Clays are low-price and very useful material for water treatment purpose. In this work, we reported the application of activated natural kaolinite material which obtained from Wediombo beach, Yogyakarta for methylene blue adsorption. The natural kaolinite material was activated under an acidic condition to obtain the activated kaolinite material. The activated kaolinite material was characterized using Fourier transform infrared, X-ray diffraction, scanning electron microscope, and surface analysis. From the adsorption experiment, the activated kaolinite material gave moderate adsorption percentages for methylene blue. The adsorption kinetics followed the Ho and McKay kinetic model while the adsorption isotherm followed Langmuir model. The qmax value for methylene blue adsorption using activated natural kaolinite material was at a moderate level (3.40 mg g-1). The plausible adsorption mechanism of methylene blue on the surface of activated kaolinite material happened through hydrogen bondings and/or electrostatic interactions. These findings are important for a wastewater treatment using a low-cost adsorbent material.

The structural phase transformation in a non-stoichiometric shape memory Fe 42.8 Mn 27.6 Ga 29.6 Heusler glass-coated microwire was experimentally observed using indirect magnetic, permeability, and electrical resistance measurements. While the temperature dependence of magnetization revealed hysteresis of magnetization during the heating and cooling process, magnetic hysteresis loops point to the change in the direction of the easy magnetization axis of the low-and high-temperature phase. Additionally, the unusual behavior of the permeability and electrical resistance measurements are in good agreement with the magnetic measurements. The x-ray diffraction profile measured at room temperature revealed the coexistence of a high-temperature L2 1 phase (a = 5.88 Å) and low-temperature phase with the L1 2 structure (a = 3.71 Å) and can be considered as another proof of the shape memory effect that is expected in the Fe-Mn-Ga-based Heusler alloys. In the presented glass-coated microwire, it is not only possible to shift the transformation temperature with the external magnetic field, but from its initial permeability value, it is possible to determine whether the alloy has undergone the structural transformation. Therefore, the presented Fe-Mn-Ga-based glass-coated microwire may be considered a suitable candidate for microactuators with sensory capabilities.

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