Enhancing phosphate removal performance in water using La–Ca/Fe–LDH: La loading alleviates ineffective stacking of laminates and increases the number of active adsorption sites

Rapid and efficient removal of phosphate by La-doped layered double hydroxide/biochar from aqueous solution

“…36,71 As La-doped into LDH materials, both La–MgAl–LDH and La–MgAl–LDH/BC alleviate the inhibitory effect of CO 3 2− , due to the strong binding capacity of La and phosphate, creating highly recognized active sites and alleviating the competitive effect. 40,72 Even though the CO 3 2− ions had inhibition on the La–MgAl–LDH/BC adsorption for phosphate, the adsorption capacity of La–MgAl–LDH/BC could still reach 75% of that without co-existing anions, and La–MgAl–LDH/BC shows stronger interference than LDH, implying that La–MgAl–LDH/BC has good ion-selectivity. In short, considering that the anion concentration in actual water is much lower than the concentration in this experiment, we can infer that La–MgAl–LDH/BC is appropriate for phosphorus pollution treatment.…”

Removal of Low-Concentration Phosphate Adsorption by La–Ca–CO3 Material: Performance, Mechanism, and Applicability

“…For the original adsorbent, only the crystalline phase of CaCO 3 can be seen in the adsorbent, but no crystalline phase of La 2 (CO 3 ) 3 appears, indicating that La may be attached to the surface of CaCO 3 in an amorphous phase. 19 Moreover, after the phosphate adsorption in the case of 2 mg•P/L of initial phosphate concentration and 0.1 g/L of adsorbent dosage, according to the experimental product derived from the adsorbent's X-ray powder diffraction peak curve bread is amorphous with no diffraction peak of CaCO 3 , La 2 (CO 3 ) 3 , and Ca 10 (PO 4 ) 6 (OH) 2 .…”

“…This indicates that the adsorption process of phosphate onto La−Ca−CO 3 adsorbent involves monolayer adsorption. 19 Moreover, the value of R L is 0.0054, suggesting that the phosphate adsorption on La−Ca−CO 3 adsorbent is favorable, which also indicates that there is a higher interaction between adsorbent and phosphate. 9,30 The values of Langmuir and Freundlich model constants are summarized in Table 3, in which the maximum adsorption capacity calculated from Langmuir was 44.96 mg• P/g, which is higher than those reported for La-doped adsorbents such as La(OH) 3 -modified canna biochar (37.37 mg•P/g), 31 La-coal fly ash�blast furnace cement composite (24.9 mg P/g), 9 and La-lignocellulose biochar (36.06 mg•P/ g).…”

Layered Double Hydroxides for Regulating Phosphate in Water to Achieve Long-Term Nutritional Management

“…14,67,97−99 For instance, the PSO model can well-fit the phosphate removal by La-CaFe-LDH reported by Yuan et al, indicating a chemisorption process. 100 Interestingly, the Elovich model, an empirical equation considering the contribution of desorption, is reported to be the most suitable for describing the kinetic phosphate adsorption onto Ca 2 Al-LDH. 101 − of −368 kJ mol −1 , and Cl − of −347 kJ mol −1 ), makes it more difficult to move across from liquid phase to other phases.…”

“…Four classical kinetic theories are widely applied to modeling phosphate adsorption systems by LDHs: pseudo-first-order, pseudo-second-order, Elovich, and the intraparticle diffusion models, , which are expressed by the following equations: where q e and q t (mg g –1 ) are the amount of adsorbed phosphate at equilibrium and time t , respectively; k 1 (h –1 ) and k 2 (g mg –1 h –1 ) are the rate constants of the PFO and PSO models, respectively; a (mg g –1 h –1 ) is the initial adsorption rate constant of the Elovich model; b (mg g –1 ) is the desorption rate constant; k i is the intraparticle diffusion rate constant (mg g –1 h –1/2 ); and C i represents a constant in the intraparticle diffusion equation . Most published works use the PSO model to predict the experimental phosphate adsorption data by LDHs and calculate the adsorption rate constants. ,,− For instance, the PSO model can well-fit the phosphate removal by La-CaFe-LDH reported by Yuan et al, indicating a chemisorption process . Interestingly, the Elovich model, an empirical equation considering the contribution of desorption, is reported to be the most suitable for describing the kinetic phosphate adsorption onto Ca 2 Al-LDH .…”