Evaluating used pencil graphite as an adsorbent for volatile organic compounds (VOCS) | |
| Author | Grace Christine Richardson |
| Call Number | AIT Thesis no.EV-26-03 |
| Subject(s) | Organic compounds--Environmental aspects Graphite--Environmental aspects Pencils--Environmental aspects Waste management |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Pencils are one of the most common school supplies but are often overlooked in waste management, with many discarded into general waste or compost bins and ending up in landfills. The painted coatings, adhesives, and binders in pencils can also release volatile organic compounds (VOCs) that contribute to indoor air pollution in classrooms, while the graphite core itself, despite its potential as an adsorbent material, is rarely recovered or repurposed. Although biochar and graphitic materials have been studied as VOC adsorbents in the broader literature, no published study has specifically evaluated the use of pencil derived graphite as a low-cost adsorbent for indoor VOC control in school environmental. This thesis addresses the gap by characterizing pencil graphite recovered from commercial HB Horse pencils and evaluating its VOC adsorption performance against two commercial reference adsorbents under controlled chamber conditions.The objectives of the study were to (i) compare the VOC adsorption performance of three adsorbents, pencil graphite, high purity natural graphite powder, and activated charcoal with pencil graphite; (ii) characterize the physical and structural properties of the adsorbents to explain the underlying adsorption mechanisms; and (iii) conduct a feasibility study evaluating the cost-effectiveness of pencil graphite based filters for low-cost VOC adsorption applications. Pencil graphite was extracted, washed, dried, and sieved into two adsorbent fractions (20-80 mesh and >80 mesh), and characterized by BET surface area analysis, scanning electron microscopy (SEM), and bulk density measurements. Adsorption performance was tested in a sealed 100 L chamber using whiteboard marker ink as the VOC source, with VOC concentration monitored over a 12-hour analytical period using an ATMO Tube real-time sensor.The pencil graphite was found to be a mesoporous material with a low specific surface area (3.3-5.5 m2 /g, more than 100 times lower than activated charcoal). Standalone pencil graphite achieved only 4-11% VOC removal, compared to 85% for activated charcoal alone and 35% for pure graphite. However, the mixed filter (activated charcoal and >80 mesh pencil graphite blend) achieved 83% VOC removal, statistically indistinguishable from activated charcoal alone (p=0.239-0.915), while using only approximately 13 g of activated charcoal per filter compared to 114 g in the activated charcoal only configuration. Under a hypothetical waste-pencil sourcing scenario, this mixed filter delivered approximately 1.3 times the cost-effectiveness of activated charcoal alone, demonstrating the economic viability of partial activated-charcoal substitution with waste derived pencil graphite. This thesis provides the first experimental evidence that discarded pencil graphite can be incorporated into VOC adsorption filters as a low-cost, upcycled component, supporting circular-economy and zero-waste initiatives in school environments. |
| Year | 2026 |
| Type | Thesis |
| School | Faculty of Civil and Environmental Engineering (2026) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering and Management (EEM) |
| Chairperson(s) | Ekbordin Winijkul |
| Examination Committee(s) | Cruz, Simon Guerrero;Chao, Kuo Chieh |
| Scholarship Donor(s) | Her Majesty the Queen’s Scholarships (Thailand) |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2026 |
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