuous reuse. Conclusion: The progress in this research suggested that coal gangue is a potential nature catalyst for the efficient degradation of organic pollutant in water and wastewater via the Fenton reaction.

scholarly journals Crystal structure of the new hybrid material bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate

2015 ◽  
Vol 71 (11) ◽  
pp. 1384-1387
Author(s):  
Marwen Chouri ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Molar Ratio ◽  
Water Molecules ◽  
Site Symmetry ◽  
Two Dimensional ◽  
Slow Evaporation ◽  
Solution Ph

The title compound bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH = 1) containing bismuth(III) nitrate and 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10]4−bioctahedra (site symmetry -1) separated by layers of organic 1,4-diazoniabicyclo[2.2.2]octane dications [(DABCOH2)2+] and water molecules. O—H...Cl, N—H...O and N—H...Cl hydrogen bonds lead to additional cohesion of the structure.

Removal of Cr(VI) from Aqueous Solution by Acid Treated Fungal Biomass

2011 ◽  
Vol 197-198 ◽  
pp. 131-135
Author(s):  
Li Fang Zhang ◽  
Ying Ying Chen ◽  
Wen Jie Zhang
Keyword(s):  
Aqueous Solution ◽  
Fungal Biomass ◽  
Adsorption Model ◽  
Solution Ph ◽  
Initial Concentration ◽  
Biosorption Capacity ◽  
Penicillium Sp ◽  
Chromium Vi ◽  
Equilibrium Data ◽  
Biosorption Equilibrium

Biosorption of chromium (VI) ions from aqueous solution with fungal biomass Penicillium sp. was investigated in the batch system. The influence of contact time, solution pH, biosorbent concentration, initial concentration of Cr (VI) ions and temperature on biosorption capacity of Cr (VI) ions was studied. The uptake of Cr (VI) was highly pH dependent and the optimum pH for biosorption of Cr (VI) ions was found to be 2.0. Biosorption capacity of Cr (VI) ions decreased with increased biosorbent concentration and increased with increase in initial concentration of Cr (VI) ions. The experiment results also showed that high temperatures increased the biosorption capacity of Cr (VI) by fungal biomass. It was found that the biosorption equilibrium data were fitted very well to the kangmuir as well as to the Freundlich adsorption model. The maximum sorptive capacities obtained from the Langmuir equation at temperature of 20, 30 and 40°C were 25.91, 32.68 and 35.97 mg/g for Cr (VI) ions, respectively. The results of this study indicated that the fungal biomass of Penicillium sp. is a promising biosorbent for removal of chromium (VI) ions from the water.

scholarly journals Adsorption of Phenol from Aqueous Solution Using Activated Carbon prepared from Coconut Shell

2017 ◽  
Vol 29 (1) ◽  
pp. 9-13
Author(s):  
Masuma Sultana Ripa ◽  
Rafat Mahmood ◽  
Sabrina Khan ◽  
Easir A Khan
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Adsorption Isotherm ◽  
Iodine Number ◽  
Chemical Engineering ◽  
Coconut Shell ◽  
Physical Activation ◽  
Batch Adsorption ◽  
Adsorption Model ◽  
Solution Ph

Adsorption separation of phenol from aqueous solution using activated carbon was investigated in this work. The adsorbent was prepared from coconut shell and activated by physical activation method. The coconut shell was first carbonized at 800°C under nitrogen atmosphere and activated by CO2 at the same temperature for one hour. The prepared activated carbon was characterized by Scanning Electron Microscope (SEM) and BET Surface Analyzer and by the determination of iodine number as well as Boehm titration. The iodine number indicates the degree of relative activation of the adsorbent. The equilibrium adsorption isotherm phenol from aqueous solution was performed using liquid phase batch adsorption experiments. The effect of experimental parameters including solution pH, agitation time, particle size, temperature and initial concentration was investigated. The equilibrium data was analyzed using Langmuir and Freundlich adsorption model to describe the adsorption isotherm and estimate the adsorption isotherm parameters. The results indicate the potential use of the adsorbent for removal of phenol from the aqueous solution.Journal of Chemical Engineering, Vol. 29, No. 1, 2017: 9-13

Comparison of Coal Ash and Activated Carbon for Removal of Humic Acid from Aqueous Solution

2013 ◽  
Vol 864-867 ◽  
pp. 1509-1512
Author(s):  
Xue Mei Zhang ◽  
Yan Zhang ◽  
Di Fan
Keyword(s):  
Aqueous Solution ◽  
Humic Acid ◽  
Activated Carbons ◽  
Removal Rate ◽  
Coal Ash ◽  
Cost Effective ◽  
Solution Ph ◽  
Adsorption Behaviors ◽  
Calcium Loading ◽  
Working Solution

This paper presents the adsorption behaviors of humic acid (HA) on coal ashes and powdered activated carbons (PACs). A bituminous coal, with or without calcium-loading, was used as a feedstock for coal ash preparation. The working solution of HA with a concentration of 20 mg/L was used in all adsorption tests. The results showed that calcium-enriched coal ash (CECA) gave rise to the removal rate of HA as high as 84.05%, much higher than those of raw coal ash (RCA) and PACs. The impacts of solution pH and adsorbent dosage on HA adsorption capacity were also investigated. It was found that lower pH facilitated to the removal of HA from aqueous solution by means of CECA, and the optimal CECA dosage was about 1.0g/L at pH 7.00. The data obtained in this study suggested that calcium-enriched coal ash could be useful and cost-effective in the treatment of wastewaters containing HA-like organic macro-molecules.

Irradiation Stability of Folic Acid in Powder and Aqueous Solution

2011 ◽  
Vol 59 (4) ◽  
pp. 1244-1248 ◽  
Author(s):  
Michel M. Araújo ◽  
Eric Marchioni ◽  
Martine Bergaentzle ◽  
Minjie Zhao ◽  
Florent Kuntz ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Folic Acid

scholarly journals Electrochemical oxidation of sulfamethoxazole using Ti/SnO2-Sb/Co-PbO2 electrode through ANN-PSO

2019 ◽  
Vol 84 (7) ◽  
pp. 713-727 ◽  
Author(s):  
Jiteng Wan ◽  
Chunji Jin ◽  
Banghai Liu ◽  
Zonglian She ◽  
Mengchun Gao ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Electrochemical Oxidation ◽  
Removal Efficiency ◽  
Current Density ◽  
Ph Value ◽  
Ann Model ◽  
Solution Ph ◽  
Pbo2 Electrode ◽  
Artificial Neural Network Ann ◽  
Major Factors

Even in a trace amounts, the presence of antibiotics in aqueous solution is getting more and more attention. Accordingly, appropriate technologies are needed to efficiently remove these compounds from aqueous environments. In this study, we have examined the electrochemical oxidation (EO) of sulfamethoxazole (SMX) on a Co modified PbO2 electrode. The process of EO of SMX in aqueous solution followed the pseudo-first-order kinetics, and the removal efficiency of SMX reached the maximum value of 95.1 % within 60 min. The effects of major factors on SMX oxidation kinetics were studied in detail by single-factor experiments, namely current density (1?20 mA cm-2), solution pH value (2?10), initial concentration of SMX (10?500 mg L-1) and concentration of electrolytes (0.05?0.4 mol L-1). An artificial neural network (ANN) model was used to simulate this EO process. Based on the obtained model, particle swarm optimization (PSO) was used to optimize the operating parameters. The maximum removal efficiency of SMX was obtained at the optimized conditions (e.g., current density of 12.37 mA cm-2, initial pH value of 4.78, initial SMX concentration of 74.45 mg L-1, electrolyte concentration of 0.24 mol L-1 and electrolysis time of 51.49 min). The validation results indicated that this method can ideally be used to optimize the related parameters and predict the anticipated results with acceptable accuracy.

The Influence of Carboxy Methyl Cellulose (CMC) and Solution pH on Carbon Fiber Dispersion in White Cement Matrix

2014 ◽  
Vol 493 ◽  
pp. 661-665 ◽  
Author(s):  
Ari Yustisia Akbar ◽  
Yulinda Lestari ◽  
Gilang Ramadhan ◽  
Septian Adi Candra ◽  
Eni Sugiarti
Keyword(s):  
Aqueous Solution ◽  
Carbon Fiber ◽  
Methyl Cellulose ◽  
Cement Matrix ◽  
Solution Ph ◽  
Fiber Dispersion ◽  
Reinforced Composite ◽  
Disperse Carbon ◽  
Reinforced Cement ◽  
Matrix Morphology

Dispersion of carbon fiber in cement matrix is one of main challenges for fabricating carbon fiber reinforced cement based materials. In this study, the dispersion of carbon fiber was improved by pre-dispersion of carbon fiber in basic aqueous solution using different concentrations of CMC. The relationships of CMC concentration and pH solution toward carbon fiber dispersion in aqueous solution was evaluated by UVvis spectroscopy. In order to understand how carbon fiber is dispersed in cement matrix, morphology fiber carbon reinforced composite was examined. Experimental results show that aqueous solution of CMC is effective to disperse carbon fiber. In addition, dispersion of carbon fiber increases with increasing of pH of CMC solution.

Enrichment of amino acids from its aqueous solution by ultrasonic atomization and ultrafine bubbles

2021 ◽  
Author(s):  
Keiji Yasuda ◽  
Koji Hamada ◽  
Yoshiyuki Asakura
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Amino Acid ◽  
Enrichment Factor ◽  
Acid Concentration ◽  
Flow Rate ◽  
Amino Acid Concentration ◽  
Solution Ph ◽  
Ultrasonic Atomization ◽  
Enrichment Characteristics

Abstract The enrichment characteristics of amino acids by ultrasonic atomization were investigated. Samples were aqueous solutions of L-phenylalanine and L-tyrosine. The ratio of amino acid concentration in the mist to that in the solution was defined as the enrichment factor. As the flow rate of carrier gas became higher, the collection mass of mist increased and the enrichment factor decreased. The enrichment factor depended on the solution pH. The enrichment factor increased with decreasing amino acid concentration in the solution and enhanced by the addition of ultrafine bubbles.

scholarly journals Efficient Removal of Diclofenac from Aqueous Solution by Potassium Ferrate-Activated Porous Graphitic Biochar: Ambient Condition Influences and Adsorption Mechanism

2019 ◽  
Vol 17 (1) ◽  
pp. 291 ◽  
Author(s):  
Nguyen Thi Minh Tam ◽  
Yunguo Liu ◽  
Hassan Bashir ◽  
Zhihong Yin ◽  
Yuan He ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Diclofenac Sodium ◽  
Maximum Adsorption Capacity ◽  
Potassium Ferrate ◽  
Solution Ph ◽  
Modified Biochar ◽  
Prepared Material ◽  
Endothermic Process ◽  
One Step

Porous graphitic biochar was synthesized by one-step treatment biomass using potassium ferrate (K2FeO4) as activator for both carbonization and graphitization processes. The modified biochar (Fe@BC) was applied for the removal of diclofenac sodium (DCF) in an aqueous solution. The as-prepared material possesses a well-developed micro/mesoporous and graphitic structure, which can strengthen its adsorption capacity towards DCF. The experimental results indicated that the maximum adsorption capacity (qmax) of Fe@BC for DCF obtained from Langmuir isotherm simulation was 123.45 mg·L−1 and it was a remarkable value of DCF adsorption in comparison with that of other biomass-based adsorbents previously reported. Thermodynamic quality and effect of ionic strength studies demonstrated that the adsorption was a endothermic process, and higher environmental temperatures may be more favorable for the uptake of DCF onto Fe@BC surface; however, the presence of NaCl in the solution slightly obstructed DCF adsorption. Adsorption capacity was found to be decreased with the increase of solution pH. Additionally, the possible mechanism of the DCF adsorption process on Fe@BC may involve chemical adsorption with the presence of H-bonding and π–π interaction. With high adsorption capacity and reusability, Fe@BC was found to be a promising absorbent for DCF removal from water as well as for water purification applications.

Sign in / Sign up

Export Citation Format

Share Document