Synthesis Of Silver Nanoparticles Using Kyllinga Brevifolia Extract And Immobilisation On Tio2 Nanotubes For Methyl Blue Dye Removal

The textile industry is an intesive producer of wastewater which unless treated may result in the discharged of toxic and harmful dyes to the environment. One method that can be used to remove dyes is by reduction on a surface of catalyst. The catalyst chosen in this work was silver nanoparticles (AgNPs) synthesised by salt reduction technique. The first part of this thesis focused on the synthesis process of AgNPs. However instead of using typical reductant, AgNPs were synthesised by green chemical route utilising Kyllinga brevifolia extract (KBE) as reducing agent. The KBE was also found to be a good capping as well as stabilizing agent. By controlling the temperature, concentration of AgNO3 as the silver precursor, concentration of KBE and reaction time, the AgNPs were sucsessfully synthesised. The phytochemical constituents in KBE responsible for Ag+ reduction were identified. Carbohydrate, protein, plant sterol (stigmasterol and campesterol) were found to have the highest concentration thus proposed as the main constituents that can reduce Ag+ ions to Ago. KBE derived AgNPs are highly dispersed with ~ 17.64 nm diameter and have quasi-spherical shape. The catalytic removal of MB was then done to demonstrate the properties of AgNPs in removing MB. Four (4) systems were used to investigate the performance of AgNPs; System 1 (AgNPs alone), System 2 (AgNPs + NaBH4), System 3 (AgNPs + KBE) and System 4 (AgNPs on TNTs). From the catalytic study on MB removal, no reduction was observed in System 1. Reduction was the highest in System 2. The pseudo first and second order approaches were used for the kinetic study of System 2. 100% removal efficiency (%RE) was found to be possible in 30 ppm MB solution with pH 8-10 which followed first order kinetic with reaction rate of 2.5715 min-1. For 100 pm solution, the first order kinetic was 1.4614 min-1. It took less than 5 mins for the 100% removal which is considered to be extremely fast. On the other hand, for System 3, 93 %RE of MB was achieved with a rate of reaction of 0.2663 min−1 at pH 2. The efficient removal is proposed to be due to the process of reduction occuring via electron relay effect whereas in System 3, sedimentation occurred along with the reduction process. However, at the end of the process it was observed that seperation of AgNPs from the treated MB solution was difficult which may pose a secondary pollution. In order to circumvent this, in the second part of this thesis, System 4 was introduced where AgNPs were immobilised on TiO2 before being subjected to be used as catalyst for MB removal. The TiO2 was fabricated on a surface of titanium wire by anodic process. The anodic film was made to be in a form of TiO2 nanotube (TNT) arrays and AgNPs were then dispersed on the TNTs as catalyst support by wet impregnation technique. The TNTs/AgNPs were characterized and their catalytic activity was tested for removal of MB. However, it was found that the removal efficiency was much slower as compared to when AgNPS were used. The reduction of MB by TNTs/AgNPs followed pseudo-first order kinetic with the kinetic rate of 7.5 x 10-3 min-1

Removal of congo red dye from aqueous solution by bagasse / Norain Isa, Nor Aziyah Bakhari and Jaudat Hamidon

The present study deals with the utilisation of unmodified bagasse (UMB) as an adsorbent for the removal of congo red (CR) from aqueous solutions. The effect of adsorbent dosage, contact time and initial CR concentration on the adsorption are investigated. Then, the optimum conditions are applied to acid-modified bagasse (AMB) and base-modified bagasse (BMB) for comparative study. The maximum CR removal capacity by UMB, BMB and AMB are 6.813, 7.664 and 5.295 mg g⁻¹ respectively. It is found that sufficient time for adsorption equilibrium of CR is 60 min. Equilibrium isotherms for the adsorption of CR on UMB is analysed by the Langmuir and Freudlich isotherm equations. These results can be helpful in designing a batch mode system for the removal of CR from wastewate

Application of bagasse and coir as sorbent dust for heavy metal and dye remediation from aqueous solution / Norain Isa, Nor Aimi Abdul Wahab and Dr. Nor Aziyah Bakhari

Dyes, pigments and heavy metals represent common and dangerous pollutants, originating in large quantities from dye manufacturing, textile as well as pulp and paper industries. They are emitted into wastewaters and produce difficult to treat water contamination, as the colour tends to persist even after the conventional removal processes [1,2]. The conventional techniques used for dyes and heavy metal removals are expensive, have average efficiency and are running in sequential steps. For example, on the commercial scale the ion-exchangers and activated carbons are used, however, with certain disadvantages. The activated carbon is a great adsorbent for dyes but de-sorption and regeneration is difficult under common conditions and the overall process becomes expensive. Moreover, its efficiency in heavy metals removal is average [3,4,5]. Removal of heavy metals and dyes using agricultural waste has been massively investigated due to the abundance of agricultural-related material and its low cost [6,7,8,9]. Various investigated agricultural waste include rice husk ash [10], sunflower stalks [11], sago waste [12] and papaya wood [13]. In this study, bagasse and coir has been choosen as the adsorbent for heavy metal (Cd(ll)) and dyes (methylene and congo red) removal

Chemical constituents of the insecticidal active extract of Tinospora crispa / Nor Aziyah Bakhari, Siti Nur Amirah Diana Fadzillah and Norain Isa

Tinospora crispa Miers (Menispermaceae) is a climbing vine with stems rich in warts. The plant is called Akar Seruntum or Patawali in Malaysia and is widely used for treating skin complaints, malaria, bacterial abscess, high blood pressure and diabetes. In the present study, the stems of T. crispa were collected from the locality and succesively extracted with petroleum ether, followed by chloroform and ethanol. The insecticidal active extract (ethanol extract) was subjected to column chromatography of silica gel eluted with a gradient mobile phase containing hexane, chloroform and ethanol. Among the chemical constituents isolated are n-tetracosyl trans-ferulate and n-octacosyl alcohol, along with three known aporphine alkaloids; N-formylnornuciferine, N-acetylnornuciferine and lysicamine. All compounds were identified by comparing their spectroscopic data (UV, IR, 1H NMR, MS) with data from corresponding values in the literature. Isolation of n-tetracosyl trans-ferulate and n-octacosyl alcohol is reported the first time for T. crispa

A Survey On Medical Digital Imaging Of Endoscopic Gastritis.

This paper focuses on researches related to medical digital imaging of endoscopic gastritis

Gnielinski method in calculating the heat transfer coefficient for metallic solar tower absorber

This work is done to calculate the heat transfer coefficient of metallic wire mesh to air in an open volumetric thermal absorber. It is aimed to replace the actual ceramic with metallic which latter has better thermal properties in order to increase the efficiency of the concentrating solar power plant. The calculation of the heat transfer coefficient from porous wire structure to the air has been conducted to pursue the purpose. The structure that has been chosen is a set of metallic wires with aligned and shifted configurations. The variations of wire diameter together with various porosities from 0.10 to 0.50 have been calculated to obtain the best configuration for the absorber. The flow characteristic within the mesh structure in terms of Reynolds number and its relationship with the heat transfer coefficient has been obtained. The condition on mass flow rate of heat transfer medium and other aspects which influence the heat transfer are also discussed

Controlled release formulation of an anti-depression drug based on a L-phenylalanate-zinc layered hydroxide intercalation compound

The intercalation of L-phenylalanate (LP) into the interlayer gallery of zinc layered hydroxide (ZLH) has been successfully executed using a simple direct reaction method. The synthesised intercalation compound, zinc layered hydroxide-L-phenylalanate (ZLH-LP), was characterised using PXRD, FTIR, CHNS, ICP-OES, TGA/DTG, FESEM and TEM. The PXRD patterns of the intercalation compound demonstrate an intense and symmetrical peak, indicating a well-ordered crystalline layered structure. The appearance of an intercalation peak at a low angle of 2θ with a basal spacing of 16.3 Å, signifies the successful intercalation of the L-phenylalanate anion into the interlayer gallery of the host. The intercalation is also validated by FTIR spectroscopy and CHNS elemental analysis. Thermogravimetric analysis confirms that the ZLH-LP intercalation compound has higher thermal stability than the pristine L-phenylalanine. The observed percentage of L-phenylalanate accumulated release varies in each release media, with 84.5%, 79.8%, 63.8% and 61.8% release in phosphate buffer saline (PBS) solution at pH 4.8, deionised water, PBS solution at pH 7.4 and NaCl solution, respectively. The release behaviour of LP from its intercalation compounds in deionised water and PBS solution at pH 4.8 follows pseudo second order, whereas in NaCl solution and PBS solution at pH 7.4, it follows the parabolic diffusion model. This study shows that the synthesised ZLH-LP intercalation compound can be used for the formation of a new generation of materials for targeted drug release with controlled release properties

Preparation of zinc layered hydroxide–chloroacetate nanohybrid using direct reaction method

The intercalation of chloroacetic acid (CAA) into the interlayer gallery of zinc layered hydroxide has been achieved via a facile direct reaction method. The nanohybrid synthesised, zinc layered hydroxide-chloroacetate was characterised using Powder X-ray diffraction patterns (PXRD), which demonstrated the progressive evolution of the nanohybrid structure, as the CAA molarity were increased from 0.05 to 0.3 M. Sharp and symmetrical peaks of 0.3 M CAA were observed in the PXRD pattern. The emergence of intercalation peak, with basal spacing of 14.3 Å signifying the success intercalation of chloroacetate anions into the interlayer space of the host. The intercalation was also validated by FTIR spectroscopy and CHNS elemental analyser. The increased thermal stability of zinc layered hydroxide-chloroacetate nanohybrid was confirmed by thermogravimetric analysis

Synthesis and Application of Zinc Layered Hydroxide: A Short Review

Zinc Layered hydroxide (ZLH) is a layered material easily synthesized with a structure identical to brucite-like material. Due to the exchangeable anions in the interlayer compensating for the positive charge of a brucite-type layer, ZLH provides a wide application in many fields. This review focuses on the properties and method of synthesis of ZLH by giving an overview of intercalated guest anion in the interlayer of ZLH. The further discussion involved the application of intercalated guest anion in zinc layered hydroxide layer and its properties as a sensitizer, controlled release biomedical, and agriculture to provide the scientific community for research and development by giving current findings. This brief review also presents the success of anion intercalation for controlled release along with the kinetic model involved, which increases the bioavailability and effectiveness of the nanocomposite on its target. It shows the development of research on ZLH nanocomposites toward the sustainability of human life and the environment. This study implies that it is a source of knowledge for researchers about zinc-layered hydroxide materials involving synthesis methods and their application to produce more beneficial nanomaterials

Sensitive and selective detection of chloroform by current-voltage using ZnO nanorods modified electrode

The development of in situ chloroform detection is crucial due to the high risk of carcinogenic effects associated with chloroform exposure. In this study, an electrochemical-based chloroform sensor was fabricated using undoped ZnO nanorods on indium tin oxide (ZnONRs/ITO) electrode to detect chloroform in aqueous-phase samples. Based on the results, the FESEM imaging showed that the ZnONRs exhibited an evenly distributed circular structure with a diameter of 62-90 nm, while the EDX and XRD findings confirmed the presence of Zn and O elements deposited on the electrode surface. Furthermore, the phosphate buffer solution (PBS) solution significantly affected the performance of the modified electrode with an optimal concentration and pH of 0.1 M and pH 7. The results also highlighted the vital function of the modified ZnONRs/ITO electrode as an efficient electron mediator and its catalytic potential to induce chloroform oxidation. Most importantly, the modified ZnONRs/ITO electrode was able to detect the presence of chloroform in real seawater samples, where the repeatability and reproducibility tests achieved a Relative Standard Deviation (RSD) of 1.41% and 2.61%, respectively, indicating the exceptional performance of the modified electrode. Moreover, the modified ZnONRs/ITO electrode recorded a low limit of detection and high sensitivity of 1.50 μM and 2.11 μA/cm2·mM, respectively, within a 0.010-10 mM linear dynamic range. In conclusion, the current-voltage (I-V) method proved the reliable, satisfactory, and effective fabrication of the modified ZnONRs/ITO electrode for chloroform sensing in aqueous-phase samples, including in real seawater samples