Adsorptive separation of phosphate oxyanion from aqueous solution using an inorganic adsorbent

Abstract

Phosphate removal from aqueous solution was explored using granular ferric hydroxide (GFH) as an inorganic adsorbent. Adsorption, desorption and kinetic studies were conducted on laboratory scale to evaluate the performance of GFH as an adsorbent for low concentrations of phosphate solution. The effect of pH on adsorption was investigated, and phosphate uptake was shown to decrease with an increase in solution pH, with maximum removal seen to occur at pH 3. The experimental data best fit the Temkin isotherm at both pH 3 and 4. Uptake of phosphate by GFH follows second-order kinetics, with the small particle range (76-200 microm) removing phosphate from the solution more rapidly than the larger particle range (710-850 microm). The kinetic results suggest that intra-particle diffusion is an important factor in phosphate adsorption onto GFH. Thermodynamic parameters (DeltaG degrees, DeltaH degrees, DeltaS degrees) were evaluated, and the results indicated that the adsorption process was endothermic and spontaneous. This study demonstrates that GFH has potential to be used as a cost-effective adsorbent for phosphate removal from aqueous solution.

Adsorption Kinetic and Thermodynamic Studies of Phosphate onto Tantalum Hydroxide

“…Adsorption of anion onto oxidic surface involves surface complexation phenomenon in the adsorption process. Previous studies (Namasivayam and Prathap, 2005;Saha et al, 2010) showed that the presence of oxidic adsorbents (e.g., hydroxylated mineral) plays an important role in the removal of anions from aqueous solutions. In this case, the adsorbent tantalum hydroxide is present in the following forms depending on the pH of the solution:…”

Granulation of Cobalt-containing Nickel Hydroxide with Polyethylene Terephthalate and its Phosphate Ion Adsorption Capability

“…Two models were used, with the results shown in Table 3. The Langmuir isotherm was applicable in cases where homogeneous adsorption occurred, with all adsorbed molecules having equal sorption activation energies [47,48].…”

“…The Freundlich isotherm is used to describe systems of heterogeneous nature [50,51]. As the Freundlich equation is exponential, it assumes that as the adsorbate concentration increases, its concentration on the adsorbent surface increases as well [47]:…”

Adsorption of Phosphate in Aqueous Phase by Biochar Prepared from Sheep Manure and Modified by Oyster Shells

“…27,28 Metal and metal-oxide adsorbents have high adsorption capacity and fast adsorption speed for phosphate, but they are easy to agglomerate, and excessive accumulation of most metals will cause toxicity. 29,30 Therefore, in contrast, the application of solid waste adsorption materials based on biochar can also alleviate the environmental pollution problem on the premise of ensuring the adsorption capacity and not producing secondary pollution, thus killing two birds with one stone. 11−14 Biochar modification by Ca is also promising as this method does not generate any toxic waste or byproducts and is easy to accomplish.…”