Fluoride removal from water using high-activity aluminum hydroxide prepared by the ultrasonic method

Abstract

Different Al(OH) 3 powders were used as adsorbents for fluoride removal from water. The results showed that the defluoridation performance of ultrasonically prepared Al(OH) 3 (UAH) is much better than that of commercially available Al(OH) 3 and is comparable to that of activated alumina, because the ultrasonic waves effectively break the agglomerates in the suspension so that the UAH particles are fine and have a beneficial phase constituent. Furthermore, the residual aluminum concentration in aqueous solution after defluoridation by Al(OH) 3 was found to be one order of magnitude lower than that obtained with activated alumina which is below the World Health Organization (WHO) guideline for aluminum (0.2 mg L À1 ) in drinking water. The defluoridation dynamics and mechanism for UAH are discussed in detail.

Addressing technical barriers for reliable, safe removal of fluoride from drinking water using minimally processed bauxite ores

“…The impacts of co-occurring ions on fluoride adsorption on aluminum-based adsorbents have also been explored in a preliminary manner by other groups. Studies on adsorbents including alum sludge, alumina-coated magnetite nanoparticles, aluminum hydroxide, activated alumina, and bauxite consistently find that of all common anions in groundwater, phosphate concentrations (tested between 10 and 300 mg/L) have the greatest impact on fluoride adsorption ( Sujana and Anand, 2011 ; Sujana et al, 1998 ; Gai et al, 2015 ; Chai et al, 2013 ; Tang et al, 2009 ). In addition, a study of high-activity aluminum hydroxide suggests that phosphate inhibits fluoride adsorption by binding to the surface of the aluminum hydroxide ( Gai et al, 2015 ).…”

“…Studies on adsorbents including alum sludge, alumina-coated magnetite nanoparticles, aluminum hydroxide, activated alumina, and bauxite consistently find that of all common anions in groundwater, phosphate concentrations (tested between 10 and 300 mg/L) have the greatest impact on fluoride adsorption ( Sujana and Anand, 2011 ; Sujana et al, 1998 ; Gai et al, 2015 ; Chai et al, 2013 ; Tang et al, 2009 ). In addition, a study of high-activity aluminum hydroxide suggests that phosphate inhibits fluoride adsorption by binding to the surface of the aluminum hydroxide ( Gai et al, 2015 ). These studies also consistently agree that nitrate has little to no effect on fluoride removal; the same is consistently found with chloride ( Cherukumilli et al, 2017a ; Sujana and Anand, 2011 ; Sujana et al, 1998 ; Gai et al, 2015 ; Chai et al, 2013 ; Tang et al, 2009 ).…”

“…In addition, a study of high-activity aluminum hydroxide suggests that phosphate inhibits fluoride adsorption by binding to the surface of the aluminum hydroxide ( Gai et al, 2015 ). These studies also consistently agree that nitrate has little to no effect on fluoride removal; the same is consistently found with chloride ( Cherukumilli et al, 2017a ; Sujana and Anand, 2011 ; Sujana et al, 1998 ; Gai et al, 2015 ; Chai et al, 2013 ; Tang et al, 2009 ).…”

“…A study on activated alumina and activated bauxite concluded that sulfate had no effect on fluoride removal using either adsorbent ( Choi and Chen, 1979 ). On the other hand, several studies on adsorbents such as an alumina/chitosan composite, ultrasonically prepared high activity aluminum hydroxide, and alum sludge, the waste material of alum manufacture, find that sulfate concentrations as low as 10 mg/L reduce fluoride adsorption, though in each case sulfate competes to a lesser extent than phosphate ( Gai et al, 2015 ; Viswanathan and Meenakshi, 2010 ). In addition, many studies only look at the effects of sulfate at concentrations of up to 200 mg/L, which is lower than what may be found in many groundwater sources (the US EPA secondary drinking water standard is 250 mg/L ( United States Environmental Protection Agency, ), and many groundwater matrices contain more than double this amount) ( World Health Organization, 2004a ).…”

Effect of storage environment on hydrogen generation by the reaction of Al with water

“…Al is the most abundant metal in the earth's crust ($8.1%) and is widely used as a building material, in aircra, industrial and civil products, paint, underwater propellant and high explosive, etc. [1][2][3][4][5] In the past few years, Al metal as a hydrogen-generation material has attracted considerable attention due to its relatively low cost and high productivity of H 2 in that one kg of Al reacts with water to generate as much as 0.11 kg H 2 . 6,7 Usually, there is a compact and strongly adhesive passive lm on an Al surface upon exposure to atmosphere, inhibiting the direct reaction of Al with water.…”