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A comparison of kinetic models describing the sorption of pollutants has been reviewed. The rate models evaluated include the Elovich equation, the pseudo-® rst order equation and the pseudo-second order equation. Results show that chemisorption processes could be rate limiting in the sorption step. The pseudo-second order equation may be applied for chemisorption processes with a high degree of correlation in several literature cases where a pseudo-® rst order rate mechanism has been arbitrarily assumed.

Applications of second-order kinetic models to adsorption systems were reviewed. An overview of second-order kinetic expressions is described in this paper based on the solid adsorption capacity. An early empirical second-order equation was applied in the adsorption of gases onto a solid. A similar second-order equation was applied to describe ion exchange reactions. In recent years, a pseudo-second-order rate expression has been widely applied to the adsorption of pollutants from aqueous solutions onto adsorbents. In addition, the earliest rate equation based on the solid adsorption capacity is also presented in detail.

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Objective To estimate ART adherence rates during pregnancy and postpartum in high-, middle- and low-income countries. Design Systematic review and meta-analysis Methods MEDLINE, EMBASE, SCI Web of Science, NLM Gateway and Google scholar databases were searched. We included all studies reporting adherence rates as a primary or secondary outcome among HIV-infected pregnant women. Two independent reviewers extracted data on adherence and study characteristics. A random-effects model was used to pool adherence rates; sensitivity, heterogeneity, and publication bias were assessed. Results Of 72 eligible articles, 51studies involving 20,153 HIV-infected pregnant women were included. Most studies were from United States (n=14, 27%) followed by Kenya (n=6, 12%), South Africa (n=5, 10%), and Zambia (n=5, 10%). The threshold defining good adherence to ART varied across studies (>80%, >90%, >95%, 100%). A pooled analysis of all studies indicated a pooled estimate of 73.5% (95% confidence interval [CI] 69·3–77·5%, I2=97·7%) of pregnant women had adequate (>=80%) ART adherence. The pooled proportion of women with adequate adherence levels was higher during the antepartum (75·7%, 95% CI 71·5–79·7%) than during postpartum (53·0%, 95% 32.8% to 72·7%) (p=0·005). Selected reported barriers for non-adherence included physical, economic and emotional stresses, depression (especially post-delivery), alcohol or drug use, and ART dosing frequency or pill burden. Conclusion Our findings indicate that only 73·5% of pregnant women achieved optimal ART adherence. Reaching adequate ART adherence levels was a challenge in pregnancy, but especially during the postpartum period. Further research to investigate specific barriers and interventions to address them are urgently needed globally.