Longevity and Recyclability Study of Acid Activated Alkaline Sludge From Photovoltaic Industry Toward Co2 Capture
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Recycling industrial wastage offers an effective strategy to mitigate waste discharge, promoting development of low-cost CO 2 adsorbents aligning with the principles of the circular economy. This study utilized waste alkaline sludge (AS) originated from photovoltaic industry, activated with 1-4M of hydrochloric acid (HCl), to study its effect on CO 2 capture performance. Activated AS were characterized with N 2 adsorption-desorption isotherm (BET-N 2 ), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM-EDX), CO 2 adsorption-desorption isotherm (BET-CO 2 ) and CO 2 temperature programmed desorption (TPD-CO 2 ). AS activated by 2M HCl exhibited highest surface area of 123.73 m 2 /g and dominated by mesopores which played a significant role in CO 2 adsorption. CO 2 capture by physisorption at 25 ºC exhibited adsorption capacity of 0.44 mg/g, which was 20 times increment than. Meanwhile, CO 2 capture performance by chemisorption was 284 mg/g, with temperature ranging from 207–644 ºC and around 9 times higher than inactivated AS. Longevity study revealed that weight loss after prolonged CO 2 exposure for 24 hours remain around 1.4%, indicating adsorption stop after 24 hours. Longer exposure time induce morphological transformation from irregular ellipsoid into packed and aggregated nano coral, thus lessening its adsorption capacity. It was determined that 25 ºC was the optimal temperature for both adsorption and regeneration process. The adsorbent also demonstrated stable recyclability for 5 cycles, showing only 14% capacity reduction at 2nd cycle and achieving a regeneration efficiency of 88.6%.
