Functionalized hydrogels for controlled crop nutrient release

Feeding our growing world population, currently estimated to be increasing by just over 1% per annum, is a significant and ever more prescient global challenge. Many countries face enormous problems in being able to manage staple crop production with suitable farming practise. Of these key problems, water, nutrient and crop-protection strategies are amongst the most important to address. These are, in turn, most pressing in countries such as India, which is home to 15% of the worlds undernourished population. In order to explore new method of addressing such problems, we will here focus on local, systemic mechanism for managing water retention, nutrient and protection release for staple crops by the use of modified hydrogel composites (MHCs). Whilst there is a rich literature within this field, our approach is novel as it explores the simultaneous release of multiple key nutrients within a local and controlled environment.<br /> <br /> The overall aim of this project is to: develop hydrogel systems based on both inorganic and organic gelators, with the capability of promoting the controlled release of multiple nutrient sources (particularly nitrates, phosphates). In order to achieve this overall aim, the project is divided into a suite of work-packages (WP) each of which has key deliverables. These together will address the overall aim of the project. Methodology includes Selection of gelator systems to explore, Chemical Functionalisation of Organic Gelators Organic hydrogel systems, Functionalisation of Inorganic Mineral Gelators, Examination of Nutrient Release Kinetics Phosphate and Examination of Environment-Responsive Nutrient Release Kinetics.

<p><strong>Methodology</strong></p> <h4>Selection of gelator systems to explore</h4> <p>We will examine various different gelator systems for producing hydrogels. Our investigations will include work on organic gelators, especially those that are recognised as being naturally occurring and low toxicity hydrogelators such as guar and gallan gum.</p> <p>We will also examine mineral or inorganic gelators including silica hydrogels and hydrogel; based on the synthetic clay mineral laponite.</p> <p>Deliverables: Reasoned selection of hydrogel systems to be explored.</p> <h4>Chemical Functionalisation of Organic Gelators Organic hydrogel systems</h4> <p>These systems, based on guar or gellan gum, have the potential to be covalently modified at the hydroxyl functionalities. We will examine mechanisms to do this by a combination of phosphorylation and hydrolysis to afford terminal phosphate functions. Phosphorylation will be performed using known phosphorylating agents such as amido and/or diamidophosphates.</p> <p>Preparation and characterisation of functionalised organic hydrogel systems.</p> <h4>Functionalisation of Inorganic Mineral Gelators</h4> <p>The key aspects of functionalisation with the context of the mineral, inorganic gels such as laponites is to exploit the natural electrostatic interactions between clay particles to encapsulate phosphate and nitrate salts between the stacked clay particles. In addition, we will explore the ability of surfactant additives (such as sodium dodecyl sulfate) on stabilising such salts with the hydrogel environment.</p> <p>Deliverables: Preparation and characterisation of functionalised mineral hydrogel systems.</p> <h4>Examination of Nutrient Release Kinetics Phosphate</h4> <p>Release kinetics will be examined in a controlled reactor space, both using static water sinks and dynamic watercourses. Analytical determination of phosphate will be achieved using a combination of quantitative 31P-NMR spectroscopy and also by fluorescent tagging of phosphate; both techniques having sensitivities in the sub-ppm range. Deliverables: Scope of phosphate and nitrate release kinetics as a function of environmental and hydrogel properties.</p> <h4>Examination of Environment-Responsive Nutrient Release Kinetics</h4> <p>In this work-package, we note the unusual behaviour of laponite clays, where the gel properties change over time as the clay particles organise themselves. We will examine how it may be possible to control the structure/viscosity of the hydrogel by local environmental conditions such as physicochemical changes in pH or presence of chemicals released by a second, composite hydrogel (a guar gel for example). Deliverables: Potential for using remote, environmental triggers for nutrient release from hydrogel systems.</p> <h3>References</h3> <p>1. J. Saltiel, J. W. Bauder, S. Palakovich. Adoption of Sustainable Agricultural Practices: Diffusion, Farm Structure, and Profitability. Rural Sociology (1994), 59, 333-349.</p> <p>2. I. P. Abrol and Sunita Sangar. Sustaining Indian agriculture – conservation agriculture the way forward. Current Science (2006) 91, 1020-1025.</p> <p>3. <a href="http://https//scroll.in/bulletins/73/how-sustainable-farming-in-india-can-secure-its-food-for-the-future">How sustainable farming in India can secure its food for ther future.</a></p> <p>4. M. Cassanelli, I. Norton, T. Mills. Role of gellan gum microstructure in freeze drying and rehydration mechanisms. Food Hydrocolloids (2018) 75, 51-61.</p> <p>5. Ruzicka B. et al. Observation of empty liquids and equilibrium gels in a colloidal clay. Nat. Mater. (2011) 10, 56–60.</p> <p>The earliest start date for this project is 1 October 2020.</p>

<p>Formal applications for research degree study should be made online through the <a href="www.leeds.ac.uk/info/130206/applying/91/applying_for_research_degrees">University's website</a>. Please state clearly in the Planned Course of Study section that you are applying for <em><strong>PHD Chemistry FT, </strong></em>in the research information section that the research degree you wish to be considered for is <strong><em>F</em></strong><em><strong>unctionalized hydrogels for controlled crop nutrient release</strong></em> as well as <a href="https://physicalsciences.leeds.ac.uk/staff/177/dr-terence-kee">Dr Terence Kee</a> as your proposed supervisor and in the finance section, please state clearly <em><strong>the funding that you are applying for, if you are self-funding or externally sponsored</strong></em>.</p> <p>If English is not your first language, you must provide evidence that you meet the University's minimum English language requirements (below).</p> <p style="margin-bottom:11px"><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p> <p class="MsoNoSpacing">Applications will be considered on an ongoing basis.  Potential applicants are strongly encouraged to contact the supervisors for an informal discussion before making a formal application.  We also advise that you apply at the earliest opportunity as the application and selection process may close early, should we receive a sufficient number of applications or that a suitable candidate is appointed.</p> <p style="margin-bottom:11px"><strong>Please note that you must provide the following documents in support of your application by the closing date of Monday 6 January 2025 if applying for the China Scholarship Council-University of Leeds Scholarship, Monday 3 February 2025 if applying for Leeds Doctoral Scholarship or Tuesday 1 April 2025 for Leeds Opportunity Research Scholarship.</strong></p> <p>If you are applying with external sponsorship or you are funding your own study, please ensure you provide your supporting documents at the point you submit your application:</p> <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date</li> <li>Personal Statement outlining your interest in the project</li> <li>CV</li> </ul>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<p style="margin-bottom:12px"><strong>Self-Funded or externally sponsored students are welcome to apply.</strong></p> <p><strong>UK</strong> – The <a href="https://phd.leeds.ac.uk/funding/138-leeds-doctoral-scholarship-2025-faculty-of-engineering-and-physical-sciences#:~:text=Key%20facts&text=One%20Leeds%20Doctoral%20Scholarship%20is,rata%20for%20part%2Dtime%20study.">Leeds Doctoral Scholarship</a> <strong>(closing date: Monday 3 February 2025)</strong> and <a href="https://phd.leeds.ac.uk/funding/234-leeds-opportunity-research-scholarship-2022">Leeds Opportunity Research Scholarship</a> <strong>(closing date: Tuesday 1 April 2025).</strong> <a href="https://phd.leeds.ac.uk/funding/60-alumni-bursary">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p><strong>Non-UK </strong>–The <a href="https://phd.leeds.ac.uk/funding/48-china-scholarship-council-university-of-leeds-scholarships-2021">China Scholarship Council - University of Leeds Scholarship</a> is available to nationals of China <strong>(closing date: Monday 6 January 2025)</strong>. The <a href="https://phd.leeds.ac.uk/funding/73-leeds-marshall-scholarship">Leeds Marshall Scholarship</a> is available to support US citizens. <a href="https://phd.leeds.ac.uk/funding/60-alumni-bursary">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p>You will be responsible for paying the overtime fee in full in your writing up/overtime year (£320 in Session 2024/25), but the scholarship maintenance allowance will continue to be paid for up to 6 months in the final year of award.</p> <p><strong>Important:</strong> Please note that that the award does <em><strong>not </strong></em>cover the costs associated with moving to the UK.  All such costs (<a href="https://www.leeds.ac.uk/international-visas-immigration/doc/applying-student-visa">visa, Immigration Health Surcharge</a>, flights etc) would have to be met by yourself, or you will need to find an alternative funding source. </p> <p>Please refer to the <a href="https://www.ukcisa.org.uk/">UKCISA</a> website for information regarding Fee Status for Non-UK Nationals.</p>

<p>For further information about your application, please contact PGR Admissions by email to <a href="mailto:maps.pgr.admissions@leeds.ac.uk">maps.pgr.admissions@leeds.ac.uk</a></p> <p>For further information about this project, please contact Dr Terence Kee by email to <a href="mailto:T.P.Kee@leeds.ac.uk">T.P.Kee@leeds.ac.uk</a></p>