Wide use of dyes in production of fabric becomes the most problematic and generates high amount of liquid effluent pollutants to the surface water. The potential of waste materials, pineapple (Ananas comosus) leaf powder and lime (Citrus aurantifolia) peel powder, to remove Remazol Brilliant Blue R (RBBR) from aqueous solution through adsorption process was investigated. Batch experiments were conducted at initial dye concentration of 500 mg/L. Data analysis showed a removal percentage more than 90 %. The Langmuir, Freundlich, and Temkin isotherm models were also investigated to study the mechanism of dye molecules onto adsorption process. The optimum equilibrium was obtained by the Langmuir isotherm (R ² = 0.9945) for pineapple leaves and (R ² = 0.9994) for lime peel. The maximum monolayer adsorption capacity adsorbents onto RBBR (9.58 mg/g) were achieved. The pseudo-second-order kinetic indicates that the rate constant was 1.00. The specific area of both adsorbents was identified as homogenous structure and was characterized by field emission scanning electron microscopy (FESEM) analysis. The surface functional groups responsible for dye uptake by adsorbents indicate that both adsorbents were defined as carboxyl group which consists of carbonyl and hydroxyl groups and were analyzed by Fourier transform infrared spectrometry (FTIR) analysis. The overall study indicates that adsorbents prepared from pineapple leaves and lime peels are alternative low-cost product in dye removal from aqueous solution.

The aim of this work was to evaluate the antimicrobial activities of leaves and epicarp of Citrus aurantifolia essential oil against Phytophthora colocasiae, the causative agent of taro leaf blight. Oils were extracted by hydrodistillation, and their chemical composition was determined by gas chromatography and gas chromatography coupled with mass spectrometry. Antimicrobial activities of oils were tested in vitro against mycelium growth and sporangium production. In situ tests were done on healthy taro leaves, and the necrosis symptoms were evaluated. Results showed that the essential oil extraction yields from leaves and epicarp were 0.61 and 0.36%, respectively. Limonene (48.96%), bornyl acetate (14.18%), geraniol (10.53%), geranial (3.93%), and myrcene (3.14%) were the main components in leaf oil, while limonene (59.09%), cis-hydrate sabinene (7.53%), geranial (5.61%), myrtenol (5.02%), and terpinen-4-ol (3.48%) were the main components in epicarp oil. Both oils exhibited antimicrobial activities with total inhibition of the mycelium growth at 500 and 900 ppm for leaf and epicarp, respectively. The highest inhibitory concentration of sporangium production was 400 (72.84%) and 800 ppm (80.65%) for leaf and epicarp oil, respectively. For the standard fungicide (metalaxyl), the total inhibition value of mycelial growth and sporangium production was 750 ppm. In situ tests showed that, at 5000 ppm, total inhibition (100%) was obtained for a preventive test, while 50% of the inhibition was observed for a curative test when leaf oil was applied. When epicarp essential oil was applied at 5000 ppm, 47.5 and 16.66% of the reduction of leaf necrosis were observed for the preventive and curative test, respectively. There were positive correlations between both the oil concentration and the reduction of necrosis caused by P. colocasiae. These findings suggest that the C. aurantifolia essential oil could serve as an eco-friendly biocontrol for the management of taro leaf blight.