Surface modified and activated waste bone char for rapid and efficient VOCs adsorption

Current research on volatile organic compound (VOC) removal often focuses on synthetic adsorbents, which can be costly and unsustainable. Prior studies have explored natural materials like bone char, but their adsorption efficiency remains limited. It was already known that bone char, derived from animal waste, has a porous structure suitable for adsorption. However, no prior work had resolved how to enhance its performance for rapid VOC capture. That uncertainty drove the need to investigate surface modification and activation methods for bone char. Researchers have shown that chemical treatments can improve adsorption properties, but the specific effects of phosphoric acid and potassium carbonate on bone char remain unclear. This gap motivated the development of a new approach to functionalize and activate waste bone char. The study aimed to bridge the knowledge between waste utilization and high-performance adsorbent design. By focusing on hierarchical pore structures and surface chemistry, the research sought to advance sustainable VOC removal technologies.

The aim of this study was to develop a high-performance VOC adsorbent from waste bovine bone. The researchers focused on improving the adsorption efficiency and speed of bone char through chemical treatment. They sought to address the limitations of unmodified bone char in capturing volatile organic compounds. The motivation came from the need for sustainable and cost-effective solutions for air purification. The study aimed to explore how surface modification and activation could enhance the adsorption properties of bone char. By using H3PO4 and K2CO3, the researchers intended to modify the pore structure and surface chemistry of the material. The specific problem targeted was the slow adsorption kinetics and limited capacity of untreated bone char. The study aimed to provide a scalable and eco-friendly alternative to commercial adsorbents.

The researchers first pyrolyzed bovine bone at 450°C to produce bone char. They then treated the char with H3PO4 to modify its surface chemistry. Next, they activated the modified char using K2CO3 to create a hierarchical pore structure. The materials were characterized using N2 adsorption isotherms to measure porosity. Scanning electron microscopy (SEM) was used to examine the surface morphology of the samples. Fourier-transform infrared spectroscopy (FT-IR) provided insights into the functional groups on the material's surface. X-ray photoelectron spectroscopy (XPS) was employed to analyze the elemental composition and chemical states. The adsorption performance was tested using static and dynamic toluene adsorption experiments.

The modified and activated bone char showed an ultrahigh total pore volume of 2.807 cm³/g. This hierarchical structure significantly increased the adsorption capacity for VOCs. The specific adsorption capacity reached ∼13.03 mmol/g, which is much higher than previously reported values. H3PO4 modification accelerated the adsorption process, reducing mass transfer resistance. The adsorption behavior was best described by the pseudo-second-order model. The dynamic/static adsorption ratio improved from 70.31% to 78.62% after surface modification. The material retained high efficiency after multiple regeneration cycles. These results suggest that the modified and activated bone char is a promising adsorbent for VOC removal.

The authors concluded that surface modification with H3PO4 and activation with K2CO3 significantly enhanced the adsorption performance of waste bone char. The hierarchical pore structure created by these treatments increased the adsorption capacity and efficiency. The material's high specific adsorption capacity of ∼13.03 mmol/g outperformed existing literature data. The study demonstrated that the modified bone char could rapidly capture VOCs like toluene. The pseudo-second-order model accurately described the adsorption behavior. The improved dynamic/static adsorption ratio indicated better mass transfer properties. The material's regeneration capability suggests potential for repeated use in practical applications. These findings support the use of modified and activated bone char as a sustainable VOC adsorbent.