INVESTIGATING FOAMING SOLUTIONS GENERATED BY NaOH EXTRACTION OF PLANT MATERIALS by Paul Ronald Hudson A thesis submitted to The University of Birmingham for the degree of Engineering Doctorate (EngD) School of Chemical Engineering University of Birmingham September 2013 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. Abstract Surfactants, often derived from crude oil, are included in laundry detergent formulations to clean oily and greasy stains. However, the level of surfactant included is higher than necessary for effectively cleaning clothes in order that foam is generated, as required by consumers, when products are used. This thesis covers extraction from hay with NaOH to produce foaming solutions. Extraction time, temperature and NaOH concentration were found to have varying levels of influence on the properties of the extract solutions. Models were constructed to describe their effects on the % mass extracted from the hay, as well as extract solution absorbance, viscosity, and contact angle using response surface, experimental design methodology. The hay extract foam was examined along with other types of foaming solutions, using cryogenic SEM. Hay, rice straw and horse chestnut leaf extract foams were found to be particle stabilised and interesting images were captured showing their microstructures. Foaming was found to be due to lignin-carbohydrate complexes in hay extract solutions and proteins in horse chestnut leaf extract solutions. Finally correlations were sought between foaming of hay extract solutions and their other properties, e.g. Foaming of the hay solutions is due to lignin derivatives, hence solution absorbance correlates positively with foaming; and foaming is improved by increased solution viscosity hence its positive correlation with solution viscosity and % mass extracted from hay. This thesis is dedicated to my fantastic parents, my brothers, my beautiful daughter Lillian and my wonderful wife-to-be Jenny. Without your love, support and understanding this thesis would not have been possible. Thank you all. “This too shall pass” - Unknown Acknowledgements I would like to thank my supervisors who have all helped me greatly during the course of my EngD. Professors Jon Preece and Zhibing Zhang have helped me to academically appraise and interpret my research then form a viable thesis. Whilst working within P&G the expertise, encouragement and supervision of Nigel Sommerville-Roberts and Alan Brooker helped me to work hard within the project and always strive to increase knowledge and understanding. I am also very grateful to Dr. Richard Greenwood for the input he gave many times during my EngD, and for his handling of the administrative side of the project. On a personal note, every one of those listed above has been incredibly supportive throughout the time I worked on the project and I feel fortunate to have had such a great group of people to work with. Their expertise and knowledge has been invaluable but it is the encouragement they gave that allowed me the confidence to reach the end of my EngD, and this is something I shall always remember. Others at P&G who I would like to thank are Nicola Tilt for her assistance in analysing and interpreting my data and Julian Martin for allowing me to work in his lab (for far longer than originally intended). I also acknowledge the support of P&G and EPSRC. Paul Stanley and Theresa Morris from the University of Birmingham’s Centre for Electron Microscopy, were very helpful in capturing the SEM images in this thesis and I thank them also. Finally I would like to thank my family and friends, especially my parents for their support throughout my education as well as my beautiful daughter Lillian and my wonderful fiancée Jenny. Without you all I would not have made it this far and I am lucky to have you all in my life. Contents List of Figures .................................................................................................................... i List of Tables ................................................................................................................. viii Acronyms and nomenclature ............................................................................................ x Chapter 1 – Introduction................................................................................................. 11 1.1 Project backdrop ................................................................................................... 11 1.2 The 12 Principles of Green Chemistry and Engineering ........................................ 12 1.3 Improving the ‘greenness’ of FMCGs .................................................................... 14 1.4 Palm oil based surfactants .................................................................................... 15 1.5 Biomass ................................................................................................................. 18 1.6 Laundry detergent formulations ........................................................................... 19 1.6.1 Ingredients and functions ................................................................................... 20 1.7 Surfactants, cleaning and sudsing ......................................................................... 20 1.8 Business drivers and expected benefits ................................................................ 23 1.8.1 Business drivers behind the simple alkali extraction process ............................ 24 1.9 Project objectives/questions ................................................................................. 26 1.10 Requirements for success in the current research ............................................... 28 1.10.1 Alkali extraction of plant raw materials to produce sudsing agents .................. 28 1.10.2 The sudsing mechanism ..................................................................................... 28 1.11 Thesis outline ........................................................................................................ 29 1.11.1 Literature review - Chapter 2 ............................................................................. 29 1.11.2 Materials and methods - Chapter 3 ................................................................... 29 1.11.3 Single variable investigation of alkali hay extract solutions - Chapter 4 ............ 29 1.11.4 Modelling work as a continuation of the single variable work – Chapter 5 ...... 30 1.11.5 Examination of the microstructure of foams - Chapter 6 .................................. 30 1.11.6 Correlating sudsing and other extract solution properties – Chapter 7 ............ 30 1.11.7 Conclusions, reflections and further work - Chapter 8 ...................................... 31 1.12 Publications ........................................................................................................... 31 1.12.1 Conference presentations .................................................................................. 31 1.12.2 Patent ................................................................................................................. 31 2 Chapter 2 – Literature review .................................................................................. 32 2.1 Introduction: Overview of this chapter and its context with respect to this EngD thesis ............................................................................................................................... 32 2.2 The composition of lignocellulosic materials ........................................................ 32 2.3 Plant materials used within the current research ................................................ 33 2.3.1 Hay ...................................................................................................................... 34 2.3.2 Straw ................................................................................................................... 34 2.3.3 Leaves ................................................................................................................. 34 2.4 Pretreatment of lignocellulosic materials ............................................................. 35 2.4.1 Lignin ................................................................................................................... 36 2.4.2 Hemicellulose ..................................................................................................... 43 2.4.3 Lignin-carbohydrate complexes ......................................................................... 45 2.4.4 Cellulose.............................................................................................................. 48 2.4.5 Protein ................................................................................................................ 49 2.5 Foams .................................................................................................................... 51 2.5.1 Foaming solutions from lignin derivatives ........................................................