Hydrophilic & hydrophobic presentationnaharislam1
i think it will help the engineering student for their technological knowledge gathering & it is very interesting topic most
of things are natural which teaches us nature how to keep beautifull their own surface. We have learn many things from nature & also should be applied in our life from learning.
Hydrophilic & hydrophobic presentationnaharislam1
i think it will help the engineering student for their technological knowledge gathering & it is very interesting topic most
of things are natural which teaches us nature how to keep beautifull their own surface. We have learn many things from nature & also should be applied in our life from learning.
Generally speaking, super hydrophobic coatings are made from composite materials where one component provides the roughness and the other provides low surface energy. It is made from super hydrophobic (ultra hydrophobicity) materials. A super hydrophobic coating is a thin surface layer that repels water.
The presentation is made as part of introducing some novel technologies in Chemical Engineering. It aims at conveying an overall idea about the Sol-Gel Technology, its underlying processes, applications as well as its future possibilities.
Surface area is an important physical property that influences the reactivity, dissolution, catalysis, and separation of materials. The surface area often must be carefully engineered and measured to optimize specific functions. In this Webinar, our applications lab will explain with real-world examples:
- Physical adsorption technique - BET theory
- Sample preparation – the start of a good measurement
- Calculating specific surface area from gas adsorption on solid surfaces
- Troubleshooting – what happens when things go wrong?
View recorded webinars:
http://bit.ly/particlewebinars
presented to : Dr | Hamdy El-Kady
Physical Chemistry Course 2016-2017
prepared By : Muhammad Mamdouh Abdulsalam
Faculty Of Petroleum Engineering, Suez University
Role of water in Biomaterials· The primary role water plays in bMalikPinckney86
Role of water in Biomaterials
· The primary role water plays in biomaterials is as a solvent system.
· Water is the “universal ether” as it has been termed (Baier and Meyer, 1996), dissolving inorganic salts and large organic macromolecules such as proteins or carbohydrates (solutes) with nearly equal efficiency (Pain, 1982).
· Water is an active participant in biology, which simply could not and would not work the way it does without the special mediating properties of water.
· Moreover, it is widely believed that water is the first molecule to contact biomaterials in any clinical application (Andrade et al., 1981; Baier, 1978).
· This is because water is the majority molecule in any biological mixture, constituting 70 wt % or more of most living organisms, and because water is such a small and agile molecule, only about 0.25 nm in the longest dimension.
· Consequently, behavior of water near surfaces and the role of water in biology are very important subjects in biomaterials science.
· Self-association confers unique properties on water, many of which are still active areas of scientific investigation even after more than 200 years of chemical and physical research applied to water (Franks, 1972).
WATER SOLVENT PROPERTIES
A
C
B
D
FIG. Atomic structure of water illustrating (A) tetrahedral bonding arrangement wherein hydrogen atoms (H, light-colored spheres) are Lewis acid centers and the two lone-pair electrons on oxygen (O, dark-colored spheres) are Lewis base centers that permit water to hydrogen bond with four nearest-neighbor water molecules; (B) electron density map superimposed on an atomic-radius sphere model of water providing a more authentic representation of molecular water; (C) approximate molecular dimensions; and (D) five water molecules participating in a portion of a hydrogen-bond network.
· Hydrogen bonds in water are relatively weak 3–5 kcal/mole associations with little covalent character (Iassacs et al., 1999; Marshall, 1999).
· Hydrogen bonds are quite transient in nature, persisting only for a few tens of picoseconds (Berendsen, 1967; Luzar and Chandler, 1996).
· Modern molecular simulations suggest, however, that more than 75% of liquid-water molecules are interconnected in a three-dimensional (3D) network of three or four nearest neighbors at any particular instant in time (Robinson et al., 1996).
· In chemical terminology, less self-associated water has a greater chemical potential than more self associated water.
· This is why water ice with a complete crystalline network is less dense than liquid water and floats upon unfrozen water, a phenomenon with profound environmental impact.
· Water is amphoteric in this sense because, as illustrated in Figs. 1A and 1D, it can simultaneously share and donate electron density. Hydrogen atoms (the Lewis acids) on one or more adjacent water molecules can accept electron density from the unshared electron pairs on the oxygen atom (the Lewis bases) of another water molec ...
Generally speaking, super hydrophobic coatings are made from composite materials where one component provides the roughness and the other provides low surface energy. It is made from super hydrophobic (ultra hydrophobicity) materials. A super hydrophobic coating is a thin surface layer that repels water.
The presentation is made as part of introducing some novel technologies in Chemical Engineering. It aims at conveying an overall idea about the Sol-Gel Technology, its underlying processes, applications as well as its future possibilities.
Surface area is an important physical property that influences the reactivity, dissolution, catalysis, and separation of materials. The surface area often must be carefully engineered and measured to optimize specific functions. In this Webinar, our applications lab will explain with real-world examples:
- Physical adsorption technique - BET theory
- Sample preparation – the start of a good measurement
- Calculating specific surface area from gas adsorption on solid surfaces
- Troubleshooting – what happens when things go wrong?
View recorded webinars:
http://bit.ly/particlewebinars
presented to : Dr | Hamdy El-Kady
Physical Chemistry Course 2016-2017
prepared By : Muhammad Mamdouh Abdulsalam
Faculty Of Petroleum Engineering, Suez University
Role of water in Biomaterials· The primary role water plays in bMalikPinckney86
Role of water in Biomaterials
· The primary role water plays in biomaterials is as a solvent system.
· Water is the “universal ether” as it has been termed (Baier and Meyer, 1996), dissolving inorganic salts and large organic macromolecules such as proteins or carbohydrates (solutes) with nearly equal efficiency (Pain, 1982).
· Water is an active participant in biology, which simply could not and would not work the way it does without the special mediating properties of water.
· Moreover, it is widely believed that water is the first molecule to contact biomaterials in any clinical application (Andrade et al., 1981; Baier, 1978).
· This is because water is the majority molecule in any biological mixture, constituting 70 wt % or more of most living organisms, and because water is such a small and agile molecule, only about 0.25 nm in the longest dimension.
· Consequently, behavior of water near surfaces and the role of water in biology are very important subjects in biomaterials science.
· Self-association confers unique properties on water, many of which are still active areas of scientific investigation even after more than 200 years of chemical and physical research applied to water (Franks, 1972).
WATER SOLVENT PROPERTIES
A
C
B
D
FIG. Atomic structure of water illustrating (A) tetrahedral bonding arrangement wherein hydrogen atoms (H, light-colored spheres) are Lewis acid centers and the two lone-pair electrons on oxygen (O, dark-colored spheres) are Lewis base centers that permit water to hydrogen bond with four nearest-neighbor water molecules; (B) electron density map superimposed on an atomic-radius sphere model of water providing a more authentic representation of molecular water; (C) approximate molecular dimensions; and (D) five water molecules participating in a portion of a hydrogen-bond network.
· Hydrogen bonds in water are relatively weak 3–5 kcal/mole associations with little covalent character (Iassacs et al., 1999; Marshall, 1999).
· Hydrogen bonds are quite transient in nature, persisting only for a few tens of picoseconds (Berendsen, 1967; Luzar and Chandler, 1996).
· Modern molecular simulations suggest, however, that more than 75% of liquid-water molecules are interconnected in a three-dimensional (3D) network of three or four nearest neighbors at any particular instant in time (Robinson et al., 1996).
· In chemical terminology, less self-associated water has a greater chemical potential than more self associated water.
· This is why water ice with a complete crystalline network is less dense than liquid water and floats upon unfrozen water, a phenomenon with profound environmental impact.
· Water is amphoteric in this sense because, as illustrated in Figs. 1A and 1D, it can simultaneously share and donate electron density. Hydrogen atoms (the Lewis acids) on one or more adjacent water molecules can accept electron density from the unshared electron pairs on the oxygen atom (the Lewis bases) of another water molec ...
Soft matter or soft condensed matter is a subfield of condensed matter comprising a variety of physical systems that are deformed or structurally altered by thermal or mechanical stress of the magnitude of thermal fluctuations. They include liquids, colloids, polymers, foams, gels, granular materials, liquid crystals, and a number of biological materials. These materials share an important common feature in that predominant physical behaviors occur at an energy scale comparable with room temperature thermal energy. At these temperatures, quantum aspects are generally unimportant. Pierre-Gilles de Gennes, who has been called the "founding father of soft matter,"[1] received the Nobel Prize in physics in 1991 for discovering that methods developed for studying order phenomena in simple systems can be generalized to the more complex cases found in soft matter, in particular, to the behaviors of liquid crystals and polymers.[2]
Contents
1 Distinctive physics
2 Applications
3 Research
4 Related
5 See also
6 References
7 External links
2018 - Flexible and porous cellulose aerogels-zeolitic imidazolate framework ...DrChimie
la courbe d'étalonnage peut être configurée en mesurant ou en entrant jusqu'à 10 étalons ou en entrant K et B facteursla courbe d'étalonnage peut être configurée en mesurant ou en entrant jusqu'à 10 étalons ou en entrant K et B facteurs
For more such informative content, go to https://scifitechify.blogspot.com/. Surface chemistry presentation will provide lots of valuable information about its day-to-day applications in real life. It explains concepts of adsorption, absorption, activation energy, Arrhenius equation, colloids, solutions, chemical processes etc.
It also elaborates on specific chemical reactions like peptisation reaction.
Experimental Investigation on Pool Boiling Heat Transfer With Ammonium Dodecy...IJERA Editor
We have so many applications related to Pool Boiling. The Pool Boiling is mostly useful in arid areas to
produce drinking water from impure water like sea water by distillation process. It is very difficult to distill the
only water which having high surface tension. The surface tension is important factor to affect heat transfer
enhancement in pool boiling. By reducing the surface tension we can increase the heat transfer rate in pool
boiling. From so many years we are using surfactants domestically. It is proven previously by experiments that
the addition of little amount of surfactant reduces the surface tension and increase the rate of heat transfer. There
are different groups of surfactants. From those I‟m conducting experimentation with anionic surfactant
Ammonium Dodecyl Sulfate (ADS), which is most human friendly and three times best soluble than Sodium
Dodecyl Sulfate, to test the heat transfer enhancement.
Characterization and Humidity Sensing Application of WO3-SnO2 NanocompositeIOSR Journals
Studies on the sensitivity of the electrical resistance and fabrication process of SnO2 doped WO3
nanometer materials for sensing applications are reported in details .Other properties such as reproducibility,
aging and hysteresis were also recorded and found satisfactory. The sensing mechanism was discussed based on
their annealing temperature, composition, crystallite size, surface area and porosity of the sensing element. In
general, at low humidity, surface area and water adsorption plays the dominant role, while at high humidity,
mesopore volume and capillary condensation become important. At the annealing temperature 600°C, sample 3
weight % of SnO2 doped WO3 nanocomposites have been prepared through solid-state reaction route, shows
average sensitivity of 18.61 MΩ/%RH in the 15%-95% RH range, lower hysteresis, less effect of ageing and
high reproducibility. It was observed that as resistance of the pellets continuously decreased when relative
humidity in the chamber was increased from 15% to 95%. As calculated from Scherer’s formula, crystallite size
for the sensing elements of SnO2 doped WO3 are in 11–234 nm range, respectively.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
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Water billing management system project report.pdfKamal Acharya
Our project entitled “Water Billing Management System” aims is to generate Water bill with all the charges and penalty. Manual system that is employed is extremely laborious and quite inadequate. It only makes the process more difficult and hard.
The aim of our project is to develop a system that is meant to partially computerize the work performed in the Water Board like generating monthly Water bill, record of consuming unit of water, store record of the customer and previous unpaid record.
We used HTML/PHP as front end and MYSQL as back end for developing our project. HTML is primarily a visual design environment. We can create a android application by designing the form and that make up the user interface. Adding android application code to the form and the objects such as buttons and text boxes on them and adding any required support code in additional modular.
MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software. It is a stable ,reliable and the powerful solution with the advanced features and advantages which are as follows: Data Security.MySQL is free open source database that facilitates the effective management of the databases by connecting them to the software.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
Heap Sort (SS).ppt FOR ENGINEERING GRADUATES, BCA, MCA, MTECH, BSC STUDENTS
Hydrophilic & hydrophobic assignment
1. Bangladesh University of Engineering Technology
Assignment On
Nano Materials for Hydrophilic & Hydrophobic
Surfaces
Subject Of:
Nano-ceramics
Code: GCE6602
Submitted To:
Professor Dr. A. K. M Abdul Hakim
Dept of Glass and Ceramics Engineering
Submitted By:
M. Sc in GCE
Shamsun Nahar
ID: 1017172030
Date of Submission:
03-10-2018
2. Definition of Hydrophilicity:
Hydrophilic is a molecule or other molecular entity that is attracted to water
molecules and tends to be dissolved by water. It refers to having a strong affinity
for water. Something that is hydrophilic is soluble in water and dissolves into
water very easily. Hydrophilic is the opposite of hydrophobic.
Hyrophilic Surface
3. The hydrophilic concept is used in many industries. For example, hydrophilic
membrane filtration is used in several industries to filter various substances such
as:
Bacteria
Viruses
Particulates
Drugs
Contaminates
Hydrophilic coatings are particularly effective in environments of excessive
condensation and to protect the exchanger from the corrosive effect of water.
Hydrophilic coating also exhibits a fine performance in providing protection
against water in high temperature and salty environments.
Since hydrophilic substances attract and hold moisture, it causes a molecular layer
of moisture on the surface, which leads to corrosion. Hydrophilic substances like
chlorides or sulfates promote corrosion by destroying surface film of metal or
alloys. For example, the surface film that usually forms on magnesium alloys, is
exposed to the atmosphere, and gives limited protection from further attack.
Corrosion of magnesium alloys increases with relative humidity and contact with
hydrophilic substances.
Definition of Hydrophobicity:
Hydrophobic molecules are molecules that do not have a charge, meaning they are
non-polar. By lacking a charge, these molecules do not have any charge-to-charge
interactions that will allow them to interact with water. Hydrophobic materials
often do not dissolve in water or in any solution that contains a
largely aqueous (watery) environment. This characteristic of being hydrophobic -
or non-polar - is important for many of the molecules found in nature, in other
organisms, and even within our own bodies.
4. The word hydrophobic comes from the Greek roots hydro- (meaning water) and -
phobia (meaning fearing or hating). The word hydrophobic describes the fact that
nonpolar substances don't combine with water molecules.
Examples of hydrophobic molecules include the alkenes, oils, fats, and greasy
substances in general. Hydrophobic materials are used for oil removal from water,
the management of oil spills, and chemical separation processes to remove non-
polar substances from polar compounds.
Hydrophobic is often used interchangeably with lipophilic, "fat-loving". However,
the two terms are not synonymous. While hydrophobic substances are usually
lipophilic, there are exceptions, such as the silicones and fluorocarbons.
Hydrophilic & Hydrophobic Molecule:
Water is a polar molecule. Polar molecules are molecules that have partial charges
due to uneven bonding. The oxygen atom in a water molecule is highly
electronegative, which means that it will pull the electrons in a bond closer to it.
This, in turn, makes oxygen partially negative and hydrogen partially positive.
Hydrophobic Surface
Hydrophobic Surface
5. Hydrophilic molecules (and portions of molecules) can be contrasted with
hydrophobic molecules (and portions of molecules). In some cases, both
hydrophilic and hydrophobic properties occur in a single molecule. An example of
these amphiphilic molecules is the lipids that comprise the cell membrane. Another
example is soap, which has a hydrophilic head and a hydrophobic tail, allowing it
to dissolve in both water and oil.
Superhydrophilicity & Superhydrophobicity:
Superhydrophilicity refers to the phenomenon of excess hydrophilicity, or
attraction to water; in superhydrophilic materials, the contact angle of water is
equal to zero degrees. This effect was discovered in 1995 by the Research Institute
of Toto Ltd. for titanium dioxide irradiated by sunlight. Under light irradiation,
water dropped onto titanium dioxide forms no contact angle (almost 0 degrees)
6. Superhydrophilic material has various advantages. For example, it can defog glass,
and it can also enable oil spots to be swept away easily with water. Such materials
are already commercialized as door mirrors for cars, coatings for buildings, self-
cleaning glass, etc.
Several mechanisms of this superhydrophilicity have been proposed by
researchers. One is the change of the surface structure to a metastable structure,
and another is cleaning the surface by the photodecomposition of dirt such
as organic compounds adsorbed on the surface, after either of which water
molecules can absorb to the surface.
Superhydrophobic surfaces are highly hydrophobic, i.e., extremely difficult
to wet. The contact angles of a water droplet on an ultra hydrophobic material
exceed 150°. This is also referred to as the lotus effect, after the superhydrophobic
leaves of the lotus plant. A droplet striking these kinds of surfaces can fully
rebound like an elastic ball or pancake.
Superhydrophilic surface
Superhydrophobic Surface
7. Frank Schellenberger and his colleagues from the Max Planck Institute for
Polymer Research in Germany have performed the first microscopic imaging of
how a contact line advances on a rough superhydrophobic surface [3]. The team
found that commonly used definitions of superhydrophobicity based on the
advancing contact angle are unreliable. Instead, they propose using the receding
contact angle, which gives consistent values between macroscopic and microscopic
techniques. This redefinition could be embraced by designers looking for more
efficient superhydrophobic materials.
Condition of Superhydrophilic & Superhydrophobic
Surfaces:
Young’s Equation for superhydrophilicity:
The shape of a liquid–vapor interface is determined by the Young–Laplace
equation, with the contact angle playing the role of a boundary condition via
the Young equation.
The theoretical description of contact arises from the consideration of
a thermodynamic equilibrium between the three phases: the liquid phase (L),
the solid phase (S), and the gas or vapor phase (G) (which could be a mixture of
ambient atmosphere and an equilibrium concentration of the liquid vapor). (The
"gaseous" phase could be replaced by another immiscible liquid phase.) If the
solid–vapor interfacial energy is denoted by the solid–liquid interfacial energy
by , and the liquid–vapor interfacial energy (i.e. the surface tension) by then
Superhydrophobic Surface
8. the equilibrium contact angle is determined from these quantities by the Young
equation:
- - = 0
The contact angle can also be related to the work of adhesion via the Young–Dupré
equation:
=
Where is the solid – liquid adhesion energy per unit area when in the medium
V.
Diagram for superhydrophilicity conditions equation
Dynamic contact of droplet with superhydrophobic surface in
conditions favors icing:
Flight like droplet impact with superhydrophobic substrate in conditions favor
icing is discussed in this work. Test stand with fast camera and equipment
eligible to obtain temperatures and humidity at different ranges, lead to results
which can prove, that superhydrophobic surface might be good ice repellent
substrate. The influence of air humidity on droplet freezing was confirmed.
9. Various studies have shown that as well as having ultra water repellency the
surfaces have reduced ice adhesion and can delay water freezing. However, the
structure or texture (roughness) of the superhydrophobic surface is subject to
degradation during the thermo cycling or wetting process. This degradation can
impair the superhydrophobicity and the icephobicity of those coatings. In this
review, a brief overview of the process of droplet freezing on superhydrophobic
coatings is presented with respect to their potential in anti-icing applications. To
support this discussion, new data is presented about the condensation of water onto
physically decorated substrates, and the associated freezing process which impacts
on the freezing of macroscopic droplets on the surface.
Case Study for Superhydrophilic: Photocatalytic
ActivityTiO2 and Photo-Hydrophilic function
TiO2 containing visible-light-active nano-sized heterostructures based on coupled
oxides generally exploit oxide semiconductors with band gap energy lower than
that of TiO2 and with a more negative redox potential of conduction band (CB)
electrons in order to absorb visible light and inject photo-generated electrons in
TiO2 CB. Under these conditions, the CB electrons in TiO2 can initiate the photo-
reduction processes responsible for pollutant removal. In particular, the TiO2/WO3
couple has received much attention for improving the Photocatalytic properties of
TiO2 under visible light irradiation, since WO3 can be regarded as an electron
accepting species. Indeed, both valence and conduction band of WO3 lie below
those of TiO2. In addition, WO3 has a narrow band gap (~2.8 eV). Therefore,
under visible light, photo-generated electrons can be excited from the valence band
(VB) to the CB of WOx and the holes in the VB of WOx can be transferred to
TiO2 or remain in the VB of WOx.
10. Synthesized WO3/TiO2 by a sol-gel process using solutions of Ti(OBu)4 and
solutions of ammonium tungstate. Subsequently, the product was activated in a
single-step thermal treatment in a vacuum to enhance the Photocatalytic activity in
the visible region. Recently, prepared TiO2/WO3 composites with different
contents of tungsten oxide by a microwave-assisted hydrothermal method, an
environmentally friendly and novel process. Specifically, they have prepared
TiO2/WO3 from TiCl4 and Na2WO4 without using any organic species [35].
Furthermore, a promising strategy to enhance the visible-light Photocatalytic
performance is to combine Bi2WO6 with TiO2. The photo catalyst based on the
TiO2/Bi2WO6 hetero-junction has been synthesized by a simple and practical
liquid phase method. The hybrid nanocrystals are characterized by a special
morphology with the TiO2 particles coating the surface of the flower-like Bi2WO6
microspheres. The obtained hetero-structure has demonstrated improved light
harvesting efficiency and effective electron/hole pair separation, which results in
improved photo activity. Also, BiFeO3/TiO2 and ZnFeO4/TiO2 are favorable
materials to develop a high-efficiency photo catalyst active in the visible region
[1]. Core-shell structured BiFeO3/TiO2 nanocomposites have been synthesized by
a hydrothermal process, followed by hydrolysis precipitation of tetra butyl titanate
(TBOT). The results indicate that BiFeO3/TiO2 nanocomposites have good
visible-light absorption properties, which should be induced by Fe or Bi/Ti inter-
diffusion in the interfaces. ZnFeO4/TiO2-coupled semiconductors have been
successfully fabricated by a two-step process of anodization and a vacuum-assisted
impregnation method, followed by annealing. In this case, the ZnFe2O4
sensitization enhances the probability of photo-induced charge separation and
extends the range of the photo-response of TiO2 nano-tube arrays from the UV to
the visible region.
Case Study for Superhydrophobic: manganese oxide
polystyrene for superhydrophobic surfaces
Superhydrophobic transparent thin films using Mn doped zinc oxide (Mn/ZnO)
and polystyrene (PS) composites have been synthesized successfully by chemical
solution method. The nanocomposites thin films were fabricated by using Mn/ZnO
and PS mixture in toluene, followed by film casting on glass substrate. For a
comparison ZnO nanoparticles thin film was also prepared with PS. Mn/ZnO
nanostructures have been synthesized by hydrothermal method using
hexamethylenetetramine (HMTA) as a capping agent. The XRD analysis shows
that the development of hexagonal wurtzite structure of Mn/ZnO with preferred
(101) orientation. SEM analysis shows that Mn/ZnO nanorods have been
11. uniformly dispersed in the PS matrix. Water contact angle (WCA) was found as
107° and 151° for the ZnO/PS and Mn doped ZnO/PS thin film, respectively. The
transparency of the Mn doped ZnO/PS films are also large (∼90%) as compared to
ZnO/PS film (∼80%) which is attributed to enhanced energy band gap of ZnO
after Mn doping. The larger contact angle (WCA ∼151°) in the Mn/ZnO/PS thin
film has been recognized to the rough surface of PS thin film due to the presence
of Mn/ZnO nanorods. The present process is very simple and embraces ability for
extensive applications for making super hydrophobic transparent surfaces.
Lotus Effect or Self-cleaning by Superhydrophobic
Surfaces
Some plant leaves just can’t get wet or dirty! Lotus plants have superhydrophobic
surfaces. Water drops that fall onto them bead up and roll off. These leaves not
only stay dry, but the droplets pick up small particles of dirt as they roll, so that the
lotus leaves are even self-cleaning.
12. Figure: Lotus Effect
How Does It Stay Dry?
The lotus leaves have nano-structures on their surfaces. These nanostructures are
coated with hydrophobic wax crystals approximately 1 nm in diameter. This makes
the surface at the nanoscale quite rough. This rough surface is more hydrophobic
than a smooth surface would be.
Figure: self-cleaning
13. Application of Hydrophilic Surfaces:
1. Self-cleaning glass
2. Anti-fogging glass
3. Waste water treatment
4. anti-icing: Low surface energy or liquid-infused
5. Oil and Gas Applications
6. Anti-frosting glass
7. Anti-fouling coating
Application of Hydrophobic Surfaces:
self-cleaning surface
anti-icing surfaces
drag reduction
enhanced heat transfer
a thin air layer that reduces attractive interactions between the solid surface
and the liquid
Water proof circuit
Solar Panels.
Dirt cleaning
Biomedical Application:
to control protein adsorption
cellular interaction
bacterial growth
drug delivery devices
diagnostic tools