Mg-Al Layered Double Hydroxide Doped Activated Carbon Composites for Phosphate Removal from Synthetic Water: Adsorption and Thermodynamics Studies

Abstract

Increased phosphate concentration in water bodies has led to eutrophication, and its removal is an inevitable requirement of sustainable wastewater purification systems. In this study, MgAl layered doubled hydroxide (LDH) composites doped on the surface of activated carbon (AC/MgAl LDH) with various (Mg + Al) total metal loading (5 wt%, 10 wt%, and 15 wt%) were prepared by the co-precipitation method. The influence of (Mg + Al) total metal loading onto AC was examined to remove phosphate ions from aqueous solutions. The effect of adsorption parameters, including adsorbent dosage, initial solution pH, initial phosphate concentration, contact time, and experiment temperature, were investigated via batch adsorption experiments. The adsorption results demonstrated that the phosphate adsorption capacity significantly improved with increasing the (Mg + Al) metal loading on the surface of AC. The maximum Langmuir phosphate adsorption capacity was 337.2 mg phosphate per gram of AC/MgAl-3 LDH composite (15 wt% Mg + Al) composite at pH ~6.3, 22 °C, and 1 g/L of adsorbent. The kinetic data were best fitted with the pseudo-second order model. The initial solution pH notably influenced the phosphate removal by AC/MgAl-3 LDH composite with a maximum removal at pH 2.3. According to the spent adsorbent characterization results, the dominant mechanisms of phosphate removal by AC/MgAl-3 LDH were electrostatic interactions, ion exchange, and inner-sphere complexation. The phosphate adsorption capacity was gradually increased with increasing the experiment temperature, suggesting an endothermic adsorption process. Overall, the AC/MgAl LDH composites pave the way for an effective strategy for phosphate removal from aqueous solutions.

Continuous Phosphate Removal and Recovery Using a Calcium Silicate Hydrate Composite Monolithic Cryogel Column

“…Adsorption is one of the most appropriate technologies due to its simplicity of use, high removal effectiveness, and economic affordability [ 15 , 16 , 17 , 18 ]. To adsorb phosphate from aqueous solutions, various materials have been investigated in batch experiments, such as chitosan [ 19 ], activated carbon [ 20 , 21 ], silica gel [ 22 ], clays [ 4 , 23 ], zeolites [ 24 , 25 ], carbon nanotubes [ 26 , 27 ], coal [ 28 , 29 ], and fly ash [ 30 , 31 ].…”

Deposition of layered double hydroxide on non‐pretreated carbon cloth using lactate salts as raw materials

“…This achievement was not previously accomplished using the commonly used chlorides and nitrides as Mg and Al sources for LDH deposition. Given that the deposition of LDH on carbon materials have been widely investigated for preparing possible materials as supercapacitor and environmental purification, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] the present method paves the way to a facile and eco-friendly method for depositing inorganic particles onto hydrophobic surfaces.…”

“…[6][7][8][9][10] Herein, we devoted special attention to the deposition of layered double hydroxide (LDH) 1,11 on non-pretreated carbon cloth (CC) using lactate salts as raw materials. LDH displays various combinations of components, including MgAl [12][13][14][15][16][17] and NiFe, 6 due to the stacked octahedral layers of metal hydroxides. In these layers, a portion of divalent metal cation (M 2+ ) is substituted with trivalent cations (M 3+ ) to generate positive layer charges that are compensated with interlayer exchangeable anions.…”

Co-Al layered double oxide activated carbon composite for eliminating lead ions from water

“…According to the categorization of the IUPAC, and as depicted in Figure 1(a), the raw AC exhibited type IV isotherm with an H4 hysteresis loop usually obtained for mesoporous materials [34]. While the Co-Al LDO/AC composite, shown in Figure 1(b), demonstrates type II adsorption isotherm with an H3 hysteresis loop representing a microporous structure material [33]. While in the BET-SA result, a reduction in the SA was noticed where the raw AC and Co-Al LDO/AC exhibited 829.6 and 189.4 m 2 /g, respectively.…”