Photodegradation of Dyes From Cual Batik Waste Using TiO2 Photocatalyst From Ilmenite Bangka

Cual batik is one of the local products of the Bangka Belitung Islands. The expansion of cual batik in Bangka Belitung continues to increase, resulting in an increase in the production of cual batik cloth. Cual batik contains remasol dyes which are carcinogenic so that waste handling is appropriate and safe for the surrounding environment. One of them is using the TiO2 photocatalytic method from ilmenite Bangka. The results of XRF characterization showed that the TiO2 content after magnetic separator and HCl washing reached 69,975% and 77,260%. The results of XRD characterization showed that the optimal temperature of calcination was at 700ºC with the peak diffraction intensity of anatase TiO2 crystals at 2θ 48.9º, 53.53º and 53.92º. In FTIR characterization, there is a functional group spectrum of titanium dioxide (TiO2) at the absorption wave number 795 cm-1 showing Ti-O-Ti stretching vibrations, at wavenumber 2326 cm-1 showing Ti-O stretching vibrations. The results of photodegradation of cual batik waste showed a decrease in the dye content of remazol briliant blue when exposed to UV lamps and sunlight at contact times of 30, 60, and 90 minutes 85.21%, 82,75%, and 86,72% (UV light); 70,75%, 78,92%, and 93.51% (sunlight).

Functional groups of bio-lubricants from crude catfish oil (Pangasius hypothalamus)

Bio-lubricants have great potential in the production of lubricating in the future. Several studies have developed animal oils as lubricants, which come from a by-product of fish processing. Fish oil extracted from the material and processed into bio-lubricants reached the highest yield of 94%. This research aimed to study the bio-lubricants functional groups. The research steps extracted crude fish oil as raw material, hydrolysis using HCl catalyst, polymerization using benzoyl peroxide, and polyesterification using ethylene glycol. The extraction process used the wet rendering method with a ratio of catfish waste (viscera) to the water of 1:2 (w/v) at 70 °C for 30 minutes. The best bio-lubricants were analyzed for functional groups using an FT-IR instrument with a wave range of 4000-450 cm−1. The results obtained were the absorption wavelength peak of 3472 cm−1, indicating O-H bonds with the sloping peak and the weak bond. The absorption wave peak of 3006-2852 cm−1 indicated a strong C-H bond (alkane). The absorption wave peaks of 1743 cm−1 indicated the presence of a C=O double bond. The adsorption wave peaks at 1465 cm−1 indicated carbon chain bonds between C-C, while the absorption wave peaks at 1115 and 1174 cm−1 indicated C-O bonds. The three spectral indicated that the ester groups formed in bio-lubricants. In the polymerization reaction, there was no absorption wave of 1600-1500 cm−1 which indicated that all C=C groups had been polymerized by benzoyl peroxide. Meanwhile, a sloping absorption wave of 3472 cm−1 was found in the polyesterification reaction due to the weak O-H bond. The analysis obtained above showed the differences in wave peak between bio-lubricant and crude fish oil as raw material but had the same group shape.

A 3D Numerical Wave Tank for Coastal Engineering Studies

This paper presents the validation of active and passive, made by a dissipation beach, numerical absorbing methods implemented in RANS-VOF FLUENT® code for modelling long time series of wave propagation interacting with coastal structures. Verification of both numerical techniques was performed in 2D – wave flume, and 3D – wave tank, this one using a multiple active absorption wave makers. The active absorption wave maker allows maintaining the incident wave generation and the mean water level along the time. Good results were obtained for 2D and 3D applications for active absorption wave maker at the generation boundary and both numerical beach and active absorption at the end of the flume/tank.

Perhitungan Energi Disosiasi Gugus Fungsi OH- dan PO43- Hidroksiapatit dengan Pemodelan Spektroskopi Inframerah Berbasis Particle Swarm Optimization (PSO)

<span>Hydroxyapatite Ca<span>10<span>(PO<span>4<span>)<span>6<span>(OH)<span>2 <span>is a calcium phosphate compound having biocompatibility <span>properties. FTIR (Fourier Transform Infrared Spectroscopy) was used to determine the <span>characteristics of the hydroxyapatite group. Modeling the functional groups of hydroxyapatite <span>can be used to obtain vibrational frequencies and spring constants. Analysis of energy release <span>function is performed by calculating the dissociation energy. In this paper will be shown the <span>results of theoretical modeling of hydroxyl and phosphate using spring models. Modeling the <span>functional groups OH<span>- <span>obtained spring constant 524,4559 N/m and the absorption wave number <span>3497,5677 cm<span>-1<span>. Modelling functional groups PO<span>43-<span>obtained spring constant 612,2704 N/m <span>and the wave number 1085,2559 cm<span>-1 <span>absorption. The constant and absorption wave numbers <span>obtained are used to calculate the dissociation energy. OH<span>- <span>dissociation energy obtained by <span>566,5637 kJ/mol and the dissociation energy of PO<span>43- <span>is 567,6248 kJ/mol. Absorption wave <span>numbers are obtained in accordance with experimental results on sometrik stretch modes, and <span>the dissociation energy derived functional group is also close to the value of literature.</span></span></span></span></span></span></span></span></span></span></span></span><br /></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

Theoretical analysis of terahertz generation in periodically inverted nonlinear crystals based on cascaded difference frequency generation process

The characteristics of terahertz (THz) generation based on cascaded difference frequency generation (DFG) process in periodically inverted gallium arsenide ( GaAs ) and gallium phosphide ( GaP ) is calculated from coupled wave equations, in which the output enhancement factors are 5.4 and 3.9 in the two crystals, respectively, compared with DFG without cascading. The optimal interaction length, influence of crystal absorption, wave vector mismatch and pump intensity are analyzed. A short discussion on wavelength tuning is also given. The calculated optimal operating parameters and conclusions can provide good directions for the experimental design.