Biodegradation of phenol in batch and continuous flow microbial fuel cells with rod and granular graphite electrodes

<p>Phenol biodegradation was evaluated in batch and continuous flow microbial fuel cells (MFCs). In batch-operated MFCs, biodegradation of 100–1000 mg L⁻¹ phenol was four to six times faster when graphite granules were used instead of rods (3.5–4.8 mg L⁻¹ h⁻¹ vs 0.5–0.9 mg L⁻¹ h⁻¹). Similarly maximum phenol biodegradation rates in continuous MFCs with granular and single-rod electrodes were 11.5 and 0.8 mg L⁻¹ h⁻¹, respectively. This superior performance was also evident in terms of electrochemical outputs, whereby continuous flow MFCs with granular graphite electrodes achieved maximum current and power densities (3444.4 mA m⁻³ and 777.8 mW m⁻³) that were markedly higher than those with single-rod electrodes (37.3 mA m⁻³ and 0.8 mW m⁻³). Addition of neutral red enhanced the electrochemical outputs to 5714.3 mA m⁻³ and 1428.6 mW m⁻³. Using the data generated in the continuous flow MFC, biokinetic parameters including <i>μ</i>_m, <i>K</i>_S, <i>Y</i> and <i>K</i>_e were determined as 0.03 h⁻¹, 24.2 mg L⁻¹, 0.25 mg cell (mg phenol)⁻¹ and 3.7 × 10⁻⁴ h⁻¹, respectively. Access to detailed kinetic information generated in MFC environmental conditions is critical in the design, operation and control of large-scale treatment systems utilizing MFC technology.</p

Summary of peer-reviewed literature on consumer preference for e-cigarette attributes.

<p>Summary of peer-reviewed literature on consumer preference for e-cigarette attributes.</p

A summary of preference for e-cigarette flavors.

<p>A summary of preference for e-cigarette flavors.</p

A systematic review of consumer preference for e-cigarette attributes: Flavor, nicotine strength, and type

<div><p>Objective</p><p>Systematic review of research examining consumer preference for the main electronic cigarette (e-cigarette) attributes namely flavor, nicotine strength, and type.</p><p>Method</p><p>A systematic search of peer-reviewed articles resulted in a pool of 12,933 articles. We included only articles that meet all the selection criteria: (1) peer-reviewed, (2) written in English, and (3) addressed consumer preference for one or more of the e-cigarette attributes including flavor, strength, and type.</p><p>Results</p><p>66 articles met the inclusion criteria for this review. Consumers preferred flavored e-cigarettes, and such preference varied with age groups and smoking status. We also found that several flavors were associated with decreased harm perception while tobacco flavor was associated with increased harm perception. In addition, some flavor chemicals and sweeteners used in e-cigarettes could be of toxicological concern. Finally, consumer preference for nicotine strength and types depended on smoking status, e-cigarette use history, and gender.</p><p>Conclusion</p><p>Adolescents could consider flavor the most important factor trying e-cigarettes and were more likely to initiate vaping through flavored e-cigarettes. Young adults overall preferred sweet, menthol, and cherry flavors, while non-smokers in particular preferred coffee and menthol flavors. Adults in general also preferred sweet flavors (though smokers like tobacco flavor the most) and disliked flavors that elicit bitterness or harshness. In terms of whether flavored e-cigarettes assisted quitting smoking, we found inconclusive evidence. E-cigarette users likely initiated use with a cigarette like product and transitioned to an advanced system with more features. Non-smokers and inexperienced e-cigarettes users tended to prefer no nicotine or low nicotine e-cigarettes while smokers and experienced e-cigarettes users preferred medium and high nicotine e-cigarettes. Weak evidence exists regarding a positive interaction between menthol flavor and nicotine strength.</p></div