Osmosis: The Molecular Theory

Larry Howlett

Description

Finally: After 250 years, a solution to this intriguing and important phenomena of osmosis has been found. Many other solutions have been proposed, no others fully explain the process and the many applications. This book introduces a new understanding of osmosis, solids, liquids, and vapor pressure and more....

For those that already understand osmosis, we suggest that you begin with the last chapter. The first chapters may sound like heresy. For others, beginning with the first chapter will take you through the many levels of understanding that we followed to develop the Molecular Theory of Osmosis

Sujets

• Sciences et techniques
• Biotechnology
• Science

Informations

• Publié par: eBookIt.com
• Date de parution: 10 décembre 2013
• Nombre de lectures: 0
• EAN13: 9781628473759
• Langue: English

Extrait

Osmosis
The Molecular Theory
by
Larry D. Howlett

Copyright 2014 Larry Howlett,
All rights reserved.
 
 
Published in eBook format by eBookIt.com
Converted by http://www.eBookIt.com
 
 
ISBN-13: 978-1-6284-7375-9
 
 
No part of this book may be reproduced in any form or by any electronic or mechanical means including information storage and retrieval systems, without permission in writing from the author. The only exception is by a reviewer, who may quote short excerpts in a review.
 
 
Chapter 2 by permission from ASME
Copyright 2003 IMECE2003-55040
The Theory of Osmosis
Chapter 4 by permission from ASME
Copyright 2006 IMECE2006-13695
Osmosis, Characteristic of Liquid at an Interface
Copyright Larry D. Howlett HTMD Engineering
DeKalb, IL 2013
All rights reserved.
Preface
Osmosis is not a normal word or thought for engineers. Several interesting career situations led to a path where my skills were applied on basic engineering problems. One of these was a design and build seed storage warehouse. Beginning with an open slate for all parameters, we had the opportunity to research the literature for optimum seed storage environments and develop the equipment to maintain these conditions.
 
We noticed a control system problem and corrected it by using temperature and vapor pressure as control variables. The measured temperature and relative humidity were used to calculate the moisture vapor pressure using a simple algorithm.
 
This successful modification to the controls suggested that vapor pressure might be an important variable in defining seed storage. Others had introduced van’t Hoff’s theory of osmosis as an important factor in defining seed storage conditions. The magnitude of vapor pressure is insignificant compared to value of van’t Hoff’s osmotic pressure.
 
A conflict was thus established between the vapor pressure model and the osmotic pressure approach used by others. By the time that we discovered this conflict, we had already thoroughly tested our approach and had successful operating equipment.
 
Therefore, we studied osmosis. It was an intriguing problem. An experiment by J.A.Nollet in 1748 showed that water flowed uphill into wine. A large pressure had to be applied to the wine to stop the flow. After 150 years, van’t Hoff found the first thermodynamic explanation of the phenomena. But, van’t Hoff’s work has been challenged by many during the last 110 years.
 
Our initial paper on osmosis clearly incorporated van’t Hoff’s work into a complete theory for osmosis. Later papers provide thermodynamic support of the vapor pressure model and provide a new molecular understanding of solids, liquids, and vapor pressure. The chapters in this book are papers that we wrote to explain osmosis.
 
It has certainly been an interesting task. We are thankful to the many that have provided support during this process. Some of these are: Dr McGuay, Dr Kenny and Mr Sandstorm (Bradley University), and Dr WL Chow and Mr Hebrank (University of Illinois). We owe thanks to all whose direct or indirect efforts put us in position to look at the osmosis phenomena including Jeff Elwer (DeKalb Genetics), to family and friends especially my children Lori, David, Kathleen & their families. Grateful thanks to Jim Niewold, Dee Diehl, Denny O’Hara,Dick Moudy, Sandy Talley and Ella Benzinger who brought support at special times during and through this process.
Osmosis
J.A. Nollet discovered osmosis in 1748. He experimented with water, wine, and a membrane from a pig’s bladder. Instead of the wine filtering downwards through the membrane into the water, the water flowed upwards into the wine. This was overwhelming and has eluded solution for more than 250 years.
 
We present the complete solution for osmosis. It includes an improved molecular model for solids, liquids, and vapor pressure.
 
This allows a completely new view of Osmosis, diffusion, and molecular behavior of substances. Its applications include chemistry, biology, medicine, physics, diffusion and more.
 
It explains how a single molecule passes through a membrane. It provides the key to:
• Designing a medicine for diseased cells.
• Understanding the collection of maple syrup
• Producing low cost pure water
• Understanding anatomy and much more!
Chapter 1
Seed Storage Defined: Temperature, Relative Humidity and Vapor Pressure.
Abstract
Equilibration curves are well-known data sets used for defining acceptable seed storage conditions. The data relates properties of the seed to acceptable atmospheres for storing seeds in air. It represents the combined property of seeds and air. Thermodynamic properties of air are readily available as psychrometric charts and tables.
 
We propose a new seed characteristic by combining the equilibration data with the properties of air. The proposed seed characteristic is unique to the seed and is presented in graphical form. It relates seed temperature, moisture content, and vapor pressure.
 
We apply this seed characteristic to hermetic storage. Our model confirms the experimental results that seeds stored in hermetic containers maintain constant moisture content.
We also use the seed characteristic to identify some limiting conditions for viable short and long-term seed storage.
Introduction
Maintaining seed viability during storage is important for commercial seed companies as well as research stations. Treated seed with low germination percentage must be disposed of as waste material and replenished by planting and harvesting. Models for predicting seed viability as a function of storage conditions are important tools for making economic decisions regarding storage methods.
 
Several researchers have developed models and guidelines to predict seed viability loss in terms of storage conditions (Roberts, 1973, Ellis & Roberts, 1980, Walters, Kameswara, & Xiaorong, 1998, Mead & Gray, 1999) Experimental data for seed viability is correlated against initial seed water content and storage temperature. Seeds are currently stored in controlled temperature and relative humidity environments or in moisture impervious bags at controlled temperature. Experimental measurements of seed viability are correlated to the initial and storage conditions.
 
Before long-term storage, seeds are dried or humidified to establish specific seed water content. One process used to establish initial values for seed water content is equilibrating seeds in a controlled humidity and temperature environment. Data from these tests has been termed water sorption isotherm curves.
 
Water sorption isotherm data is reexamined in this paper by introducing a new variable, moisture vapor pressure. At given temperature and relative humidity, moisture vapor pressure is a characteristic of moist air that can be readily calculated from empirical equations. We postulate that at equilibrium conditions, the moisture vapor pressure in the seed is equal to the moisture vapor pressure in the equilibrating moist air environment. Furthermore, we propose that the calculated value of the seed moisture vapor pressure is a characteristic property of the seed at the specified equilibrating moisture content and temperature.
Seed Data
Seeds equilibrated under conditions of constant temperature and relative humidity will approach a certain and repeatable value for temperature and moisture content.
 
Although many factors may be important in maintaining seed vitality during short and long-term storage, we limit this discussion to seed temperature and moisture content. Furthermore, we consider only constant temperature and constant seed moisture content during short or long-term storage.
 

 
At equilibrium, there will be no heat or moisture exchange between a seed and its environment. The temperature of the seed will equal the temperature of the environment and the moisture content of the seed will be in balance with the moisture content of the environment.
 
Equilibration data for yellow dent corn is shown in figure 2. The graph shows storage conditions that will maintain constant seed moisture content.
 
From figure 2, for seed at 15% moisture content, equivalent storage atmospheres are:
 
32 °F, 49% relative humidity;
70 °F, 62% relative humidity;
And 90 °F, 68% relative humidity.
At each of these storage atmosphere conditions the seed moisture content will remain constant at 15%. The seed vitality then becomes only a function of the storage temperature. We note that all of this seed storage information is directly available from the seed equilibration curves.
 

The equilibration curves were generated with the modified Henderson equation:
 

Where: Mc = moisture content dry weight %; rh = relative humidity %; T=temperature ºC (ºC = (ºF-32)/1.8)
And, the empirical constants for yellow dent corn are:
 
K=8.6541x10-5; N = 1.8634; C = 49.810.
 
The equilibration curve, figure 2, is actually a combination of the properties of the seed and the properties of atmosphere where the seed is stored.
Thermodynamics of Moist Air
The psychrometric chart, figure 3, displays some of the thermodynamic properties of moist air.
 
Thermodynamics relates to energy and its transformations. When a sufficient number of thermodynamic properties of a substance are known, a unique value for the remaining properties can be determined. Thermodynamic properties are directly related to the energy of a substance or a system. Thermodynamic properties of standard air are presented in tables and on psychrometric charts as shown in Figure 3.
 
In many fields, thermodynamic properties of temperature, pressure, and relative humidity are considered independent thermodynamic variables because they can be directly measured using common instruments. Some commonly used dependent thermodynamic variables are chemical potential, Gibbs free energy, enthalpy, entropy, and vapor pressure.
 
For an ideal gas, the thermodynamic prop