scholarly journals Metal extraction from Cetraria islandica (L.) Ach. lichen using low pH solutions

2008 ◽  
Vol 73 (4) ◽  
pp. 405-413 ◽  
Author(s):  
Ana Cuculovic ◽  
Mirjana Pavlovic ◽  
Dragan Veselinovic ◽  
Scepan Miljanic
Keyword(s):  
Complex Formation ◽  
Acid Rain ◽  
Metal Ion ◽  
Metal Content ◽  
Ph Value ◽  
Low Ph ◽  
Metal Extraction ◽  
Ph Values ◽  
All Solutions ◽  
Extraction Of Metals

Extraction of metals (K, Al, Ca, Mg, Fe, Cu, Ba, Zn, Mn and Sr) from dry Cetraria islandica (L.) Ach. lichen was performed using solutions similar to acid rain (solution A H2SO4-HNO3-(NH4)2SO4 and solution B H2SO4- -HNO3-(NH4)2SO4-NH4NO3). The pH values of these solutions were 2.00, 2.58, 2.87, 3.28, and 3.75. Five consecutive extractions were performed with each solution. In all solutions, the extracted metal content, except Cu and Ca, was the highest in the first extract. The highest percentage of the metals desorbed in the first extraction was obtained using solutions with low pH values, 2.00, 2.58, and 2.87. The lowest percentage in the first extraction was obtained using solutions with pH 3.28 and pH 3.75, indicating influence of the H+ ion on the extraction. According to the results obtained, the investigated metals form two groups. The first group includes K, Al, Ca, Mg, and Fe. They were extracted in each of the five extractions at each of the pH values. The second group includes Ba, Zn, Mn, Cu, and Sr, which were not all extracted at each pH value. The first group yielded three types of extraction curves when the logarithms of extracted metal amounts were plotted as a function of the number of successive extractions. These effects indicate that three different positions (centers) of metal ion accumulation exist in the lichen (due to sorption, complex formation, or other processes present in the tissues).

scholarly journals Mechanism of Coagulation of Humic Acid in Presence of Metal Ion Coagulants at Low pH Values

1970 ◽  
Vol 73 (5) ◽  
pp. 874-878 ◽  
Author(s):  
Takao YOTSUYANAGI ◽  
Katsumi GOTO ◽  
Masaichi NAGAYAMA
Keyword(s):  
Humic Acid ◽  
Metal Ion ◽  
Low Ph ◽  
Ph Values

scholarly journals Desorption of metals from Cetraria islandica (L.) Ach. Lichen using solutions simulating acid rain

2014 ◽  
Vol 66 (1) ◽  
pp. 273-284 ◽  
Author(s):  
Ana Cuculovic ◽  
Mirjana Pavlovic ◽  
Jelena Savovic ◽  
D.S. Veselinovic
Keyword(s):  
Detection Limit ◽  
Acid Rain ◽  
Metal Content ◽  
Strong Link ◽  
Ph Values ◽  
Metal Detection ◽  
Logarithmic Dependence ◽  
Solution Volume

Desorption of metals K, Al, Ca, Mg, Fe, Ba, Zn, Mn, Cu and Sr from Cetraria islandica (L.) with solutions whose composition was similar to that of acid rain, was investigated. Desorption of metals from the lichen was performed by five successive desorption processes. Solution mixtures containing H2SO4, HNO3 and H2SO4-HNO3 were used for desorption. Each solution had three different pH values: 4.61, 5.15 and 5.75, so that the desorptions were performed with nine different solutions successively five times, always using the same solution volume. The investigated metals can be divided into two groups. One group was comprised of K, Ca and Mg, which were desorbed in each of the five desorption processes at all pH values used. The second group included Al, Fe, Zn, Ba, Mn and Sr; these were not desorbed in each individual desorption and not at all pH values, whereas Cu was not desorbed at all under any circumstances. Using the logarithmic dependence of the metal content as a function of the desorption number, it was found that potassium builds two types of links and is connected with weaker links in lichen. Potassium is completely desorbed, 80% in the first desorption, and then gradually in the following desorptions. Other metals are linked with one weaker link (desorption 1-38%) and with one very strong link (desorption below the metal detection limit).

scholarly journals Column Extraction and Separation of Some Metal Ions by Diethylenetriamine Polysiloxane Immobilized Ligand System

2008 ◽  
Vol 5 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Nizam M. El-Ashgar
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Ph Value ◽  
Good Separation ◽  
Extraction And Separation ◽  
Ph Values ◽  
Ligand System ◽  
Chromatographic Parameters ◽  
Column Extraction ◽  
Optimum Separation

An extraction chromatographic solid porous polysiloxane functionalized by chelating diethylenetriamine ligand of the general formula P-(CH2)3-NH(CH2)2NH(CH2)2NH2, (Where P represents [Si-O]nsiloxane network) has been evaluated for the separation of Co(II), Ni(II) and Cu(II) from aqueous solutions. The chromatographic parameters of the separation method have been optimized. The ligand system retained Co(II), Cu(II) and Zn(II) effectively when used as a metal ion extractant by controlling the pH value. The ligand system also shows a good separation of a mixture of metal ions Co(II), Ni(II) and Cu(II) when used as chromatographic stationary phase. The optimum separation pH values were 4.5, 4 for Co(II) and Ni(II) respectively, while a solution of 0.1 M HNO3was used to elute Cu(II). Metal ions were also preconcentrated at pH 5.5. The chemisorbed metal ions were regenerated from the solid extractant using 0.5 M HCl.

scholarly journals Influence of pH and ionic strength on the aggregation behaviors of xylan rich hemicelluloses with alkaline lignins

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7608-7622
Author(s):  
Guichun Hu ◽  
Jinguang Hu ◽  
Honglei Chen ◽  
Shunxi Song ◽  
Fuqiang Chu
Keyword(s):  
Particle Size ◽  
Self Assembly ◽  
Main Chain ◽  
Ph Value ◽  
Low Ph ◽  
Ph Values ◽  
Wide Range ◽  
Nacl Concentration ◽  
Aggregation Behaviors ◽  
Influence Of Ph

The evolution of xylan-rich hemicelluloses (XH) aggregation behaviors in the presence of alkaline lignins (AL) under a wide range of pH values and NaCl concentration were investigated via dynamic light scattering and turbidity measurements. XH isolated from wheat straw contain a xylose backbone with arabinose side chains and a small amount of phenol groups. XH tend to aggregate in solution due to their low ratio of arabinose to xylose and hydrophobic phenol groups. AL interact with XH through the phenol groups bonded to the hemicellulose main chain to form an AL-XH complex. As the pH value decreases, the particle size and turbidity of AL, XH and their bonded complex all increase. The size of the AL-XH complex agglomerate is greater than the size of a XH at the same pH value, which indicates that the self-assembly of lignin molecules initiate the aggregation of XH. The particle size and turbidity of XH and AL-XH complexes increase as the XH concentration increase. At low pH values, e.g., 6.0, the particle size of the AL-XH complex more obviously increases compared to the XH particles. The size and turbidity of the AL, XH, and AL-XH complex agglomerates increased as the NaCl concentration increased.

scholarly journals Mechanical Behavior and Constitutive Model for Loess Samples under Simulated Acid Rain Conditions

2021 ◽  
Author(s):  
xia ye ◽  
Enlong Liu ◽  
Baofeng Di ◽  
yayang yu
Keyword(s):  
Mechanical Properties ◽  
Acid Rain ◽  
Mechanical Model ◽  
Ph Value ◽  
Simulated Acid Rain ◽  
Test Results ◽  
Hardening Model ◽  
Ph Values ◽  
Scanning Electron ◽  
Peak Value

Abstract In this paper, the sulfuric acid solution is diluted to pH 5.0, 4.0 and 3.0 to simulate the acid rain condition, and the triaxial compressional tests and scanning electron microscope are carried out to study the mechanical properties and evolution of the microstructure of the saturated loess samples. The results demonstrate that acid rain increases the porosity of loess samples, and the pore distribution is not uniform, so that the mechanical properties of loess samples change. With the decrease of pH value, the peak value of the deviatoric stress and the volumetric contraction of loess samples decreases, which causes the strength of soil to decrease. Furthermore, the framework of the chemical-mechanical model for loess under the action of acid rain is established, in which the loess is considered as porous medium material, and the variable of acid rain at different pH values through the degree of chemical reaction is taken into account in the double-hardening model, and the model is also verified by the triaxial test results finally.

Study of Electrochemical Behavior of the Transmission Tower Galvanized Layer in Simulated Acid Rain Solution

2013 ◽  
Vol 361-363 ◽  
pp. 1042-1045
Author(s):  
Hua Ling Deng ◽  
Qi Lei Sun
Keyword(s):  
Acid Rain ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Low Ph ◽  
Simulated Acid Rain ◽  
Corrosion Products ◽  
Precipitation Process ◽  
Layer Surface ◽  
Transmission Tower

Using electrochemical impedance spectroscopy (EIS), polarization curve and X-ray diffraction technique, electrochemical behavior of the transmission tower material Q460 galvanized layer was studied in simulated acid rain solution. The results show that: galvanized layers take place local corrosion in simulated acid rain solution, the corrosion products will fill the hole, and cover on galvanized layer surface, the generated white corrosion products mainly ZnSO4 ·H2O.The current generate in the process of corrosion, galvanized layer surface take place electrochemical corrosion. Galvanized layer solution at pH 2.4 and 3.8 of the simulated acid rain in the corrosion process is controlled by the charge transfer process, with the decrease of solution pH value, the corrosion rate increases. Zinc are more sensitive to H+ in the solution, in low pH value of solution, due to the strong hydrogen precipitation process, the zinc surface adsorption of hydrogen bubble around, its dissolution rate is higher than the surface of the other part of the zinc, namely in low pH value of acid rain solution, H+ by depolarization process not only directly accelerate the corrosion of zinc, can through the strong hydrogen evolution process at the same time accelerate the dissolution of zinc.

The sorption of lead and cadmium species by clay minerals

1977 ◽  
Vol 30 (7) ◽  
pp. 1417 ◽  
Author(s):  
H Farrah ◽  
WF Pickering
Keyword(s):  
Metal Ion ◽  
Ph Value ◽  
Cadmium Ions ◽  
Ph Values ◽  
Metal Ion Adsorption ◽  
Lead And Cadmium ◽  
Anionic Complexes ◽  
The Stability ◽  
Protonated Ligand ◽  
Ligand Species

The effect of pH changes and the presence of ligands on the uptake of lead and cadmium ions by three types of clay mineral (kaolinite, illite and montmorillonite) has been investigated. ��� In the absence of ligands, metal ion adsorption increases gradually with increasing pH until a threshold pH value is exceeded, whereupon total precipitation/sorption (attributed to formation of hydroxy species) occurs. With ligands present, the threshold point tends to shift to higher pH values, the magnitude of the effect depending on the stability of the metal complex formed. Adsorption of cationic metal complexes is subject to competition from charged protonated ligand species; anionic complexes are not sorbed.

scholarly journals Original Research. Evaluation of Dental Erosion in a Group of Romanian Children Diagnosed with Gastroesophageal Reflux Disease

2017 ◽  
Vol 2 (s1) ◽  
pp. 17-20
Author(s):  
Krisztina Mártha ◽  
Alexandru Ogodescu ◽  
Daniela Eșian ◽  
Cristina Bica ◽  
Eugen Bud
Keyword(s):  
Gastroesophageal Reflux Disease ◽  
Gastroesophageal Reflux ◽  
Reflux Disease ◽  
Ph Value ◽  
Statistical Significance ◽  
Dental Erosion ◽  
Low Ph ◽  
Original Research ◽  
Ph Values ◽  
Dmft Index

AbstractGastroesophageal reflux disease (GERD) is a very common digestive disorder, which occurs when the acidic contents of the stomach returns into the esophagus to some extent, reaching the mouth, thereby increasing the frequency of dental erosion and caries. Since saliva plays a huge role in oral homeostasis, it is important to examine the role of this parameter in the appearance of the above mentioned oral lesions. The aim of our study was evaluate the oral condition of children suffering from reflux disease and to assess the relationship between salivary pH and the incidence of dental erosion and caries. In this prospective study we examined 25 children diagnosed with GERD, referred for hospitalization. Bedside intra-oral examination (DMFT index, gingival index) and strip method pH value determination was performed. We observed that patients with low pH values had increased caries frequency, and dental erosion was also noticeable. Statistical significance was determined comparing the DMFT index in groups with different pH values. We concluded that the high number of erosions is closely related to gastroesophageal reflux disease, as a consequence of the low pH value, which represents the main cause of oral manifestations in GERD.

Study on the Effect of Amphoteric Bagasse Hemicellulose on Heavy Metal Adsorption

2011 ◽  
Vol 399-401 ◽  
pp. 1282-1288 ◽  
Author(s):  
Li Jun Wang ◽  
Xin Liang Liu ◽  
Meng Ling Weng ◽  
Shuang Xi Li ◽  
Fu Sheng Wu ◽  
...  
Keyword(s):  
Linear Model ◽  
Metal Ion ◽  
Ph Value ◽  
Absorption Capacity ◽  
Heavy Metal Adsorption ◽  
Adsorption Dynamics ◽  
Adsorption Time ◽  
Initial Concentration ◽  
Ph Values ◽  
Pseudo Second Order

In this paper, ions i.e. Cu2+, Pb2+and Cd2+ were absorbed by the amphoteric bagasse hemicelluloses, and the influences of pH value, adsorption time and the initial concentration of metal ion have been studied. The results show that the optimal adsorption pH values for Cu2+, Pb2+ and Cd2+ are 6.5, 6.0 and 7.5, respectively. The adsorption capacity to ions Cu2+, Pb2+ and Cd2+ reaches the maximum values when the adsorption time is 180 min. Net adsorption to ions Cu2+, Pb2+ and Cd2+ increases with increasing the initial concentration of the metal ions. Analysis results of adsorption dynamics show that the adsorption of Cu2+, Pb2+ and Cd2+ follows Ho 's Pseudo second-order kinetics linear model. It can be seen from the adsorption isothermal research that absorption of the amphoteric bagasse hemicelluloses to ions Cu2+, Pb2+and Cd2+ can be well described by the Langmuir isotherm linear model. Moreover, the theoretical values of the maximum absorption capacity qmax for ions Cu2+, Pb2+ and Cd2+ were determined to be 21.98 mg/g, 81.97 mg/g and 31.85 mg/g, respectively.

Evaluation of the Influence of Acid Rain on the Property of Plant Mediums by Simulation

2011 ◽  
Vol 236-238 ◽  
pp. 2997-3000
Author(s):  
Jia Horng Lin ◽  
Jin Mao Chen ◽  
Ching Wen Lin ◽  
Wen Hao Hsing ◽  
Chen Fang Tsai ◽  
...  
Keyword(s):  
Acid Rain ◽  
Ph Value ◽  
Cotton Fibers ◽  
Ph Values ◽  
Weight Losses ◽  
Suitable Environment

Acid rain has drawn much attention recently. This study was about evaluating the acid-rain-resistant and eco wall which was made of cotton fibers and Tencel fibers. In the experiment, two types of fibers were immersed in stimulated-acid-rain solutions for a week and weighted respectively after drying. This same procedure was repeated weekly three times; meanwhile, the fibers’ pH values were measured daily. The result showed that cotton fibers surpassed Tencel fibers, demonstrating smaller weight losses and positive pH results. The cotton fibers were able to adjust its pH value to 6.8, which provided a suitable environment for plants.

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