In this study, a precipitation method was employed to prepare a synthetic hydroxyapatite (HAP)/chitosan (CHN) composite by the modification of synthetic HAP with CHN. The HAP/CHN composite was characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). Furthermore, the HAP/CHN composite in a 1:1 ratio (wt.%) was investigated as an adsorbent for the removal of heavy metals ions (such as Cr 6+ , Cd 2+ and Zn 2+ ) from simulated wastewater. Adsorption experiments were conducted in batch mode at room temperature. In addition, the effect of process conditions, such as contact time, was evaluated. Kinetic data were well-described by the pseudo-second-order kinetic model, where adsorption was governed by the intraparticle diffusion model. The HAP/CHN composite demonstrated potential utility as an adsorbent for the removal of heavy metals from an aqueous solution, with the highest maximum adsorption capacities of 39.3, 30.8 and 29.9 mg/g for Cr 6+ , Cd 2+ and Zn 2+ , respectively. The HAP/CHN composite materials with variable structure and composition exhibited remarkably different adsorption properties and potential applicability for industrial applications due to the material cost-effectiveness.
In this paper, the kinetics of photoinduced degradation of rhodamine B (RhB) in aqueous solution utilizing synthesized copper oxide (CuO) particles as catalyst has been studied by measuring the absorbance of the dyes at various time intervals. The CuO particles were fabricated using sol-gel method, and calcined at different temperatures in the range from 450 to 750 °C. The crystallinity of the CuO particles was confirmed using powder X-ray diffraction. The highest RhB degradation efficiency was only 10.9% by the CuO 550 upon UV irradiation in 30 min, proving that CuO particles, regardless of their calcination temperature, showed poor photodegradation activity.
The background of this study began from the problem that Senior High School students in Semarang regency got low score in accounting, the purpose of this study is to explore the competency of accounting teacher and the students' achievement by analysing teachers' competence and the students' achievement for one semester. The result of this research shows that four teachers' competence affected the students' achievement. The education and the training conducted by the teachers also give impact in the relationship of teachers' competence and the students' achievement.
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