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008			201112t20192019my ad||frm||| 000 0 eng d
020			_aTHE0008343(Local) _qhardback
040			_aUMP _beng _cUMP _erda
090			_aFKKSA .S934 2019 r Thesis
100	0		_aNur Syahirah Kamarudin, _eauthor.
245	1	0	_aPreparation of silver nanoparticles in aromatic leaves extract and ionic liquid for photodegradation of 2,4– dichlorophenoxyacetic acid/ _cNur Syahirah Kamarudin
264		1	_aKuantan, Pahang : _bUMP, _c2019
264		4	_c© 2019
300			_axv, 135 pages : _billustrations (some color) ; _c30 cm. + _e1 CD-ROM
336			_atext _2rdacontent
336			_atext _2rdacontent
337			_aunmediated _2rdamedia
337			_acomputer _2rdamedia
338			_avolume _2rdacarrier
338			_acomputer disc _2rdacarrier
347			_atext file _bPDF _2rda
500			_aFaculty of Chemical and Natural Resources Engineering
502			_aThesis (Master of Engineering (Chemical)) -- Universiti Malaysia Pahang – 2019
504			_aIncludes bibliographical references
520	3		_aThe 2,4–dichlorophenoxyacetic acid (2,4–D) herbicide used widely in the agricultural industry is the main toxic pollutant that has caused damage to the aquatic ecosystems and human health. Due to this, continuous research on the effectiveness of catalyst for degradation of this recalcitrant pollutant has been conducted in these recent years. In this study , silver (Ag) catalysts were synthesized and characterized via electrochemical methods in leaves extract and ionic liquid. The performance of the synthesized catalyst towards degradation of 2,4–D was investigated and optimized by Response Surface Methodology (RSM). The kinetic model and reusability of the synthesized photocatalyst were also studied. First, aromatic leaves were extracted using ultrasonic– assisted hydro–distillation (UAE–HD) method and classical aqueous extraction (AE). Then, Ag nanoparticles were synthesized by electrochemical methods with aromatic leaf extracts and ionic liquids as synthesis media. The catalysts were then characterized using X–ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Surface area analysis (BET), UV–vis diffuse reflectance spectra (UV–vis DRS) and Photoluminescence (PL) studies. Then, the photocatalytic activity of the catalyst was tested by degradation of 2,4–D. Furthermore, the optimization of the photocatalytic process was carried out by using Response Surface Methodology (RSM). The kinetic study of the photocatalytic reaction was also analyzed by first order, second order and Langmuir Hinshelwood. Lastly, the reusability study was conducted to determine the efficiency of the catalyst. The results indicated that UAE–HD method was able to yield a higher amount of phenolic content as compared to AE method. The results revealed that ionic liquids and phenolic compounds in leaf extract have synergistic effects to reduce silver ions (Ag + ) into zero–valent Ag nanoparticles and act as capping agents in the nanoparticles formation. Then, the performance of the catalysts was tested towards the photodegradation of 2,4–D in a batch reactor under visible light irradiation. The results showed that the Ag nanoparticles were able to inhibit electron–hole recombination to give a nearly complete degradation (96.54%) of 10 mg L -1 2,4–D at pH 3 when using 0.01 g L -1 of Ag catalyst prepared in 1–butyl–3–methylimidazolium bis(trifluoromethylsulfonyl) imide [BMIM Tf 2 N] ionic liquid and Orthosiphon stamineus (OS) leaves extract media extracted by UAE–HD method. It was found that high amount of phenolic content in leaf extract as well as a long alkyl chain of imidazolium cation and large structure of anion led to diminutive and discrete nanoparticles, which enhanced the photodegradation of 2,4–D. Besides, the existence of the phenolic compound and ionic liquid on the surface of the catalysts play important roles as electron acceptors that enhanced the electron–hole separation process. The response surface methodology (RSM) analysis of the catalysts showed a good significance of model with low probability values (<0.0001) and a high coefficient of determination (R 2 ) with 97.80% of the optimum percentage of 2,4–D degradation at pH 3.24, 0.009 g L -1 of Ag catalyst and 8.15 mg L -1 of 2,4–D concentration. The kinetic studies of the catalysts illustrated that the surface reaction was controlling the step of the process. A reusability study showed that catalysts were still stable after 4 subsequent reactions. Significantly, the synthesis method of the catalysts could be a great advantage in the future development of nanotechnology for degradation of various organic pollutants.
610	2	0	_aFaculty of Chemical and Natural Resources Engineering _xDissertations
650		0	_aUniversities and colleges _xDisertations
650		0	_aTheses
942			_2lcc _cTHESIS