The Potential of Minjingu Phosphate Rock for Water Defluoridation

Joseph Yoeza Naimani Philip ,Francisco Lucas Olambo,J E G Mdoe

doi:10.11648/j.ijsts.20160401.11

Joseph Yoeza Naimani Philip , Francisco Lucas Olambo + Show 1 more

Open Access

https://doi.org/10.11648/j.ijsts.20160401.11

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Abstract

In some parts of Tanzania, fluoride ion concentrations in potable water are higher than recommended by WHO. Consequently, searches for economically and technically viable strategies are required to address this problem. This work aims to determine the potential of phosphate rock mined from Minjingu area in Northern Tanzania as water de-fluoridatant. The results obtained are reported herein. The rock particles were chemically activated and then characterised by XRF, XRD and nitrogen physisorption. Results showed that the main component of chemically activated rock particles was calcium hydroxyapatite with Ca/P ratio of 1.55 whereas the main component of non-activated particles was calcium fluoroapatite (Ca/P ratio of 1.66). The results also indicated that activated rock material was mesoporous with a BET surface area of 57.4 m2/g. Results for water defluoridation showed that the material had a fluoride ion percentage removal of about 90%, when the adsorbent dose was 8 g, contact time of 30 minutes, initial fluoride ion concentration 5 mg/L, pH values of 6.0 to 7.2 and batch volume of 50 mL. The material could be regenerated using 1% NaOH and reused in the water defluoridation process. Therefore, Minjingu Phosphate Rock (MPR) is potential water de-fluoridatant.

Highlights

People obtain water from various sources including rain, surface water and groundwater
The X-Ray Diffractograms of both non-activated MPR (naMPR) and caMPR are shown in Figures 1 and 2
It is clearly seen from this figure that the efficacy of 8 g of caMPR is reduced as the initial fluoride ion concentration is increased

Summary

Introduction

People obtain water from various sources including rain, surface water (lakes, rivers and ponds) and groundwater (boreholes, springs). Fluoride in potable water (water for food preparation and drinking) can either be advantageous or disadvantageous to human health depending on its concentration level. Many people from rural areas in Arusha, Kilimanjaro, Singida and Shinyanga use water with fluoride ions concentrations greater than 1.5 mg/L for drinking and food preparation [6, 7]. It is reported in the literature [8] that fluoride concentrations in groundwater from some parts of Tanzania may be up to 17 mg/L (Shinyanga), 21.3 mg/L (Singida), 32 mg/L (Arusha) and 46 mg/L (Manyara). It was reported elsewhere that 87.4% of children aged between 9 and 13 at Maji ya Chai – Meru, Tanzania were found to have severe dental and skeletal fluorosis [7]

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