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    Synthesis of zeolite from industrial wastes: a review on characterization and heavy metal and dye removal
    (Springer, 2024) Eren, Sena; Türk, Feride N.; Arslanoğlu, Hasan
    Increasing world population, urbanization, and industrialization have led to an increase in demand in production and consumption, resulting in an increase in industrial solid wastes and pollutant levels in water. These two main consequences have become global problems. The high Si and Al content of solid wastes suggests that they can be used as raw materials for the synthesis of zeolites. In this context, when the literature studies conducted to obtain synthetic zeolites are evaluated, it is seen that hydrothermal synthesis method is generally used. In order to improve the performance of the hydrothermal synthesis method in terms of energy cost, synthesis time, and even product quality, additional methods such as alkaline fusion, ultrasonic effect, and microwave support have been developed. The zeolites synthesized by different techniques exhibit superior properties such as high surface area and well-defined pore sizes, thermal stability, high cation exchange capacity, high regeneration ability, and catalytic activity. Due to these specific properties, zeolites are recognized as one of the most effective methods for the removal of pollutants. The toxic properties of heavy metals and dyes in water and their carcinogenic effects in long-term exposure pose a serious risk to living organisms. Therefore, they should be treated at specified levels before discharge to the environment. In this review study, processes including different methods developed for the production of zeolites from industrial solid wastes were evaluated. Studies using synthetic zeolites for the removal of high levels of health and environmental risks such as heavy metals and dyes are reviewed. In addition, EPMA, SEM, EDX, FTIR, BET, AFM, and 29Si and 27Al NMR techniques, which are characterization methods of synthetic zeolites, are presented and the cation exchange capacity, thermodynamics of adsorption, effect of temperature, and pH are investigated. It is expected that energy consumption can be reduced by large-scale applications of alternative techniques developed for zeolite synthesis and their introduction into the industry. It is envisaged that zeolites synthesized by utilizing wastes will be effective in obtaining a green technology. The use of synthesized zeolites in a wide variety of applications, especially in environmental problems, holds great promise. Graphical Abstract: (Figure presented.) © The Author(s) 2024.
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    Valorization of waste biomass derived activated carbon @expanded graphite for intensification of thermal characteristics of RT24 phase change material through shape-stabilization
    (Elsevier, 2025) Gowthami, D.; Sharma, R. K.; Kar, Turgay; Sarı, Ahmet; Arslanoğlu, Hasan; Eren, Sena; Gençel, Osman
    The basic philosophy of this work is to create cleaner energy alternative materials for solar thermal energy storage applications. This experimental evaluation focuses on elevating the thermal characteristics of Rubitherm paraffin (RT24) by incorporating a hybrid matrix for shape stabilization. The hybrid matrix was fabricated by infusing expanded graphite (EG) (5 wt% and 10 wt%) into carbonized sugar beet pulp and vinasse wastes (BAC). The shape-stabilization of RT24 was carried out in vacuum to achieve uniform dissipation. The synthesized hybrid supporting matrices were adequately porous with highest BET surface area of 411.25 m2/g after adding EG(5 wt%) to BAC. According to TGA analysis BAC/RT24, BAC@5%EG/RT24(45 %) and BAC@10%EG/RT24 (60 %) were highly resistant to heat with corresponding mass loss of 39.4 %, 44.7 % and 59.8 % at around 280 degrees C. In accordance with XRD and FTIR analysis PCM composites have not displayed structural or chemical transformation due to the presence of EG or BAC. The melting and solidifying latent heat values of BAC@10% EG/RT24(60 %) were measured as 132.15 J/g and 129.42 J/g respectively. Also, BAC/RT24, BAC@5%EG/RT24 (45 %) and BAC@10%EG/RT24(60 %) have revealed high thermal reliability after performing 1000 thermal cycles with a variation of about 3 % in melting latent heat, thus signifying their adaptability into latent heat storage (LHS) systems. Thermal conductivity of the shape-stable BAC/RT24 composite was increased by 300 % compared to pure RT24 PCM as a result of adding 10 wt% EG to the composite. Especially BAC@10%EG/RT24 (60 %) composite can be utilized as cleaner energy alternative material for building solar thermal implementation because it had relatively higher LHS capacity and thermal conductivity value.