Removal of As, Cr and Cd by Absorptive Filtration

2013 ◽  
Vol 6 (1) ◽  
pp. 73-80 ◽  
Keyword(s):  
Environmental Protection Agency ◽  
Batch Adsorption ◽  
Solution Ph ◽  
Sand Filters ◽  
Bench Scale ◽  
Sand Surface ◽  
Iron Solution ◽  
The Us ◽  
Naoh Solution ◽  
In Series

The US Environmental Protection Agency (USEPA) recently introduced more stringent arsenic regulations by lowering the maximum contaminant level (MCL) to 10 ìg l-1 (ppb) arsenic in drinking water. During the present study, an iron solution injection sand filtration process was designed and tested to selectively remove arsenic (As(V)), chromate (Cr(VI)) and cadmium (Cd(II)) from aqueous solutions down to trace level. Bench scale sand columns with a chemical feeding system were used to conduct the filtration study. The filtration results demonstrate that As(V) could be removed by ferric solution-treated sand filters from 2,000 ìg l-1 (ppb) down to less than 5 ìg l-1 (ppb) using two sand filters connected in series (two stage filtration). During the filtration, ferric concentrations in the first and second filters were maintained at 5 and 2 ppm, respectively, through a continuous injection scheme. Bench scale filtration results suggest that Cr(VI) could also be effectively removed by injection of ferrous solution into the sand columns. Similar ferric treatment of the sand columns also significantly increased Cd(II) removal. Batch adsorption experimental results suggest that when solution pH is lower than 8, arsenate can be removed by iron-treated sand. Arsenate-saturated sand can be regenerated using a high pH (pH > 12) solution. Scanning Electron Microscope (SEM) and energy dispersive x-ray (EDX) studies suggest that very little amount of Fe on the sand surface was dissolved when the sand was regenerated using a dilute NaOH solution (pH = 13).

scholarly journals Evaluation of Alternative Annular Denuder Systems for the Collection of Fine Aerosol Particulate Matter

2020 ◽  
Vol 2 (1) ◽  
pp. 96-110
Author(s):  
Spencer ◽  
Osborne ◽  
Van Heyst
Keyword(s):  
Particulate Matter ◽  
Environmental Protection Agency ◽  
Particle Deposition ◽  
Inorganic Aerosols ◽  
Filter Pack ◽  
Fine Aerosol ◽  
The Us ◽  
In Series ◽  
Us Epa ◽  
Annular Denuder

Due to the complex manner in which secondary inorganic aerosols (SIAs) form, a need exists to develop a methodology to measure PM2.5 emissions from agricultural operations to better understand the contribution of SIAs to the PM2.5 fraction. When sampling particulate matter (PM), annular denuder systems (ADS) are a United States Environmental Protection Agency (US EPA) approved system used to measure both gaseous and particulate components of aerosols. While collecting basic gases, such as ammonia, using nine denuders was feasibly demonstrated in poultry housing units but the ability of additional denuders to accurately collect the SIAs on the filters is yet to be demonstrated. An experiment was designed to assess particle deposition behaviors throughout three different ADS configurations. It was determined that the nine denuder configuration resulted in particles being impacted and retained, mainly in the U-bend junctions, prior to reaching the filters with only 87.2% of PM2.5 reaching the filter pack. The US EPA-prescribed ADS configuration had 99.4% of PM2.5 reaching the filters, indicating that there is an impact due to the U-Bend addition to the system. It was further demonstrated that having additional denuders in series with no U-Bend had no significant impact on PM2.5 deposition on the filters with 98.9% of PM2.5 being collected.

scholarly journals The production of valuable products and fuel from plastic waste in Africa

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
M. Opoku Amankwa ◽  
E. Kweinor Tetteh ◽  
G. Thabang Mohale ◽  
G. Dagba ◽  
P. Opoku
Keyword(s):  
Environmental Protection Agency ◽  
Road Construction ◽  
Plastic Waste ◽  
Liquid Fuels ◽  
Environmental Costs ◽  
Waste Generation ◽  
Sustainable Environment ◽  
Trade Offs ◽  
The Us ◽  
Shipping Containers

AbstractGlobal plastic waste generation is about 300 million metric tons annually and poses crucial health and environmental problems. Africa is the second most polluted continent in the world, with over 500 shipping containers of waste being imported every month. The US Environmental Protection Agency (EPA) report suggests that about 75% of this plastic waste ends up in landfills. However, landfills management is associated with high environmental costs and loss of energy. In addition, landfill leachates end up in water bodies, are very detrimental to human health, and poison marine ecosystems. Therefore, it is imperative to explore eco-friendly techniques to transform plastic waste into valuable products in a sustainable environment. The trade-offs of using plastic waste for road construction and as a component in cementitious composites are discussed. The challenges and benefits of producing liquid fuels from plastic waste are also addressed. The recycling of plastic waste to liquid end-products was found to be a sustainable way of helping the environment with beneficial economic impact.

Poly Silk Peptide Film PH Sensor Based on Zero Current Potentiometry

2012 ◽  
Vol 450-451 ◽  
pp. 554-556
Author(s):  
Ming Ming Ma ◽  
Zhi Tong ◽  
Yong Wen
Keyword(s):  
Graphite Electrode ◽  
Ph Sensor ◽  
Reference Electrode ◽  
Pencil Graphite Electrode ◽  
Solution Ph ◽  
Counter Electrodes ◽  
System A ◽  
Zero Current ◽  
In Series ◽  
Silk Peptide

A poly silk peptide film pH sensor has been developed using zero current potentiometry system. A poly silk peptide film coated pencil graphite electrode is connected in series between the working and counter electrodes of a potentiostat, and immersed in solution together with a reference electrode. When the solution pH varies, the resulting zero current potentiometry is linear with the values of the solution pH in the range of 1.81 to 11.58. This pH sensor shows high stability, accuracy, selectivity and reproduction.

scholarly journals Adsorption of Pollutants from Aqueous Solutions Using Activated and Non-Activated Oak Shells: Parametric and Fractional Factorial Design Study. Part II. Removal of Phenol and Dyes

2003 ◽  
Vol 21 (2) ◽  
pp. 189-198
Author(s):  
Sameer Al-Asheh ◽  
Fawzi Banat ◽  
Rana Saeidi ◽  
Salam Abu Zaid
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Factorial Design ◽  
Fractional Factorial Design ◽  
Sorption Process ◽  
Fractional Factorial ◽  
Phenol Concentration ◽  
Blue Dye ◽  
Batch Adsorption ◽  
Solution Ph

As in Part I, non-activated (natural) and chemically activated oak shells were evaluated for their ability to remove phenol and Methylene Blue (as a typical dye component) from aqueous solutions. Batch adsorption experiments were conducted to investigate the effect of contact time, sorbent concentration, phenol concentration and the pH of the solution on the sorption process. Activated oak shells adsorbed more phenol than natural oak shells under the same conditions. A decrease in sorbent concentration or an increase in phenol concentration or solution pH resulted in an increase in phenol uptake by the oak shells. The uptake of Methylene Blue increased with decreasing sorbent concentration and with an increase in the dye concentration, but decreased significantly with solution pH. According to the fractional factorial design technique, the sorbent type employed (natural or activated) had the most significant influence on phenol or Methylene Blue uptake followed by sorbent concentration and then sorbate concentration. Interaction amongst the different operating variables played an important role in the uptake of phenol or Methylene Blue dye by the adsorbent considered.

Effect of pH on chloride absorption in the flounder intestine

1988 ◽  
Vol 255 (2) ◽  
pp. G247-G252 ◽  
Author(s):  
A. N. Charney ◽  
J. I. Scheide ◽  
P. M. Ingrassia ◽  
J. A. Zadunaisky
Keyword(s):  
Small Intestine ◽  
Short Circuit ◽  
Ph Effect ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Solution Ph ◽  
Transport Pathway ◽  
Ussing Chambers ◽  
Chloride Absorption ◽  
In Series

Chloride absorption in the small intestine of the winter flounder, Pseudopleuronectes americanus, is reported to be sensitive to ambient pH. We studied this sensitivity in isolated stripped intestinal mucosa mounted in modified Ussing chambers. Unidirectional 36Cl fluxes (JClm----s, JCls----m) were measured under short-circuited conditions in bathing solutions containing various combinations of HCO3- (0-20 mM), partial pressure of CO2 (0-36 mmHg), and pH (6.77-7.85). We found that JClm----s, net 36Cl flux (JClnet), and short-circuit current (Isc) increased and JCls----m decreased predominately in response to increases in bathing solution pH. There was a linear relationship between pH and both JClnet (r = 0.92, P less than 0.01) and Isc (r = 0.96, P less than 0.005) between pH 6.77 and 7.74. The pH effect was completely reversible, did not require either CO2 or HCO3-, and was not affected by the presence of mucosal barium at 1 mM. Mucosal bumetanide (0.1 mM) completely inhibited the pH effect. These data suggest that the process by which Cl- is absorbed in the flounder intestine is sensitive to pH. The data do not indicate whether pH affects Na+-K+-2Cl- cotransport or a Cl- transport pathway in series with this process. The direction of Cl- absorption in response to pH contrasts with inverse relation of pH and Cl- absorption in mammalian small intestine.

scholarly journals Polymer Composite—A Potential Biomaterial for the Removal of Reactive Dye

2012 ◽  
Vol 9 (4) ◽  
pp. 1823-1834 ◽  
Author(s):  
P. N. Palanisamy ◽  
A. Agalya ◽  
P. Sivakumar
Keyword(s):  
Ion Exchange ◽  
Langmuir Isotherm ◽  
Isosteric Heat ◽  
Reactive Dye ◽  
Isotherm Model ◽  
Batch Adsorption ◽  
Solution Ph ◽  
Saw Dust ◽  
Exchange Adsorption ◽  
Langmuir Isotherm Model

Poly Pyrrle saw dust composite was prepared by reinforcement of natural wood saw dust (obtained fromEuphorbia Tirucalli Lwood) and Poly Pyrrole matrix phase. The present study investigates the adsorption behaviour of Poly Pyrrole Saw dust Composite towards reactive dye. The batch adsorption studies were carried out by varying solution pH, initial dye concentration, contact time and temperature. The kinetic study showed that adsorption of Reactive Red by PPC was best represented by pseudo-second order kinetics with ion exchange adsorption. The equilibrium data were analyzed by Freundlich and Langmuir isotherm model. The equilibrium isotherm data were fitted well with Langmuir isotherm model. The maximum monolayer adsorption capacities calculated by Langmuir model were 204.08 mg/g for Reactive Red at 303 K. The thermodynamic parameters suggest the spontaneous, endothermic nature of ion exchange adsorption with weak Vader walls force of attraction. Activation energy for the adsorption of Reactive by Poly Pyrrole Composite was 11.6387 kJ/mole, Isosteric Heat of adsorption was 48.5454 kJ/mole also supported the ion exchange adsorption process in which forces of attraction between dye molecules and PPC is weak.

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

scholarly journals PM2.5 and Ozone Air Pollution Levels Have Not Dropped Consistently Across the US Following Societal Covid Response

2020 ◽  
Author(s):  
Bujin Bekbulat ◽  
Joshua S. Apte ◽  
Dylan B Millet ◽  
Allen Robinson ◽  
Kelley C. Wells ◽  
...  
Keyword(s):  
Air Pollution ◽  
Environmental Protection Agency ◽  
Fine Particulate Matter ◽  
Pollution Levels ◽  
Secondary Pollutants ◽  
The Us ◽  
Many Sources ◽  
Primary Pollutant ◽  
Ozone Levels ◽  
At Home

<p>Analysis of a large national dataset of fine particulate matter (PM2.5) and ozone air pollution from the US Environmental Protection Agency indicate opposing differences in average concentrations during the covid response period, relative to expected levels. These are the two most important pollutants in terms of public health impacts and regulatory non-attainment in the US. Post-covid response, average PM2.5 levels are slightly higher (~5%) than expected; average ozone levels are slightly lower (~5%). The size of post-response ozone anomaly has decreased with time and by week 6 after the first stay-at-home order was enacted (April 29- May 5, 2020), ozone levels were higher than expected. In addition, no individual US state had lower-than-expected PM2.5 and ozone for all weeks post- covid response. Two non-covid factors, meteorology and regional transport, do not fully explain observed trends. These findings are unexpected given the large reduction in many household’s activities associated with “stay at home” and other covid responses. We hypothesize that this result partly arises from the fact that ozone and the majority of PM2.5 are secondary pollutants formed in the atmosphere from emissions from many sources (i.e., not just traffic). Preliminary analysis of nitrogen dioxide (NO2) data in a few cities reveals substantially lower-than-expected (~30%) concentrations post-covid. NO2 is a primary pollutant and is much more strongly associated with traffic than PM2.5 or ozone. </p><p><br></p>

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