Formable porous biochar loaded with La-Fe(hydr)oxides/montmorillonite for efficient removal of phosphorus in wastewater: process and mechanisms

Abstract

The development of biochar-based granule-like adsorbents suitable for scaled-up application has been attracting increasing attention in the field of water treatment. Herein, a new formable porous granulated biochar loaded with La-Fe(hydr)oxides/montmorillonite (LaFe/MB) was fabricated via a granulation and pyrolysis process for enhanced phosphorus (P) removal from wastewater. Montmorillonite acted as a binder that increased the size of the granulated biochar, while the use of Fe promoted the surface charge and facilitated the dispersion of La, which was responsible for selective phosphate removal. LaFe/MB exhibited rapid phosphate adsorption kinetics and a high maximum adsorption capacity (Langmuir model, 52.12 mg P g−1), which were better than those of many existing granulated materials. The desorption and recyclability experiments showed that LaFe/MB could be regenerated, and maintained 76.7% of its initial phosphate adsorption capacity after four adsorption cycles. The high hydraulic endurance strength retention rate of the developed material (91.6%) suggested high practical applicability in actual wastewater. Electrostatic attraction, surface precipitation, and inner-sphere complexation via ligand exchange were found to be involved in selective P removal over a wide pH range of 3–9. The thermodynamic parameters were determined, which revealed the feasibility and spontaneity of adsorption. Based on approximate site energy distribution analyses, high distribution frequency contributed to efficient P removal. The research results provide a new insight that LaFe/MB shows great application prospects for advanced phosphate removal from wastewater. Graphical Abstract

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

“…The positive values of DpH reflect the gradual increase in the hydroxide content, which is mainly dependent on ligand exchange. 48,69 Additionally, the accretion of La-MgAl-LDH/BC to the solution results in an increase in pH under both acidic and neutral conditions, while the final pH value of the solution is less than 8. Moreover, La-MgAl-LDH/BC has no significant effect to the pH of solution under alkaline conditions.…”

“…43,44 BC, being a high surface area and porous material, provides a large reactive area for effective modification of hydroxides and reduces the aggregation of LDH. [45][46][47][48][49][50][51][52] Alagha et al 53,54 synthesized biochar-MgAl LDH and magnetic Mg-Fe/LDH intercalated activated carbon for phosphate and nitrate removal. Yang et al 55 combined Zn/Al-LDH and BC for the synthesis of the BC-Zn/Al-LDH composites, with a phosphate adsorption capacity of 152.1 mg g À1 .…”

Thermal Air Oxidation-Mediated Synchronous Coordination and Carbonation of Lanthanum on Biochar toward Phosphorus Adsorption from Wastewater

“…Biochar-based adsorbents have attracted extensive attention in P removal and recovery, ,, attributed to the fact that biochar is easy to produce at lab or industrial scales via a variety of carbonization processes (e.g., hydrothermal carbonization, pyrolysis) with tunable physicochemical properties from abundant and sustainable biomass wastes for tailored applications. , Specifically, considering the agricultural functions of biochar, it is more competitive in P recovery as a slow-release fertilizer for agricultural applications . Thus, increasing attention has been paid on the development of biochar as the carrier of La species, i.e., La-doped biochar …”

Enhanced removal of estrogens from simulated wastewater by biochar supported nanoscale zero-valent iron: performance and mechanism

“…Biochar is a low cost and effective carbonaceous material for dispersing and stabilizing nZVI because of its surface charge, porous structures and abundant functional groups (Karunaratne et al 2022), which is obtained through carbonization of waste biomass in an oxygenlimited environment. Agricultural wastes, crustacean shells and animal feces are common biochar precursor materials (Li et al 2022;Sun et al 2022). Up to 1.5 million ton of walnut shell per year by 2020 was produced in China (Zhang et al 2015), with superior hydrophilicity, high specific surface area (Xu et al 2021) and wear resistance (Yu et al 2016), which was considered as an promising raw material of biochar.…”