This is a sorption study that focused on the use of mica clay mineral grouped into mica untreated, activated mica at 800 °C, mica impregnated separately with iron and aluminium for defluoridation of water. In this study, characterization of adsorbent was done by using XRF and XRD and quantification of fluoride by using fluoride ion selective electrode. Characterization of adsorbent showed the presence of SiO 2 , CaO, P 2 O 5 , Fe 2 O 3 and Al 2 O 3 in the adsorbent. XRD exhibited higher composition of illite, calcite, quartz and albite. Batch experiments were conducted by using a homogeneous mixture of water having 16 mg/L of fluoride. The removal efficiencies of mica alone, activated mica at 800 °C, mica impregnated with iron and mica impregnated with aluminium were found to be 76.02%, 90.21%, 94.40% and 96.88%, respectively. Activated mica and coalesced mica are better adsorbents than mica alone. The optimized pHs were 7.3, 4.4, 7.5, doses of 10, 9 and 8 g, contact time of 40, 35 and 30 min for activated mica, mica impregnated with iron and mica impregnated with aluminium, respectively. The adsorption process obeyed Freundlich model for mica impregnated with aluminium indicating monolayer mechanism, whereas activated mica and mica impregnated with iron agreed with both Freundlich and Langmuir models indicating both monolayer homogeneous and heterogeneous surface conditions. From the kinetic perspective, the fluoride adsorptive reaction followed the pseudo-second-order model. Therefore, activated and modified mica are alternative adsorbents for defluoridation of water.

The presence of fluoride ions in water poses a significant danger to human health. In Tanzania, where the Rift Valley passes, some people are impaired due to elevated levels of fluoride in water. The purpose of this study was to prepare thermally activated Adansonia digitata fruit pericarp biosorbents at 450, 500, 550, and 600°C for defluoridation. Using the Brunauer-Emmett-Teller analyzer, the surface area and pore diameter were measured. The scanning electron microscope and Fourier transform infrared spectrometry were used to determine morphological features and functional groups of biosorbents. To analyze the effect of pH, adsorbent dose, contact time, and initial concentration, the response surface methodology was applied. Adsorption isotherms, kinetics, and regeneration studies were also conducted. There were considerably wide surface areas of 385.44, 399.27, 445.71, and 447.70 m2/g and pore diameters of 0.3055, 3.0341, 3.0375, and 3.0471 nm for biosorbents activated at 450, 500, 550, and 600°C, respectively. FT-IR spectra indicated the oxidation of alcoholic –OH to carboxylic –OH during the activation process, which is proved by the shifting of the peak at 3500-3000 cm-1 from raw biosorbent to a very broad and strong band at 3500-2000 cm-1 from the activated biosorbent. The maximum removal efficiencies of biosorbents activated at 450, 500, 550, and 600°C were 95.55, 96.50, 97.65, and 98.36%, respectively, for all biosorbents at a pH of 2, an initial concentration of 27.50 ppm, a contact period of 75.00 minutes, and an adsorbent dose of 5.50 g, which indicates that the adsorbents were successful for fluoride removal. The isotherms and kinetics indicated that the adsorption fitted well with Freundlich ( R 2 = 0.95661 ‐ 0.98445 ) and pseudo-second-order ( R 2 = 0.94230 ‐ 0.99634 ) kinetic adsorption models, respectively. The results showed that the removal of fluoride by biosorbents prepared is effective and could be used for defluoridation of drinking water.

Water is essential for the life of all living organisms. But water with very high hardness (Ca2+ and Mg2+) is harmful to health. In addition, hard water clogs the pipes in the industries. This study was conducted to investigate the effectiveness of grafted potato starch as an adsorbent for hard water treatment. Four samples of well water from Nzuguni, Ng’hong’hona, Kisasa, and Swaswa of Dodoma municipal were analyzed by the EDTA titrimetric method. The results showed the highest hardness of 547 mg/L in the water sample of Ng’hong’hona from which hardness was removed. The maximum percentage removal of 74.50% was achieved at 80 minutes of optimum contact time. The optimum adsorbent dose is 3.5 g at which 80.7% of removal was achieved. The optimum temperature was 80°C at which 75.8% of removal achieved. An increase in pH increased the percentage of removal up to a pH of 12 with 71.1%. The data obtained showed that the adsorption process fitted Langmuir type II isothermal model and pseudo-second-order kinetic model with correlation coefficients of 0.9994 and 0.9940, respectively. Grafted potato starch has shown higher efficiency in hardness removal, and hence, this adsorbent is highly recommended for the treatment of hard water.

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This study conducted for the comparison of physico-chemical parameters between hot springs and borehole waters. Fourteen samples were collected at Mara, Shinyanga and Manyara in Tanzania. Multimeter used for the analysis of physical parameters pH, EC, TDS, salinity and turbidity. Titrimetric methods were used for the determination of Cl -, total hardness, Ca 2+ and Mg 2+ . UV-Vis. Spectrophotometric method for NO 3 -, SO 4 2-, F -, Fe 2+ and Mn 2+ and Flame Atomic Absorption Spectrometer for Cd 2+ , Zn 2+ , Ni 2+ , Cu 2+ and K + . The EC, TDS, salinity, turbidity, Cl -, NO 3 -, SO 4 2-, F -, Mn 2+ and Cu 2+ are higher (pH = 7.44-9.42, EC = 4251.33-15334 µS/cm, TDS = 2079-7526.7 mg/L, salinity = 2.2-8.67 ppt, Cl -= 189.3-3577.6 mg/L, SO 4 2-= 11.83-1353.33 mg/L, F -= 4.68-18 mg/L, Mn 2+ = 1.03-2.0 mg/L, Cd 2+ = 0.01-0.05 mg/L, Cu 2+ = 0.37-0.93 mg/L and K + = 44-100 mg/L) in hot springs than borehole waters (pH = 6.36-6.58, EC = 270.0-2674.64 µS/cm, TDS = 123.67-1305 mg/L, salinity = 0.03-1.37 ppt, Cl -= 6.25-659.93 mg/L, SO 4 2-= 28.92-493.33 mg/L, F -= 0.89-3.0 mg/L, Mn 2+ = 0.3-1.70 mg/L Cd 2+ = 0 mg/L, Cu 2+ = 0.49-0.64 mg/L and K + = 16-52 mg/L). The t-test at the probability 0.05 showed that there is significant difference of the parameters pH and Ni 2+ between hot spring and borehole waters. Some of the parameters are at higher levels than permissible values for both hot spring and borehole waters. Therefore, there is a need of treatment for these waters before using for domestic purpose.