Search

The dyes of the textile dyeing industry wastewater are harmful to humans and the environment. They should be treated before discharging into the environment. The adsorption using the spherical activated carbon can be effective to reduce the dyes. The spherical activated carbon of 3-7 µm in diameter was successfully prepared from the waste bagasse liquid using the hydrothermal method. The activation of this carbon was carried out using the KOH solution. The optimum pH and contact time were achieved in 2 and 200 min, respectively. Adsorption kinetic for RhB on activated spherical carbon follows the second-order kinetics and its adsorption mechanism follows the Langmuir isotherm. The maximum adsorption capacity of spherical activated carbon to Rhodamine B was achieved in 64.52 mg/g.

This report presented the synthesis of Arumanis mango (Mangifera indica L.) leaf extract with chitosan tripolyphosphate matrix and its antibacterial activity. This research aimed to obtain an ointment formulation from mango leaf extract with chitosan tripolyphosphate matrix, to figure out the characteristics, including the particle morphology, and to determine the optimum formulation and the characterization of the antibacterial ointment. The research showed that extract morphology with chitosan tripolyphosphate was uneven-edge aggregates. Antibacterial tests were conducted on P. acnes and E. coli bacteria. The formula giving the greatest antibacterial activity was further utilized for the ointment preparations and then was characterized for 16 days. Formula C (chitosan and NaTPP 1: 0.0992(%)) gave the most excellent inhibition zone for P. acnes and E. Coli bacteria, at 7.94 mm and 10.02 mm, respectively. The obtained ointment preparation was white color homogeneous semi-solid with protective properties. The spreading power of the ointment was 5.25 – 6.25 cm, with the adhesive power of 1 – 5 seconds and pH of 6.0 – 6.4. The ointment's antibacterial activity was tested against P. acnes and E. coli bacteria using the formation of inhibition zone method. The activity of ointment prepared on day one against P. acnes and E. coli was at 14.03 mm and 14.24 mm, respectively, while the activity on day 16 against P. acnes and E. coli was at 9.33 mm and 9.98 mm, respectively.

The chiral separation of econazole, an antifungal drug with one chiral center has been successfully carried out using the high-performance liquid chromatography (HPLC) method. Enantioresolution of econazole (Rs = 2.29) was achieved using cyclodextrin-based chiral column (Astec Cyclobond, 25 cm × 4.6 mm × 5 μm), mobile phase composition of acetonitrile : water (0.2% HCOOH) (20:80, v/v), and UV detection of 220 nm.The optimized HPLC method has been applied for the quantitative determination of econazole in the pharmaceutical (liquid) sample withpercentage recovery of 100.75 % (RSD = 0,95%; n = 3). The effect of several HPLC parameters on the chiral separation of econazole was also evaluated and the method was successfully validated in terms of linearity, accuracy, precision, and selectivity. The present HPLC method was simple, short analysis time, and high resolution.

The Ag3PO4 photocatalyst has been developed to degrade the organic pollutant due to its highly active responsive under visible light irradiation. The properties of Ag3PO4 may depend on design and preparation. Starting materials and co-precipitation conditions would significantly affect the properties of the product. The controlled defect of this photocatalyst may lead to improve catalytic activity. Here, the unique properties of phosphate deficiency in Ag3PO4 were created using the starting material of KH2PO4 and AgNO3 under a mixed solvent of water and ethanol. AgNO3 solution with the ethanol percentages of 0%, 25%, 50%, 75% and 90% was added to KH2PO4 aqueous solution. The photocatalysts were characterized using XRD, DRS, SEM, and XPS. The changes in morphology can be observed from the tetrahedral to the sphere which has smaller particles. The increased atomic ratio of Ag/P and Ag/O suggests that the silver ion enrichment in Ag3PO4 has been created. The activity of Ag3PO4 for Rhodamine B elimination increased by 4.3 times higher compared to that of the pristine Ag3PO4. The enhanced photocatalytic activity might be caused by the smaller particle size and higher silver ion content on the surface of Ag3PO4.

Ag3PO4 is an excellent photocatalyst under visible light irradiation. However, the low stability due to photo-corrosion is still an obstacle in its application. It is a big challenge to improve stability using synthesis modification. Here, the photocatalyst stability enhancement was successfully prepared by tripolyphosphate. Photocatalyst was prepared by reacting AgNO3 solution with STPP (sodium tripolyphosphate) solution to form a white suspension. The addition of phosphate solution to the white suspension produces yellow Ag3PO4 with a new type of defective photocatalyst. The XPS measurement showed that the increase of STPP concentration significantly decreased the Ag/P atomic ratio, indicating the silver vacancy formation on the surface of Ag3PO4. The photocatalytic reaction formed a metallic Ag with a lower d-space in the cube structure occurred in the silver vacancy of Ag3PO4. This defect increases the interaction of metallic silver and Ag3PO4. The enhanced photo-stability might be induced by metallic silver that can act as a photogenerated electron acceptor.

The defect and metallic silver (Ag) in silver phosphate (Ag3PO4) photocatalyst were successfully generated using hydroxyapatite (HA) and glucose. Two steps of synthesis were done in these experiments. Firstly, the Ag/HA powder was prepared by reacting AgNO3 and HA, followed by the addition of a glucose solution. Secondly, the suspension of Ag/HA was reacted with AgNO3 aqueous solution. The yellow product of Ag/Ag3PO4 photocatalyst was produced. The products were characterized using X-Ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS), Scanning Electron Microscope (SEM), Brunauer–Emmett–Teller (BET) and X-ray Photoelectron Spectroscopy (XPS). The decreased ratio of O/Ag and metallic Ag formation observed by the XPS was detected as the possible defect and Ag-doping in the photocatalyst. The enhanced photocatalytic activity might be caused by the oxygen vacancy and metallic Ag in Ag3PO4 that enables the separation of photo-generated electrons and holes.

Synthesis of Ag3PO4 photocatalyst under the varied concentrations of AgNO3 and Na2HPO4·12H2O as starting material has been successfully synthesized using the co-precipitation method. The concentration of AgNO3 is 0.1; 0.5; 1.0; and 2.0 M, whereas Na2HPO4·12H2O is 0.03; 0.17; 0.33; and 0.67 M, respectively. The co-precipitations were carried out under aqueous solution. As-synthesized photocatalysts were examined to degrade Rhodamine B (RhB) under blue light irradiation. The results showed that varying concentrations of starting materials affect the photocatalytic activities, the intensity ratio of [110]/[200] facet plane, and their bandgap energies of Ag3PO4 photocatalyst. The highest photocatalytic activity of the sample was obtained by synthesized using the 1.0 M of AgNO3 and 0.33 M of Na2HPO4·12H2O (AP-1.0). This is due to the high [110] facet plane and increased absorption along the visible region of AP-1.0 photocatalyst. Therefore, this result could be a consideration for the improvement of Ag3PO4 photocatalyst.

The heavy metals distribution of ex-tin mining ponds were investigated. The time chronosequence was determined at the pond of age < 1 year (Station A), the pond of age 5–10 years (Station B), and the pond of age > 15 years (Station C). The results showed sixteen heavy metals of As, Co, Cu, Cr, Fe, Ga, Hf, Sn, Ta, Te, Th, Mn, Ni, Pb, Zn, and V could be detected in the ponds. The metals such as As, Co, Cu, Ga, Mn, Ni, Pb, Th, and Zn in Station C showed higher concentration compared to the Station A and Station B. The metals such as Cr, Fe, Hf, Sn, Ta, Te, and V in Station A and Station B showed higher concentration compared to the Station C. The positive, negative, and dynamic correlation pattern could be found in distribution of heavy metal to time chronosequence. The concentration of Ta and V showed a positive correlation because their concentration decrease, whereas concentration of As, Cu, Ga, Mn, and Zn showed a negative correlation because their concentration increase along in time chronosequence. The dynamic correlation could be found that concentration of Co, Ni, Pb, Sn, and Th decrease from Station A to Station B and then increase in Station C, whereas concentration of Cr, Fe, Hf, and Te increase from Station A to Station B and then decrease in Station C.

This research is conducted to produce carbons from coconut fibre which approach to activated carbon clause continue with carbon surface modification and the adsorption examination to Cu(II) ions. The research consist of several phase. Carbon making of coconut fibre conducted by carbonization processes at 320-400oC with temperature interval 20oC. Carbon yielded in characterized moisture content, ash content and its adsoprtion to iodium. The carbon surface modification conducted by loaded 2-mercaptobenzotiazol (MBT) on carbon. The adsorpsibility of carbon-MBT tested by influence of contact time, pH, and the isoterm adsorption pattern. The result of the study showed carbonization of coconut fibre which approach the requirement of SII No.0258-89 gained at temperature 320oC. In the present study equilibrium time of 10 minute and pH was found to be optimum for both adsorbent. While type of isothermal adsorption from carban and carbon-MBT adsorbent followed the Langmuir adsorption pattern.

The photoreduction of Cd (II) has been investigated using thin layer catalyst of titanium dioxide and chlorophyll as sensitizer. Thin layer catalyst could be prepared by sol gel method deposited on glass slide. The treatments of experimental are: TiO2 catalyst using chlorophyll without sunlight illumination, TiO2 catalyst using chlorophyll with sunlight illumination and TiO2 catalyst with sunlight illumination. The concentration of Cd (II) in the solution is monitored every 30 minutes until 150 minutes illuminations by atomic absorption spectroscopy. The results showed that concentration of Cd (II) decreased reached to 45,53 % in TiO2 catalyst using chlorophyll with sunlight illumination at pH 5 after 150 minutes illumination and it decreased reached to 34.07% at pH 7 after 120 minutes illumination. Addition the chlorophyll to TiO2 catalyst increased photoreduction activities.

Rice husk used as a raw material to produce the rice husk ash. The purpose of this research were to determine the optimum contact time and maximum pH of congo red adsorption by rice husk ash, to find out the influence of particle size to adsorption The rice husk was washed, then soaked in HCl 3.84 M to remove mineral impurities, and it was dried and heated for four hours at the temperature 6000 C. The yield gained from this research is 23.44%. Optimum contact time started at after five minutes and maximum pH is six for the tree mention particle sizes 50, 100 and 140 mesh. Particle size didn’t give any significant effect to adsorption process with percent decreasing of congo red is 84.97 %, 90.39 %, 89.32 % respectively.