Amorphous pectin/calcium magnesium carbonate @ konjac glucomannan for recovery phosphate from aqueous

To safeguard water quality and sustainable phosphorus cycling, it is imperative to recover phosphorus from highcontent wastewater, particularly livestock wastewater, considering the low tolerance threshold for phosphate in surface water (below 0.5 mg/L). Calcium carbonate and magnesium carbonate possess considerable potential for phosphate adsorption; however, their crystalline nature diminishes the reactivity of calcium and magnesium, resulting in the limited phosphate adsorption capacity. In this study, a novel phosphate adsorbent (PCCM@K) was synthesized through co-precipitation involving Ca, Mg, and pectin, followed by direct coating with konjac glucomannan, which eliminated the need for separation and cleaning steps. Pectin macromolecules interact with Ca and Mg to yield amorphous minerals, thereby enhancing the pore structure. The assessment of the phosphate adsorption performance of PCCM@K reveals robust alkali release, stable adsorption across a broad pH range (3-12), high adsorption capacity (61.9 mg-P/g), minimal interference from coexisting ions, and effective phosphate recovery in the actual biogas slurry. The primary mechanism underlying phosphate adsorption is chemisorption. During the adsorption process, ligand exchange takes place between carbonate and phosphate, leading to an increase in solution pH and the immobilization of phosphate via inner-sphere complexation with Ca and Mg. Overall, PCCM@K exhibits considerable potential for phosphorus recovery from wastewater, highlighting its significance in promoting environmentally sustainable practices.