scholarly journals Effects of Silicic Acid on Leaching Behavior of Arsenic from Spent Calcium-Based Adsorbents with Arsenite

2021 ◽  
Vol 13 (23) ◽  
pp. 12937
Author(s):  
Hajime Sugita ◽  
Terumi Oguma ◽  
Junko Hara ◽  
Ming Zhang ◽  
Yoshishige Kawabe
Keyword(s):  
Silicic Acid ◽  
Environmental Stability ◽  
Contaminated Water ◽  
Leaching Behavior ◽  
Initial Concentration ◽  
Primary Mechanism ◽  
Calcium Silicates ◽  
To Come ◽  
Normalized Concentration

The spent adsorbents that remain after being used to purify As-contaminated water constitute waste containing a large amount of As. These spent adsorbents, after being disposed, are likely to come into contact with silicic acid leached from the soil or cementitious solidification materials. Thus, it is crucial the evaluate the effects of silicic acid on spent adsorbents. In this study, the effects of silicic acid on spent Ca-based (CaO and Ca(OH)2) adsorbents with arsenite were investigated. The As leaching ratio for the spent adsorbents decreased with an increase in the initial concentration of silicic acid in the liquid. Under the tested conditions, the As leaching ratio decreased from 8–9% to less than 0.7% in the presence of silicic acid at an initial Si-normalized concentration of 100 mg/L. The primary mechanism behind the inhibition of As leaching by silicic acid was determined to be re-immobilization via the incorporation of arsenite during the formation of calcium silicates. In the presence of silicic acid, spent Ca-based adsorbents with arsenite had a lower As leaching ratio than those with arsenate. Therefore, spent Ca-based adsorbents with arsenite were found to have a higher environmental stability than those with arsenate.

EFFECTS OF SILICIC ACID ON ENVIRONMENTAL STABILITY OF SPENT CALCIUM-BASED ARSENIC ADSORBENTS

2018 ◽  
Vol 74 (7) ◽  
pp. III_493-III_502
Author(s):  
Hajime SUGITA ◽  
Terumi OGUMA ◽  
Ming ZHANG ◽  
Junko HARA ◽  
Yoshishige KAWABE
Keyword(s):  
Silicic Acid ◽  
Environmental Stability

scholarly journals Development of a bioreactor system for the remediation of endosulphan

2018 ◽  
Vol 2 (1) ◽  
pp. 1-8 ◽  
Author(s):  
K. Jesitha ◽  
P. S. Harikumar
Keyword(s):  
Detection Limit ◽  
Calcium Alginate ◽  
Packed Bed ◽  
Alginate Beads ◽  
Soil Samples ◽  
Packed Bed Reactor ◽  
Contaminated Water ◽  
Initial Concentration ◽  
Bioreactor System ◽  
Ca Alginate

Abstract A bioreactor system that consisted of Pseudomonas fluorescens cells immobilised in calcium-alginate beads was utilised to remediate endosulphan contaminated water and soil. A packed bed reactor system was designed for the bio-degradation of endosulphan in artificially spiked water samples (initial concentration of endosulphan: 350 µg/L). Reactor studies with cell-immobilised Ca-alginate beads were conducted after checking their efficiency through batch and column degradation studies. The results showed that the concentration of toxic isomers of endosulphan (endosulphan alpha and endosulphan beta) was below the limit in the bioreactor during the 7th day of the experiment. Experiments conducted with contaminated soil samples (initial concentration of endosulphan: 1,000 μg/kg) indicated that the toxic isomers of endosulphan degraded to below the detection limit within 10 days and monitoring of endosulphan residues on the 14th day revealed that almost complete degradation of metabolites of endosulphan had occurred. The bioreactor system designed can be scaled up for remediation of endosulphan in contaminated areas.

scholarly journals Biosorption of Pb (II) and Zn (II) from aqueous solution by Oceanobacillus profundus isolated from an abandoned mine

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Wilson Mwandira ◽  
Kazunori Nakashima ◽  
Satoru Kawasaki ◽  
Allison Arabelo ◽  
Kawawa Banda ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Ion Concentration ◽  
Contaminated Site ◽  
Lead Ion ◽  
Contaminated Water ◽  
Metal Chelation ◽  
Anthropogenic Contamination ◽  
Initial Concentration ◽  
Growth Ph ◽  
Maximum Removal

AbstractThe present study investigated biosorption of Pb (II) and Zn (II) using a heavy metal tolerant bacterium Oceanobacillus profundus KBZ 3-2 isolated from a contaminated site. The effects of process parameters such as effect on bacterial growth, pH and initial lead ion concentration were studied. The results showed that the maximum removal percentage for Pb (II) was 97% at an initial concentration of 50 mg/L whereas maximum removal percentage for Zn (II) was at 54% at an initial concentration of 2 mg/L obtained at pH 6 and 30 °C. The isolated bacteria were found to sequester both Pb (II) and Zn (II) in the extracellular polymeric substance (EPS). The EPS facilitates ion exchange and metal chelation-complexation by virtue of the existence of ionizable functional groups such as carboxyl, sulfate, and phosphate present in the protein and polysaccharides. Therefore, the use of indigenous bacteria in the remediation of contaminated water is an eco-friendly way of solving anthropogenic contamination.

Purification of Contaminated Water with Chromium (VI) Using Pseudomonas aeruginosa

2016 ◽  
Vol 721 ◽  
pp. 143-148 ◽  
Author(s):  
Nora Noureddine ◽  
Samia Benhammadi ◽  
Fouad Kara ◽  
Hakim Aguedal ◽  
Abdelkader Iddou ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Hexavalent Chromium ◽  
Contact Time ◽  
Culture Broth ◽  
Contaminated Water ◽  
Toxic Heavy Metals ◽  
Initial Concentration ◽  
Chromium Vi ◽  
Batch System ◽  
Uncontaminated Soil

A bacterial strain Pseudomonas aeruginosa isolated from an uncontaminated soil has been used for the removal of hexavalent chromium (Cr (VI)). The experiments were carried out in batch system in a culture broth. The results obtained have shown that 100% of Cr (VI) are removed. Contact time, initial concentration of the hexavalent chromium, temperature, as well as the nature of the culture broth have influenced this elimination. To the initial concentration of 20g/L of Cr (VI) the elimination rates are lower, while the reverse occurs for an initial concentration of 8g/L. This study allows considering the use of Pseudomonas aeruginosa in the treatment of water polluted by toxic heavy metals such as Cr (VI).

A field study examining the relative importance of food and water as sources of cadmium for juvenile yellow perch (Perca flavescens)

2006 ◽  
Vol 63 (3) ◽  
pp. 549-557 ◽  
Author(s):  
Lisa D Kraemer ◽  
Peter GC Campbell ◽  
Landis Hare ◽  
Jean-Christian Auclair
Keyword(s):  
Yellow Perch ◽  
Perca Flavescens ◽  
Contaminated Water ◽  
Relative Importance ◽  
Heat Stable ◽  
Contaminated Food ◽  
To Come ◽  
Cd Exposure ◽  
Subcellular Level ◽  
All Treatment

To determine the relative importance of water and food as cadmium (Cd) sources for juvenile yellow perch (Perca flavescens, age 1+), fish were caged for up to 30 days in either a reference (Opasatica) or a Cd-contaminated (Dufault) lake and offered prey (zooplankton) from one of these lakes. We established four Cd-exposure regimes: a control, Cd-contaminated water only, Cd-contaminated food only, Cd-contaminated food and water. The 64 µm mesh cages used allowed the free exchange of water with the surrounding lake while retaining the added zooplankton prey for the perch. Cd in the gills and kidney of caged perch was taken up largely from lake water, whereas liver and gut Cd appeared to come from both dietary and aqueous sources. At the subcellular level (liver), the majority of the background Cd in control perch was associated with metal-sensitive fractions (organelles and heat-denatured proteins), whereas in perch exposed to waterborne or diet-borne Cd, the majority of the Cd was found in a metal-detoxified fraction (heat-stable proteins, metallothionein). For perch from all treatment levels, the higher the concentration of hepatic Cd, the greater the proportion of the Cd burden in this organ that was associated with the fraction containing metallothionein-like proteins.

Photocatalytic degradation of explosives contaminated water

2002 ◽  
Vol 46 (11-12) ◽  
pp. 139-145 ◽  
Author(s):  
S.-J. Lee ◽  
H.-S. Son ◽  
H.-K. Lee ◽  
K.-D. Zoh
Keyword(s):  
Photocatalytic Degradation ◽  
Total Nitrogen ◽  
Contaminated Water ◽  
Ammonium Ions ◽  
Nitrate Ion ◽  
Photocatalytic Reactor ◽  
Initial Concentration ◽  
Initial Ph ◽  
Alkaline Conditions ◽  
The Impact

This study was undertaken to examine the degradation of TNT, RDX and HMX in a circular photocatalytic reactor with TiO2 as a photocatalyst. We examined the impact of parameters such as the initial concentration, initial pH of solution on rates of photocatalized transformation, and the mineralization. The results showed that photocatalysis is an effective process for the degradation of TNT, RDX and HMX. They could be completely degraded in 150 min with 1.0 g/L TiO2 at pH 7. An increase in the photocatalytic degradation of HMX was noticed with decreasing initial HMX. The rates of RDX and HMX degradation were greater in neutral pH than in acidic and alkaline conditions. In case of TNT degradation, the rate of degradation was the fastest at pH 11. Approximately 82% TOC decrease in the TNT degradation was achieved after 150 min, whereas TOC decrease in RDX and HMX was 24% and 59%, respectively. Nitrate, nitrite, and ammonium ions were detected as the nitrogen byproducts from the photocatalysis, and more than 50% of the total nitrogen was recovered as nitrate ion in every explosives.

Impact of Relative Humidity on Modified Alkoxysilane Gels

2016 ◽  
Vol 714 ◽  
pp. 95-99
Author(s):  
Barbora Benetková ◽  
Adéla Peterová ◽  
Monika Slavíková ◽  
Petr Kotlík
Keyword(s):  
Relative Humidity ◽  
Silicic Acid ◽  
Building Materials ◽  
Objective Evaluation ◽  
Partial Solution ◽  
Huge Impact ◽  
To Come ◽  
Stone Consolidants ◽  
Different Levels ◽  
Acid Esters

Silicic acid esters have been used as stone consolidants for 50 years now. During this time they became the most popular consolidants for building materials, mainly thanks to their good properties during application. Despise all these positives, the use of alkoxysilanes brings also some drawbacks. The gel of the silicic acid esters, which is responsible for the consolidation, cracks and decays during several years after the treatment so that the consolidation has to be repeated. To suppress the cracking, the alkoxysilanes are often modified. In recent studies, we focused on modification of silicic acid ester gels by SiO2 and Al2O3 nanoparticles. Some of the prepared mixtures cracked less than the unmodified mixture under ambient condition. This work builds on these experiments and works with the selected modified mixtures. As the consolidants are widely used outdoors, it was necessary to compare the degree of cracking of modified gels under various conditions. In this experiment we focused on their cracking under different levels of relative humidity. As the objective evaluation of cracking was needed, we believe to come up with partial solution to this problem – to assort the extent of cracking to some defined category. The categories were defined according to our former experiences with observation of cracking states of the gels. We found out, that the change of relative humidity has huge impact on the way and extent to which the gels cracked. Knowing this information we may be able to prepare the modified consolidant, that better withstands outdoor conditions and thus to preserve our cultural heritage for longer time.

The Adsorption of Heavy Metal from Aqueous Solutions onto the Porous Biomorphic-Genetic Composite of Hydroxyapatite/Carbon with Eucalyptus and Bamboo Template

2015 ◽  
Vol 730 ◽  
pp. 260-264 ◽  
Author(s):  
Shuang Cao ◽  
Bin Huang ◽  
Zong Qiang Zhu ◽  
Yi Nian Zhu
Keyword(s):  
Heavy Metals ◽  
Metal Ion ◽  
Contaminated Water ◽  
Initial Concentration ◽  
Metal Ion Removal ◽  
Ion Removal ◽  
Adsorbed Amount ◽  
Removal Of Heavy Metals ◽  
New Material ◽  
Ammonia Leaching

This study used two types of plant, eucalyptus and bamboo, to produce sorbents for copper (II), cadmium (II), zinc (II), and lead (II) metal ion removal in a water bath shake. The porous biomorphic-genetic composite of hydroxyapatite/carbon with eucalyptus template (PBGC-Fe/C-E) and the porous biomorphic-genetic composite of hydroxyapatite/carbon with bamboo template (PBGC-Fe/C-B) were prepared using eucalyptus and bamboo as plant templates, and through various processes including ammonia leaching, cyclical impregnation using calcium hydroxide and diammonium solutions, and aerobic firing inside muffle furnaces. Tests were conducted on the HAP/C composites to observe their adsorption effects on Cu (II), Zn (II), Pb (II), and Cd (II). The results show that the prepared composites were able to adsorb heavy metals in water effectively. The results indicated that the adsorbed amount of PBGC-Fe/C-E were found to be 16.4371, 4.6725,24.5528, 17.0194 mg/1 for Cu (II), Zn (II), Pb (II) and Cd (II) ions at initial concentration of 50mg/L (25°C), respectively. The adsorbed amount of PBGC-Fe/C-B were found to be 10.5876, 3.9142,21.2463, 13.4721 mg/1 for Cu (II), Zn (II), Pb (II) and Cd (II) ions at initial concentration of 50mg/L (25°C), respectively. The prepared adsorbent is expected to be a new material for the removal of heavy metals from contaminated water.

scholarly journals Optimizing Parameters for the Remediation of Chromium(VI) Contaminated Groundwater on Tamil Nadu Chromates and Chemicals Limited (TCCL) Site of Ranipet, Tamilnadu using Electrocoagulation Process

2021 ◽  
Vol 33 (2) ◽  
pp. 276-280
Author(s):  
B. MUTHUKUMARAN ◽  
VANITHA MURUGAIYAN
Keyword(s):  
Energy Consumption ◽  
Tamil Nadu ◽  
Contaminated Groundwater ◽  
Contaminated Water ◽  
Optimum Conditions ◽  
Applied Current ◽  
Time Duration ◽  
Initial Concentration ◽  
Chromium Vi ◽  
Electrocoagulation Process

This paper presents the effects of variables such as electrode material, electrode distance, pH, initial concentration of Cr(VI), applied current, electrolyte and time duration in the treatment of contaminated groundwater for the removal of Cr(VI) at two different concentrations of 200 and 800 mg/L of Cr(VI) using batch electrocoagulation process. Initially, the conditions were optimized from synthetic contaminated water, which was in congruence with chloride and sulphate ions as present in the contaminated groundwater. The optimum conditions obtained on removal of Cr(VI) from synthetic contaminated water were applied in real Cr(VI) contaminated groundwater collected from a bore well at chromate ore processing residue (COPR) dumpsite. The results of the treated contaminated groundwater were found that all the parameters were within the limits of Pollution Control Board discharge standards. The efficiency and energy consumption on the removal of Cr(VI) from real contaminated groundwater were compared with and without addition of NaCl. The results suggest that the optimum conditions for a 99.99% removal efficiency were initial concentration 200 mg/L of Cr(VI), pH 6.0, applied current 2 A, electrolyte 2 g/L of NaCl, time duration 35 min and energy consumption 2.625 Whr/m3.

scholarly journals EFFECTS OF SILICIC ACID ON ENVIRONMENTAL STABILITY OF SPENT MAGNESIUM-BASED ARSENIC ADSORBENTS

2017 ◽  
Vol 73 (7) ◽  
pp. III_407-III_418
Author(s):  
Hajime SUGITA ◽  
Terumi OGUMA ◽  
Ming ZHANG ◽  
Junko HARA ◽  
Yoshishige KAWABE
Keyword(s):  
Silicic Acid ◽  
Environmental Stability
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