Removal efficiency calculated beforehand: QSAR enabled predictions for nanofiltration and advanced oxidation

2013 ◽  
Vol 13 (6) ◽  
pp. 1425-1436 ◽  
Author(s):  
D. Vries ◽  
B. A. Wols ◽  
P. de Voogt
Keyword(s):  
Process Model ◽  
Prediction Models ◽  
Uv Light ◽  
Removal Rate ◽  
Chemical Properties ◽  
Chemical Mechanisms ◽  
Physico Chemical ◽  
Share Data ◽  
Rejection Coefficient ◽  
Definition Of

The efficiency of water treatment systems in removing emerging (chemical) substances is often unknown. Consequently, the prediction of the removal of contaminants in the treatment and supply chain of drinking water is of great interest. By collecting and processing existing chemical properties of contaminants, QSARs (quantitative structure-activity relationships) for typical removal parameters can be constructed. Depending on the definition of the predicted endpoint, QSARs are (1) embedded in a process model suite, where they serve to predict a model parameter and the total, hybrid model predicts a removal rate or (2) used to directly predict, e.g., the removal rate, or a rejection coefficient for membrane systems. The different types of resulting prediction models, ranging from mechanistic (causal) to empirical (data-based), allow for hypothesis testing of current physico-chemical mechanisms and interactions between the contaminant, the type of water and the materials or energy (e.g. UV light) of the removal barrier. Two case studies illustrate this viewpoint and also pinpoint that, firstly, QSAR development, validation and residual analysis stress the linkage between the QSAR endpoints and process model predictions, and secondly, they lay bare the need to share data, algorithms and models.

scholarly journals Groundwater physico-chemical properties and water quality changes in shallow aquifers in arid saline wetlands, Ouargla, Algeria

2021 ◽  
Vol 11 (5) ◽  
Author(s):  
Fethi Medjani ◽  
Mohamed Djidel ◽  
Sofiane Labar ◽  
Louiza Bouchagoura ◽  
Chouaib Rezzag Bara
Keyword(s):  
Water Quality ◽  
Chemical Properties ◽  
High Water ◽  
Quality Changes ◽  
Shallow Aquifers ◽  
Shallow Water Table ◽  
Chemical Mechanisms ◽  
Desert Region ◽  
Physico Chemical ◽  
Hypersaline Water

AbstractShallow aquifers are vulnerable to natural geogenic processes as well as anthropogenic influences, and this is especially apparent in desert regions. Within arid and hyperarid climates, evaporation is a controlling hydrologic process leads to an important increase in the concentration of dissolved minerals of both surface water and groundwater. In groundwater, this increase is not only dependent on shallow water table depth, but also on the hydraulic properties of sediments present within the unsaturated zone of the aquifer itself. The main objective of this research is to investigate possible mechanisms that might influence water quality changes under seasonal conditions in shallow aquifers situated within the Saharan desert region of Algeria. In this work, we focus on observed changes in hydrogeochemical characteristics, and the possible responsible processes. Under arid conditions, high water mineralization results in hypersaline water or brine solution formation within shallow aquifers. Due to active physico-chemical mechanisms such as Na+/Ca2+ ion exchange, the successive precipitation of calcite, gypsum, mirabilite or blœdite and halite is induced. Biological processes were also observed as prevalent; evidenced by large measured variations in CO2 load concentrations. These processes contributed to an inverse relationship between CO2 and O2 concentrations within the shallow aquifers studied.

scholarly journals Decolorization of crystal violet over TiO2 and TiO2 doped with zirconia photocatalysts

2017 ◽  
Vol 71 (3) ◽  
pp. 259-269 ◽  
Author(s):  
Marija Vasic ◽  
Marjan Randjelovic ◽  
Jelena Mitrovic ◽  
Nikola Stojkovic ◽  
Branko Matovic ◽  
...  
Keyword(s):  
Crystal Violet ◽  
Uv Light ◽  
Sol Gel ◽  
Chemical Properties ◽  
Dye Decolorization ◽  
Operational Parameters ◽  
Physico Chemical ◽  
Irradiation Treatment ◽  
Catalytic Material ◽  
Reaction Cycles

Titania based catalyst and TiO2 doped with zirconia were prepared by modified sol?gel method. The synthesized catalysts samples were characterized by BET, XRD, SEM and FTIR techniques. Photocatalytic activity was tested in the reaction of crystal violet (CV) dye decolorization/decomposition under UV light irradiation. The effect of several operational parameters, such as catalyst dosage, initial dye concentrations, duration of UV irradiation treatment and number of reaction cycles were also considered. The obtained results indicated faster dye decolorization with the increase of the catalyst amount and a decrease of initial CV concentrations. An influence of doping with zirconia on the physico-chemical properties of bare titania was studied. The doping procedure had affected photocatalytic properties of the final catalytic material, and had improved photocatalytic performances of doped catalyst on crystal violet decolorization/degradation in comparison to bare titania.

Structural and Photocatalytic Property of CaTiO3 Nanosphere

2020 ◽  
Vol 979 ◽  
pp. 169-174 ◽  
Author(s):  
C. Karthikeyan ◽  
M. Thamima ◽  
S. Karuppuchamy
Keyword(s):  
Dye Degradation ◽  
Uv Light ◽  
Chemical Properties ◽  
Photocatalytic Property ◽  
Advanced Characterization ◽  
Morphological Studies ◽  
Physico Chemical ◽  
Raman Study ◽  
Ft Ir ◽  
Xrd Patterns

The nanostructured photocatalysts are the most promising materials for the degradation of toxic dyes. Particularly, CaTiO3 has been used in several applications including catalytic, optical, biological and electronic. In this present study, perovskite structured CaTiO3 nanomaterials have been synthesized by microwave irradiation method. The physico-chemical properties of the prepared CaTiO3 nanomaterials were studied by various advanced characterization techniques. The XRD patterns confirm the presence of perovskite structure of the prepared nanomaterials. FT-IR analysis confirms the presence of Ca-Ti-O vibrational bonds. Micro Raman study display the existence of O-Ca-Ti-O with B1g mode of vibrations. Morphological studies revealed the presence of truncated nanospheres. The dye degradation property of prepared CaTiO3 was investigated by Malachite green (MG) by UV-light.

scholarly journals Nanosystems in Cosmetic Products: A Brief Overview of Functional, Market, Regulatory and Safety Concerns

Pharmaceutics ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1408
Author(s):  
Chiara Ferraris ◽  
Clara Rimicci ◽  
Sara Garelli ◽  
Elena Ugazio ◽  
Luigi Battaglia
Keyword(s):  
Chemical Properties ◽  
Chemical Characterization ◽  
Accidental Exposure ◽  
Safety Concerns ◽  
Physico Chemical ◽  
Cosmetic Ingredients ◽  
Exposure Routes ◽  
Definition Of ◽  
Skin Retention ◽  
Regulatory Landscape

Nanosystems exhibit various innovative physico-chemical properties as well as a range of cosmetic functions, including increased skin retention for loaded compounds. The worldwide nano-market has therefore been consistently extensive in recent decades. This review summarizes the most important properties of nanosystems that are employed in cosmetics, including composition, functions and interactions with skin, with particular attention being paid to marketed products. Moreover, the worldwide regulatory landscape of nanomaterials used as cosmetic ingredients is considered, and the main safety concerns are indicated. In general, advanced physico-chemical characterization is preliminarily needed to assess the safety of nanomaterials for human health and the environment. However, there is currently a shortfall in global legislation as a universally accepted and unambiguous definition of a nanomaterial is still lacking. Therefore, each country follows its own regulations. Anyhow, the main safety concerns arise from the European context, which is the most restrictive. Accordingly, the poor dermal permeation of nanomaterials generally limits their potential toxic effects, which should be mainly ascribed to unwanted or accidental exposure routes.

scholarly journals Choosing the exponent in the definition of the connectivity index

2001 ◽  
Vol 66 (9) ◽  
pp. 605-611 ◽  
Author(s):  
Ivan Gutman ◽  
Mirko Lepovic
Keyword(s):  
Carbon Atom ◽  
Topological Index ◽  
Organic Molecules ◽  
Molecular Graph ◽  
Chemical Properties ◽  
Connectivity Index ◽  
Physico Chemical ◽  
Definition Of ◽  
Molecular Branching ◽  
Suitable Measure

Let ?v denote the degree of the vertex v of a molecular graph G. Then the connectivity index of G is defined as C (?) = G (?,C) = ? (?u?v)?, where the summation goes over all pairs of adjacent vertices. The exponent ? is usually chosen to be equal to -1/2, but other options were considered as well, especially ?=-1. We show that whereas C(-1/2) is a suitable measure of branching of the carbon-atom skeleton of organic molecules, and thus applicable as a topological index for modeling physico-chemical properties of the respective compounds, this is not the case with C(-1). The value of ? is established, beyond which C(?) fails to correctly reflect molecular branching.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

Sign in / Sign up

Export Citation Format

Share Document