Correlation between Calcium Carbonate Content and Emission Characteristics of Incense

Abstract

In Taiwan and China, calcium carbonate is commonly added as a filler during incense production to lower the cost. This study has found an unexpected benefit for this practice: it reduces particulate emission. Nine types of the popular incense on the local market were chosen for this study. The calcium content in raw material incense was analyzed by inductively coupled plasma atomic emission spectrometry, followed by X-ray diffraction (XRD) spectroscopy. The correlation between the calcium content and emission characteristics of incense was investigated. The calcium content varied from 1.8 to 60 mg/g (incense burned) among those nine different types of incense. Very little calcium (Ͻ1%) was found in natural wood or plants, which is mainly the raw material of incense. Instead, most calcium was artificially added in the form of CaCO 3 during manufacturing. The combustion characteristics, including burning rate, emission factors of particulate, ash, and solid-phase polycyclic aromatic hydrocarbons (SPAHs), varied significantly among the nine types of incense. Incense containing 2% calcium would emit 30% less S-PAHs, compared with those with little (Ͻ0.2%) calcium. More importantly, increasing the calcium content from 0.5 to 5% by adding CaCO 3 reduced the particulate emission from incense by ϳ50%.

Reducing emissions of air pollutants from incense burning with the addition of nanoscale calcium carbonate

“…These results indicate that the addition of nano-CaCO 3 significantly reduces the burning time. For the burning rate, results similar to those obtained in our previous study, which investigated nine types of incense and found that incense with higher nano-CaCO 3 content had higher burning rates, were obtained (Yang et al, 2006). In this study, we controlled the process variations and added accurate amounts of nano-CaCO 3 to help verify the reduction of burning time.…”

“…Dynamic mechanical thermal analysis showed that the addition of nano-CaCO 3 led to an increase in storage modulus and glass transition temperature for both PVC and PVC/Blendex blend (Chen et al, 2004). We investigated nine types of incense and found that incense with higher CaCO 3 content had lower PM and PAH emissions (Yang et al, 2006). Therefore, the incense used in the present study was made in our laboratory.…”

Reducing Air Pollution Emissions from Burning Incense with the Addition of Calcium Carbonate

“…Moreover, CaCO 3 with refractory characteristics in terms of low heat transfer coefficient (0.05 W/mol·k) and high molar heat capacity (81.88 J/mol·K) will prevent air convection and thus raise the burning rate of inflammable substances. Compared with the result conducted by Yang (Yang et al, 2006), the reasons for high burning rate observed in this study included different raw materials, smaller diameter incense (2.2 mm in this study, 2.5-3.0 mm in previous study), incense density changes resulted from incense production (semi-handmade in this study, machine-made in previous study).…”

“…2 (Yang et al, 2006). The air exchange rate (Ach) in a domestic environment in Taiwan ranges from 0.8 to 3.5 Ach in summer and 0.5 to 2.0 Ach in winter (Li and Ro, 2000).…”

“…In our previous study, we investigated nine types of incense and found that incense with higher CaCO 3 content had lower PM and PAH emissions (Yang et al, 2006). However, there were variations in the proportion of bamboo, adhesive and wood flour in incense sticks, the size of powder, and the composition of individual additives due to manufacturing differences.…”