Topic
Activated alumina
About: Activated alumina is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 31090 citations.
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TL;DR: Alum-impregnated activated alumina (AIAA) was investigated in the present work as an adsorbent for the removal of As(V) from water by batch mode as mentioned in this paper.
105 citations
TL;DR: In this paper, the synthesis and fluoride adsorption behavior of hydrous ferric oxide (HFO) are reported, and it is found that the highest adorption density for fluoride is found to be at pH 4.0.
Abstract: Groundwaters contaminated with excess fluoride (above 1.5 mg/L) posed some risks to the public health in India. Methods available for fluoride contaminated water treatment are cogaulation–filtration using alum + lime + bleaching powder (Nalgonda technique) and adsorption using activated alumina. Use of aluminium compounds for water treatment purpose needs replacement on neurological health problem. Objective to this, the synthesis and fluoride adsorption behavior of hydrous ferric oxide (HFO) are reported here. It is seen that fluoride adsorption density varies as a function of pH, contact time, aging time, drying temperature and particle size of HFO. Highest adsorption density for fluoride is found to be at pH 4.0. Effects of competing anions in removing fluoride from solution were tested. Arsenite, arsenate, phosphate and sulfate show strong interfering effect at high anions to fluoride molar ratio in solution. Adsorption of fluoride on HFO follows the Freundlich isotherm and the Lagergren first-order kinetic model. It was also determined that HFO is a better adsorbent in removing fluoride from high fluoride groundwater than some other adsorbents. Regeneration of fluoride-rich HFO results showed that 1.0 M NaOH solution could be used up to a maximum of 75% regeneration.
104 citations
TL;DR: In this paper, the effect of inlet flow rate, sorbent bed height and initial As(III) concentration on the adsorption of As (III) from aqueous solution were studied.
104 citations
TL;DR: In this paper, the optimal parameters affecting the adsorption of arsenic ions As(III) on iron oxide impregnated activated alumina (IOIAA) were determined by conducting batch and column experiments.
Abstract: The optimal parameters affecting the adsorption of arsenic ions As(III) on iron oxide impregnated activated alumina (IOIAA) were determined by conducting batch and column experiments. The adsorption of As(III) was strongly dependent on pH, temperature and initial adsorbate concentration. The adsorption process satisfied the Langmuir and Freundlich isotherms. Equilibrium studies were conducted to obtain the thermodynamic parameters and data showed the endothermic nature of adsorption. Kinetics studies showed that a pseudo first-order rate equation successfully described the adsorption process. Equilibrium was attained within 10 h and the time taken to attain equilibrium was independent of initial arsenite concentration. Column studies showed that adsorption was strongly dependent on empty bed contact time. Column design parameters such as the time taken for the establishment of primary adsorption zone, fractional capacity, length of primary adsorption zone and the percentage saturation at breakpoint were calculated to be in the range of 18.3 to 70.4 h, 0.39 to 0.63, 3.0 to 3.85 cm and 69.6 to 81.5%, respectively. The observations mentioned above provide a direct relationship between the length of the adsorption zone (δ) and percent saturation at break point.
103 citations
01 Jan 2018
TL;DR: Results implied that La doped Li/Al-LDH could serve as a potential adsorbent for efficient fluoride removal from water.
Abstract: In this study La intercalated Li/Al layered double hydroxide (LDH) was developed for efficient water defluoridation. The La-modified material, i.e., La doped Li/Al-LDH, exhibits more preferable fluoride adsorption than Li/Al-LDH in a broad pH range of 5–9, with the working capacity twice of the latter and seven times of magnitude higher than activated alumina. The fluoride removal kinetics is well fitted by pseudo-second order model, and the adsorption isotherm is well described by Freundlich model. Effect of pH and competing ions was examined during fluoride sequestration. The underlying mechanism for such enhanced adsorption of fluoride by La doped Li/Al-LDH was further revealed based on XPS and FTIR analysis. The presence of La and Al was found to be responsible for the satisfactory defluoridation of La doped Li/Al-LDH, and chloride replacement with fluoride occurred from both LDHs during fluoride adsorption. Also, the capacity of La doped Li/Al-LDH could be refreshed by alkaline solution (pH = 12) for cyclic runs. All the results implied that La doped Li/Al-LDH could serve as a potential adsorbent for efficient fluoride removal from water.
101 citations