Fluoride Removal Performance of a Synthesized Adsorbent

Water Science and Technology

Gupta

2022

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In the present study coagulation process was used as pretreatment for the RO membrane with turbid raw water collected from Bisalpur Dam, Rajasthan, India. To optimize coagulation performance, three kinds of coagulants, namely, Alum (commercially available), synthesized inorganic polymeric coagulant-medium basicity (IPC-M), and inorganic polymeric coagulant-ultra high basicity (IPC-UH) were examined for turbidity removal with varying operating parameters. It was observed that in the optimum pH range of 6–7, the IPC-UH resulted as the best performing coagulant with 0.99 mg/L equivalent Al2O3 dose revealing 2 NTU residual turbidity and residual aluminium of 0.001 mg/L. Moreover, Langelier saturation index and Ryznar stability index values were evaluated at optimum conditions of all the three coagulants proclaiming negligible scaling potential. Furthermore, the coagulant-treated water (100 L) was fed to the RO membrane, and the performance was noted in terms of flux, pressure, and TDS. It was observed that IPC-UH has the lowest reduction in permeate flux of 0.78 L/min/m2 compared to commercially available coagulant alum (0.90 L/min/m2). Also, the increased feed pressure was observed for all the coagulants treated water with the lowest value of 2.3 kg/cm2 for IPC-UH, which was 2.5 kg/cm2 for Alum (commercially available coagulant). Henceforth, integration of coagulation before the RO system resulted in effective pretreatment of turbid water with very minute scaling.

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Section: Introductionmentioning

confidence: 99%

Development of an integrating coagulation and reverse osmosis system to treat highly turbid water using synthesized coagulants

Water Science and Technology

Gupta

2022

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“…Fluorides occur mainly as cryolite (NaAlF 6 ), fluorspar (CaF 2 ), sellaite (MgF 2 ), and fluoroapatite [3Ca 3 (PO 4 ) 2 Ca(F,C l2 )] in different rocks. , Groundwater generally consists of fluoride because it has favorable conditions for the dissolution of fluoride in the underground strata; in addition, high fluoride contents from industrial discharge are expelled to the water bodies, thus increasing the fluoride contents in groundwater. , High fluoride concentration in drinking water is of major concern as people from developing countries are dependent on groundwater, usually untreated, for their daily consumption. , Fluoride removal is a huge problem for many developing countries as they lack the necessary infrastructure and expertise. In countries such as Middle East, South America, and United States and Asian countries such as Ethiopia, Pakistan, India, Iran, China, and Kenya, fluoride removal is a serious issue. − The high concentration of fluoride in drinking water makes the teeth and bones of the consumer brittle, harder, and denser as the fluoride deposits in the form of calcium fluorapatite.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Plausible Mechanism of the Synthesized Inorganic Polymeric Coagulant and Its Application toward Fluoride Removal from Drinking Water

Maheshwari

et al. 2020

Ind. Eng. Chem. Res.

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Fluoride, an anionic pollutant, existing in concentrations exceeding the allowed limit of 1.5 mg/L in drinking water, has been reported to cause detrimental impact on human health. The traditionally employed methods for water defluoridation mostly involve Al-based coagulants, which however face some limitations, such as requirement of relatively high dosage and production of excessive amounts of chemical sludge posing a problem of its safe disposal. In this study, two inorganic polymeric coagulants of medium (IPC-M) and ultrahigh basicity (IPC-UH) were synthesized using polymerization of aluminum trihydrate (Al 2 O 3 •3H 2 O) with an aqueous solution of 32% hydrochloric acid. The basicity of coagulants was increased by manipulating the redox reaction of the product with the aluminum metal. The synthetic coagulants were analyzed using various characterization techniques, viz., Fourier transform infrared spectroscopy, electrospray ionization−mass spectrometry, and field emission scanning electron microscopy with electron-dispersive X-ray spectroscopy, and the main physicochemical properties such as % Al 2 O 3 , relative basicity, and % chloride. The aluminum species distribution was assessed by the ferron assay, and their electrochemical properties such as dissolved charge, conductivity, acidity, and pH were also measured. The application of IPCs was explored for their fluoride removal efficacy using jar tests. The outcome showed that IPC-M was the most efficient when applied in a pH range relevant to fluoride-containing water as it was the only coagulant that showed increasing efficiency at pH values > 7. The uptake capacity of coagulants for using synthetic samples prepared in Milli-Q water containing 9 mg/L of raw fluoride concentrations to achieve residual concentration of less than 1.5 mg F/L at the pH value 6.5 ± 0.1 was calculated as 87.68 and 68.48 mg F/g Al 2 O 3 for IPC-M and IPC-UH, respectively, which were higher than the reported values of 37.42 and 37.75 mg F/g Al 2 O 3 for alum and polyaluminum chloride in an earlier published paper. The residual aluminum concentration in these experiments ranged at 30 ± 5 and 20 ± 5 μg Al/L, respectively, for IPL-M and IPL-UH, which were well within the WHO norm for drinking water (<200 μg/L), indicating their immense application in the field.

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Removal of fluoride from water by using a coagulant (inorganic polymeric coagulant)

Maheshwari

et al. 2020

Environ Sci Pollut Res