Indoor ozone removal and deposition using unactivated solid and liquid coffee.

Managing indoor ozone levels is important because ozone is a hazardous pollutant that has adverse effects on human health. Coffee is a popular daily beverage, and thus, coffee beans and spent coffee grounds are common in many places such as offices, homes, aircraft, cafeterias, and such. The most common material used to remove ozone is activated carbon which can be made from coffee beans or spent coffee grounds with proper activation processes. This paper presents a novel idea: to remove ozone at the level of an indoor environment using unactivated coffee products. This paper examines the ozone removal efficiency and the ozone deposition velocity at 130 ppb ozone for two types of coffee: solid coffee (powder) and liquid coffee (beverage). The activated carbon, the deionized water, and the seawater are also included for comparison and validation purposes. The tests show that the fine coffee powder has a removal efficiency of 58.5% and a deposition velocity of 0.62 cm/s. The liquid coffee has a removal efficiency of 34.4% and a deposition velocity of 0.23 cm/s. The chemical inspections indicate that the oxidation reactions with the carbohydrates in solid coffee and the metal/mineral elements in liquid coffee are responsible for ozone removal. These results have confirmed that ozone removal via coffee is effective, controlling indoor air quality by coffee products is thus becoming possible.

The Effects of Inlet Blockage and Electrical Driving Mode on the Performance of a Needle-Ring Ionic Wind Pump.

The thermal management of microelectronics is important because overheating can lead to various reliability issues. The most common thermal solution used in microelectronics is forced convection, which is usually initiated and sustained by an airflow generator, such as rotary fans. However, traditional rotary fans might not be appropriate for microelectronics due to the space limit. The form factor of an ionic wind pump can be small and, thus, could play a role in the thermal management of microelectronics. This paper presents how the performance of a needle-ring ionic wind pump responds to inlet blockage in different electrical driving modes (direct current), including the flow rate, the corona power, and the energy efficiency. The results show that the performance of small needle-ring ionic wind pumps is sensitive to neither the inlet blockage nor the electrical driving mode, making needle-ring ionic wind pumps a viable option for microelectronics. On the other hand, it is preferable to drive needle-ring ionic wind pumps by a constant current if consistent performance is desired.

Corona discharge characteristics of cylindrical electrodes in a two-stage electrostatic precipitator.

Electrostatic precipitator (ESP) is an electrohydrodynamic-based air filter that charges particles based on corona discharge and collects particles by induced electrostatic forces. Inducing corona discharge requires strong electric fields that, however, bring reliability issues because of oxidation. This paper presents the characteristics of an ESP that uses the cylindrical corona electrodes whose longitudinal axis is perpendicular to the surface of the ground electrode. The characteristics include the current-voltage curve, the surface oxidation of the cylindrical corona electrodes, and the element analysis. The characteristics are presented with respect to the pitch and diameter of the cylindrical corona electrodes. The results show that the characteristics mentioned above can correlate to the electric fields around the cylindrical corona electrodes. Stronger electric field around the cylindrical corona electrode results in higher collection efficiency, more oxidation on the cylindrical corona electrode, and shorter life of the cylindrical corona electrode.

Evaluation of Ozone Removal by Spent Coffee Grounds.

Activated carbon is the most known material used to adsorb ozone. Activating carbonaceous materials by ozonation is commonly used to produce activated carbon, however, requiring sophisticated skills and professional equipment. This paper presents a reversed idea: to adsorb ozone using an unactivated carbonaceous material, coffee. Three powder adsorbents are presented: fresh coffee (unactivated), spent coffee grounds (unactivated), and activated carbon (commercially available). The test is conducted by measuring and comparing the ozone concentration in an ozone-supplied chamber with or without the ozone adsorbent. The results show that, at the specific conditions, the peak ozone concentration is lowered by 38% to 56% when the chamber has the activated carbon. At the same conditions, the peak ozone concentration is lowered by 25% to 43% when the chamber has the coffee powders (either fresh or spent). The elemental analysis demonstrates that the oxygen content after the ozone adsorption increases by 20%, 14.4%, and 34.5% for the fresh coffee, the spent coffee grounds, and the activated carbon, respectively. The characteristic analysis (the Fourier-transform infrared spectroscopy, the thermogravimetric, and the Brunauer-Emmett-Teller) suggests that the unactivated coffee is not porous, however, contains various organic compounds that could react with and consume ozone.