Norashikin Ahmad Zamanhuri

Removal of methylene blue from aqueous solution by adsorption onto NaOH-treated rambutan peel

Adsorption of methylene blue (MB) by NaOH-treated rambutan peel (N-RP) was examined. The adsorption experiments were carried out under different conditions of initial concentration (25-500 mg/L), solution pH 2-12 and N-RP dose (0.05-1.0 g). The influence of these parameters on the adsorption capacity was studied using the batch process. MB adsorption uptake was found to increase with increase in initial concentration and contact time. The MB adsorption was unfavourable at pH<;4. Langmuir, Freundlich and Temkin isotherm models were used to illustrate the experimental isotherms and isotherms constant. The equilibrium data were best represented by Langmuir isothem model, showing maximum monolayer adsorption capacity of 231.34 mg/g. The rates of adsorption were found to obey the rules of pseudo-second order model with good correlation. The result suggested that the N-RP would be an excellent alternative for the removal of MB by adsorption process.

Adsorption of reactive dye Remazol Brilliant Blue R from aqueous solutions by rambutan peel

Adsorption of Remazol Brilliant Blue R (RBBR) by rambutan peel (RP) was examined. The adsorption experiments were carried out under different conditions of initial concentration (25-500 mg/L), solution pH 2-12 and RP dose (0.05-1.2 g). The influence of these parameters on the adsorption capacity was studied using the batch process. RBBR adsorption uptake was found to increase with increase in initial concentration and contact time. The RBBR adsorption was favourable at pH<;4. Langmuir, Freundlich and Temkin isotherm models were used to illustrate the experimental isotherms and isotherms constant. The equilibrium data were best represented by Langmuir isotherm model, showing maximum monolayer adsorption capacity of 112.69 mg/g. The rates of adsorption were found to obey the rules of pseudo-second order model with good correlation. The results suggested that RP has high potential to be used as effective adsorbent for RBBR removal.

Green biosynthesis of nanosilvers using aqueous extract from Orthosiphon stamineus leaves

Plant based biosynthesis of nanoparticles is a green chemistry methodology that has been claimed as a simple, cost effective and environmental friendly process, alternatively to the conventional methods (chemical and physical). Nanosilver (NS) synthesis by a biological route using Orthosiphon stamineus aqueous leaf extracts has been studied. The NSs were characterized using UV-vis spectroscopy, transmission electron microscopy (TEM) attached with scanning TEM (STEM) and energy-dispersive X-ray spectroscopy (EDX). NSs were formed when the colour of the liquid reaction changed from clear to brownish-yellow. The formation of the NS was confirmed by UV-vis spectroscopy analysis which the result of the spectra and absorbance peaks at 432 nm. TEM analysis revealed that NS formed has crystalline nature with spherical shape and the particle size was ranging from 2 to 47 nm. The presence of silver was confirmed by EDX analysis with the aid of STEM.

Green synthesis and characterizations of silver and gold nanoparticles using pink guava waste extract (PGWE)

Metal nanostructures have unusual physicochemical properties and biological activities compared to their bulk parent materials. Thus in recent years a number of physical, chemical and biological techniques were applied for the development of metal nanoparticles (NP). In this paper we have reported the green synthesis of silver (AgNPs) and gold (AuNPs) nanoparticles by reduction of silver nitrate and chloroauric acid solutions, respectively, using fruit extract of pink guava waste. Surface plasmon resonance spectra for silver and gold are obtained at 451 and 578 nm with brown yellow and pink-red color, respectively. Silver and gold nanoparticles vary in size according to different temperature and aging time used for the synthesis. The instrumental techniques were applied to characterize the synthesized silver and gold nanoparticles is UV-vis.

Biosynthesis of silver nanoparticles using pink guava waste extract (PGWE)

Bio-inspired silver nanoparticles were synthesized with the aid of a novel, non-toxic, eco-friendly biological material namely, pink guava waste extract (PGWE). The pink guava waste extract will act as the reducing agent in reduction process in order to reduce the aqueous salt solutions of the silver nitrate. Moreover, economically, this process will also lower the cost of producing metal nanoparticles compared to other methods. Boiled, separated, filtrated process was used for reducing silver nitrate. Silver nanoparticles were formed when the reaction conditions were altered with respect to ratio of extraction, pink guava waste extract content and aging time. The nanoparticles were characterized by UV-vis spectroscopy, Fourier Transform Infrared (FTIR) Spectroscopy and Transmission Electron Microscope (TEM). The colorless reaction mixtures turned brown and displayed UV - visible spectra characteristic of silver nanoparticles. Fourier transform infrared spectroscopy (FTIR) indicated the role of different functional groups (carboxyl, amine and hydroxyl) in the synthetic process. After 72 h of treatment, silver nanoparticles obtained were in the range of 23-105 nm as obtained from TEM.