scholarly journals Experimental modeling and optimization for the reduction of hexavalent chromium in aqueous solutions using ascorbic acid

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qammer Zaib ◽  
Hung Suck Park ◽  
Daeseung Kyung
Keyword(s):  
Ascorbic Acid ◽  
Humic Acid ◽  
Aqueous Solutions ◽  
Tap Water ◽  
Hard Water ◽  
Contaminated Water ◽  
Optimal Dosage ◽  
Statistical Experimental Design ◽  
Experimental Parameters ◽  
Acid Dosage

AbstractIn this study, we investigated the reduction of toxic Cr(VI) to less toxic Cr(III) using ascorbic acid in various aqueous solutions: deionized water, synthetic soft water, synthetic hard water, and real tap water. The experiments were performed using a statistical experimental design. Response surface methodology (RSM) was used to correlate Cr(VI) reduction (response variable) with experimental parameters such as initial Cr(VI) concentration, humic acid concentration, and ascorbic acid dosage. The empirical model obtained from the experiments was used to estimate and optimize the quantity of ascorbic acid required for the reduction of ≥ 99% Cr(VI) in water. The optimized dosages of ascorbic acid were predicted and experimentally validated for > 99.5% reduction of Cr(VI) (1, 10, 20, and 100 mg/L) in the solutions. Even a solution containing an initial Cr(VI) concentration of 100 mg/L was reduced in concentration ≥ 99.9% with optimal dosage of ascorbic acid (500 mg/L) in the presence of 20 mg/L humic acid. Moreover, the reaction kinetics (kobs-Cr(VI) = 0.71 mM−1 s−1) were sufficient to reduce the ≥ 99.9% Cr(VI) in 20 min. This study sheds new light on the effect of ascorbic acid on Cr(VI) reduction, and provides knowledge fundamental to optimize treatment of Cr(VI) contaminated water to environmentally acceptable endpoints.

scholarly journals Insecticidal effects of insecticide, fungicide, complex fertilizer and wetting agent combinations depending on water hardness

2009 ◽  
Vol 24 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Slavica Vukovic ◽  
Dusanka Indjic ◽  
Vojislava Bursic ◽  
Dragana Sunjka ◽  
Mila Grahovac
Keyword(s):  
Colorado Potato Beetle ◽  
Tap Water ◽  
Biological Effects ◽  
Water Hardness ◽  
Hard Water ◽  
Wetting Agent ◽  
Simultaneous Occurrence ◽  
Agricultural Practice ◽  
Potato Beetle ◽  
Novi Sad

Simultaneous occurrence of different harmful species in agricultural practice necessitates that different plant protection chemicals be applied at the same time (tank mix). Mix components differ in purpose, mode of action and/or formulation, while addition of no pesticide components (complex fertilizers, adjuvant and wetting agents) is widely practiced today. However, data concerning the effects of water quality used for preparation of working liquids on the biological effects of pesticides is still scarce. Therefore, the objective of this study was to determine insecticidal effects as depending on components used in mixes and water hardness. The effects of mixtures of thiametoxam (Actara 25-WG 0,07kg/ha) with azoxystrobin (Quadris 0.75 l/ha), mancozeb (Dithane M-70 2.5 kg/ha), a complex fertilizer (Mortonijc plus 3 kg/ha) and a wetting agent (Silwet L-77), depending on the components and water hardness (slightly hard (15.4 d?) - tap water from Novi Sad, and very hard (34.7 d?) - well water from Adica, a Novi Sad suburb), were determined in a bioassay based on adult mortality rate of the first generation of Colorado potato beetle (Leptinotarsa decemlineata Say). The mixtures were applied by a flooding method. The trial was set up to include four replications. Insecticidal effects were determined 24 h and 48 h after exposure. Thiametoxam effectiveness 24 h and 48 h after application in slightly hard water was 100% when the insecticide was applied alone and in double and triple mixes with the fungicides, complex fertilizer and wetting agent, showing no dependency on mix components. The tested adult population of Colorado potato beetle demonstrated high susceptibility to thiametoxam, while the other components had no impact in slightly hard water. In very hard water, 24 h after application, the insecticidal effect had the same level of significance to thiametoxam in double and triple mixes, with an exception of thiametoxam+mancozeb+Mortonijc plus and thiametoxam+mancozeb+wetting agent combinations, which showed significantly lower efficacy. After 48 h, substantially lower effectiveness, in comparison with the sole insecticide and other combinations, was only observed in thiametoksam+mancozeb+Mortonjic plus combination. Significantly lower efficacy of that combination is probably due to an incompatibility of the macozeb preparation and the complex fertilizer containing boron (B), which was evidenced only in very hard water.

scholarly journals Adsorption Study for Trifluralin on Iraqi ? –Alumina

2012 ◽  
Vol 9 (1) ◽  
pp. 153-159 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Adsorption Isotherm ◽  
Aqueous Solutions ◽  
Contact Time ◽  
Adsorption Process ◽  
Kinetic Equations ◽  
Adsorption Study ◽  
Adsorption Capacities ◽  
Experimental Parameters ◽  
Freundlich Adsorption Isotherm ◽  
Equilibrium Adsorption Isotherm

Equilibrium adsorption isotherm for the removal of trifluralin from aqueous solutions using ? –alumina clay has been studied. The result shows that the isotherms were S3 according Giels classification. The effects of various experimental parameters such as contact time, adsorbent dosage, effect of pH and temperature of trifluralin on the adsorption capacities have been investigated. The adsorption isotherms were obtained by obeying freundlich adsorption isotherm with (R2 = 0.91249-0.8149). The thermodynamic parameters have been calculated by using the adsorption process at five different temperature, the values of ?H, ?G and ?S were (_1.0625) kj. mol-1, (7.628 - 7.831) kj.mol-1 and (_2.7966 - _2.9162) kg. k-1. mol-1 respectively. The kinetic study of adsorption process has been studied depending on three kinetic equations: 1- Allergen equation 2- Morris –weber eguation 3- Reichenberg eguation. In general, the result shows the isotherm were on ?- alumina according to Giels classification.? –alumina and thermodynamic

Accumulation of perfluoroalkyl substances in lysimeter-grown rice in Japan using tap water and simulated contaminated water

Chemosphere ◽  
2019 ◽  
Vol 231 ◽  
pp. 502-509 ◽  
Author(s):  
Eriko Yamazaki ◽  
Sachi Taniyasu ◽  
Kosuke Noborio ◽  
Heesoo Eun ◽  
Pooja Thaker ◽  
...  
Keyword(s):  
Tap Water ◽  
Perfluoroalkyl Substances ◽  
Contaminated Water

scholarly journals Low-Pressure Membrane for Water Treatment Applications

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Huda AlFannakh ◽  
Heba Abdallah ◽  
S. S. Ibrahim ◽  
Basma Souayeh
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Drinking Water ◽  
Humic Acid ◽  
Tap Water ◽  
Permeate Flux ◽  
Membrane Performance ◽  
Polyethersulfone Membrane ◽  
Contaminated Drinking Water

Three ultrafiltration membranes were prepared using phase separation techniques. The membranes were characterized by scan electron microscope, porosity, pore size distribution measurement, and mechanical properties. The membrane performance was carried out using synthetic solutions from humic acid and tap water to express the contaminated drinking water. The polyvinylidene difluoride (M2) has the highest tensile strength 33.2 MPa with elongation of 52.3%, while polyacrylonitrile (M3) has the lowest mechanical properties, tensile strength 16.4 MPa with elongation of 42.7%. Polyethersulfone membrane (M1) provides the highest removal of humic acid, which was 99.5, 98.8, and 98.2% using feed concentrations 0.1, 0.3, and 0.5 g/l, respectively, while M3 provides the highest permeate flux which was 250, 234.4, and 201.4 l/m2 h using feed concentrations 0.1, 0.3, and 0.5 g/l, respectively. Analysis of water samples indicates that the prepared membranes can be used to treat the contaminated drinking water which produced the high quality of drinking water after treatment.

Pseudomonacidal Activity of Phenolic Disinfectants in Hard Water

1974 ◽  
Vol 57 (4) ◽  
pp. 880-884
Author(s):  
Murray Winicov ◽  
William Schmidt ◽  
Muriel Palochak
Keyword(s):  
High Activity ◽  
Active Ingredient ◽  
Total Phenolics ◽  
Tap Water ◽  
Hard Water ◽  
Total Phenolic ◽  
Magnesium Ions ◽  
Testing Laboratories ◽  
Confirmation Test ◽  
Test Organisms

Abstract Claims for pseudomonacidal activity under use conditions must be validated by hard water performance. Effective phenolic products can be formulated by using o-phenylphenol (OPP) as the principal active ingredient. In tap water containing calcium or magnesium ions, OPP is more effective than any high phenol coefficient phenolic ingredient. Such OPP compositions as are properly formulated with high activity phenolics require a use-dilution concentration providing at least 450 ppm OPP and not less than 750 ppm total phenolics to pass the AOAC use-dilution confirmation test, 4.011, against the 3 principal test organisms in the presence of 400 ppm hard water. Phenolic-based disinfectant products, providing use-dilution OPP concentrations up to 600 ppm and total phenolic concentrations up to 900 ppm, with validated hard water claims are now commercially available. An OPP standard formula is proposed which can be diluted to provide pass/fail usedilutions–a step in the direction of achieving uniformity among different testing laboratories.

Humic Acid Functionalized - Silver Nanoparticles as Nanosensor for Colorimetric Detection of Copper (II) Ions in Aqueous Solutions

2020 ◽  
Vol 831 ◽  
pp. 142-150
Author(s):  
Edgar Clyde R. Lopez ◽  
Michael Angelo Zafra ◽  
Jon Nyner L. Gavan ◽  
Emil David A. Villena ◽  
Francis Eric P. Almaquer ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Humic Acid ◽  
Aqueous Solutions ◽  
Limit Of Detection ◽  
Colorimetric Detection ◽  
Hydrodynamic Diameter ◽  
Limit Of Quantification ◽  
Local Surface Plasmon Resonance ◽  
Optical Absorbance ◽  
Absorbance Spectra

Humic acid - functionalized silver nanoparticles (HA-AgNPs) were successfully synthesized and used to detect Cu (II) ions in aqueous solutions. The HA-AgNPs was shown to have an average hydrodynamic diameter of 101.4 nm and a polydispersity index of 0.447. The absorbance spectra of HA-AgNPs showed the characteristic local surface plasmon resonance (LSPR) peak of AgNPs at 408.3 nm. Addition of Cu (II) in the HA-AgNPs led to their agglomeration as evidenced by the change in their surface morphology and their corresponding optical absorbance spectra. The synthesized HA-AgNPs showed a strong linear response for Cu (II) concentrations in the range of 0.00 – 1.25 mM with a limit of detection (LoD) of 4.4428 ± 0.1091 mg L-1, a limit of quantification (LoQ) of 14.8094 ± 0.3636 mg L-1, and a limit of blank (LoB) of 0.1214 ± 0.0065 mg L-1. Statistical analysis showed that this calibration curve could be used to quantify Cu (II) concentrations within a 95% confidence level. Furthermore, HA-AgNPs was found to be selective for Cu (II) detection based on the selectivity study against common metal ions found in drinking water. This shows that the synthesized HA-AgNPs can be used as an environment-friendly colorimetric nanosensor for rapid and point-of-need quantification of Cu (II) ions in aqueous media.

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