Biosorptive Removal of Hexavalent Chromium by Rice Husk Ash and Silica from Aqueous Solution

Hexavalent chromium ion removal by adsorption using rice husk ash and silica prepared from rice husks obtained locally from rice mill as biosorbents was evaluated as low cost wastewater treatment in this study. Batch equilibrium isotherm experiments were performed as well as effect of dosage and initial chromate solution pH to determine the potentials of the sorbent to remove hexavalent chromate ion from synthetic fed wastewater. Equilibrium isotherm experimental data isotherms were tested with isotherm models (Langmuir, Freundlich and Tempkin models), being best represented by the Langmuir model. Optimum conditions were: dosage = 0.5 g / 200 ml at room temperature and pHo > 6. The equilibrium between adsorbate in the solution and on the adsorbent surface was practically achieved in 2 h. The monolayer sorption capacity was 67.45 mg/g for rice husk silica and 55.98 mg/g for rice husk ash. Estimation of energy of the sorption process revealed chemisorption as the prevailing means of interaction between the adsorbents and adsorbates moieties. The abundance and affordable (cheap) cost of rice husks justifies its use as a precursor in the preparation of rice husk ash and silica as effective adsorbents for chromium removal from industrial effluents.Keywords:Hexavalent chromium, Biosorption, Isotherm, Rice husk ash, Rice husk silica DOI: 10.7176/CMR/13-1-02 Publication date: January 31st 202

Maternal and child health interventions in Nigeria: a systematic review of published studies from 1990 to 2014

BACKGROUND: Poor maternal and child health indicators have been reported in Nigeria since the 1990s. Many interventions have been instituted to reverse the trend and ensure that Nigeria is on track to achieve the Millennium Development Goals. This systematic review aims at describing and indirectly measuring the effect of the Maternal, Newborn, and Child Health (MNCH) interventions implemented in Nigeria from 1990 to 2014. METHODS: PubMed and ISI Web of Knowledge were searched from 1990 to April 2014 whereas POPLINE® was searched until 16 February 2015 to identify reports of interventions targeting Maternal, Newborn, and Child Health in Nigeria. Narrative and graphical synthesis was done by integrating the results of extracted studies with trends of maternal mortality ratio (MMR) and under five mortality (U5MR) derived from a joint point regression analysis using Nigeria Demographic and Health Survey data (1990-2013). This was supplemented by document analysis of policies, guidelines and strategies of the Federal Ministry of Health developed for Nigeria during the same period. RESULTS: We identified 66 eligible studies from 2,662 studies. Three interventions were deployed nationwide and the remainder at the regional level. Multiple study designs were employed in the enrolled studies: pre- and post-intervention or quasi-experimental (n = 40; 61%); clinical trials (n = 6;9%); cohort study or longitudinal evaluation (n = 3;5%); process/output/outcome evaluation (n = 17;26%). The national MMR shows a consistent reduction (Annual Percentage Change (APC) = -3.10%, 95% CI: -5.20 to -1.00 %) with marked decrease in the slope observed in the period with a cluster of published studies (2004-2014). Fifteen intervention studies specifically targeting under-five children were published during the 24 years of observation. A statistically insignificant downward trend in the U5MR was observed (APC = -1.25%, 95% CI: -4.70 to 2.40%) coinciding with publication of most of the studies and development of MNCH policies. CONCLUSIONS: The development of MNCH policies, implementation and publication of interventions corresponds with the downward trend of maternal and child mortality in Nigeria. This systematic review has also shown that more MNCH intervention research and publications of findings is required to generate local and relevant evidence