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Title:	Copolymer hydrogels of modified cellulose and seaweed as agricultural soil additive
Authors:	Supeno (P57501)
Supervisor:	Rusli Daik, Prof. Dr.
Keywords:	Colloids Soils -- Additives Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	5-Oct-2018
Description:	Ionic hydrogels of grafted cellulose copolymers, acting as agricultural soil additive, were synthesized by radical polymerization method. The cationic hydrogel was produced by using cellulose macro-initiator (MCC-BiB), methacryloyloxy ethyl trimethyl ammonium chloride (METMA), and ethylene glycol dimethacrylate (EGMA) through atom transfer radical polymerization (ATRP) method, in which MCC-BiB was prepared by an acylation reaction of cellulose (MCC) and 2-bromoisobutyryl bromide in zinc-based ionic liquid, while the anionic hydrogel was yielded by chemical oxidative polymerization using seaweed, sodium methacrylate (SMA), EGMA and potassium persulfate (PPS). The MCC-BiB was characterized by using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and nuclear magnetic resonance spectroscopy (NMR). Degree of substitution (DS) for MCC-BiB was calculated from data of TGA. The cationic and anionic hydrogels were characterized by using FTIR, TGA and field emission scanning electron microscopy (FESEM). Swelling and adsorbent properties were studied by using fertilizer solutions. Results showed that the MCC-BiB was successfully synthesized in zinc-based ionic liquid and the DS value was in the range of 12.4% to 37.9%. The highest swelling of cationic hydrogel in water was 71 g/g, when the experimental conditions were at the molar ratio of (macro-initiator: catalyst: monomer: crosslinker was 1:1:13:0.9), 60 oC and 4 hours and from which the crosslinking composition of hydrogel was 22.41%. The best fertilizer adsorption (per g hydrogel) was (88.61 mg Na3PO4, 66.03 mg KCl, 65.26 mg NaNO3 and 64.66 mg KH2PO4). The best fertilizer desorption was (55.38 % KH2PO4, 53.77 % NaNO3, 53.45 % KCl, 49.39 % Na3PO4). The kinetics and isotherm behaviors of fertilizer adsorption were found to best fit with pseudo second order and Langmuir model which indicate that chemisorption mechanism and monomolecular layer adsorption occurred respectively. Results also showed that the highest swelling of anionic hydrogel was 82 g/g in water, when the experimental conditions were at the molar ratio of (seaweed : initiator : monomer : crosslinker was 1 : 3 : 12 : 1), 80 oC and 6 hours and from which the crosslinking composition of hydrogel was 10.91%. The isotherm data showed that Na3PO4 and KCl solutions were in a good agreement with the Langmuir and Freundlich models respectively, while the KH2PO4 and NaNO3 solutions revealed the negative adsorption. However, it actually absorbed fertilizer solutions during swelling process which was supported by diffusing fertilizer species into water from swollen anionic hydrogel as much as 52.85 and 55.18 mg for KH2PO4 and NaNO3 respectively. The adsorption and desorption of fertilizer solutions for a mixture of cationic and anionic hydrogels were also studied. The results showed that the presence of cationic hydrogel in the mixture can increase the fertilizer adsorptions to some extent. However the net adsorption of KH2PO4 was still negative values for the whole range of equilibrium bulk solutions. The presence of anionic and cationic moieties in the hydrogel could retain fertilizer better than that of each alone. This was demonstrated by its lower fertilizer release into water than that of either cationic or anionic swollen hydrogel alone. Thus the ionic hydrogels were found to have a potential application in a sorption field, for example, as a soil additive in soilless agriculture.,“Certification of Master's/Doctoral Thesis” is not available,Ph.D.
Pages:	172
Call Number:	QD549.S847 2018 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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