<p>Aqueous arsenic (As) pollution has become a hot issue for human health and environmental protection. In response to a circular economy, we have developed innovative spherical composites aerogel by adopting advanced sol-gel technology using KMnO₄ and calcium alginate (CA) modified pine cones (CPC-BC aerogel) and populous leaf (CPL-BC aerogel) biochars. The physicochemical properties and As(III) removal performance of CPC-BC aerogel spheres and CPL-BC aerogel spheres were systematically examined. Advanced characterization techniques like FTIR, XRD, XPS and SEM-EDS were used before and after adsorption to explain the possible mechanism. A series of batch sorption tests were carried out with optimal conditions of pH = 6.5, sorbent dosage = 2&#xa0;g L⁻¹, initial As concentration = 6 mg L⁻¹ and contact time of 2&#xa0;h. The CPC-BC aerogel spheres were rich in oxygen-containing functional groups and possessed higher pore size and cation exchange capacity, showing excellent adsorption potential (99%) in aqueous solution. Pseudo-second-order kinetics (<i>R</i>^<i>2</i> = 0.99) and Langmuir isotherm model (<i>R</i>^<i>2</i> = 0.99) showed a better fit with calculated adsorption data, indicating monolayer chemisorption is a dominant process. The synergistic role of CA and BC containing KMnO₄ can promote the binding of As(III) and the adsorption process. Finally, CPC-BC aerogel composite was directly applied to actual salt lake water and 88% of total As was removed. This study highlights the importance of novel composite applications for As sorption from aqueous solution as well as real salt lake water at the domestic/commercial scale.</p> Graphical abstract <p></p> <p>The graphical abstract provides a visual summary of raw waste (zero commercial value) used as biochar for ground and salt lake water pollution issues. Arsenic (As) is class (I) carcinogenic; therefore, it is important to develop a cost-efficient, selective and simple technique for the rapid sorption of As, especially As(III) from water. In this study, we used the sol-gel technique to create spherical aerogel composites (CPC-BC and CPL-BC) by using KMnO₄ modified biochar. Advanced analytical techniques such as FTIR, XRD, XPS, and SEM-EDS were used to examine the physicochemical characteristics. The pH 6.5, adsorbent dosage of 2&#xa0;g L⁻¹, As(III) concentration of 6&#xa0;mg L⁻¹, and contact period of 2&#xa0;h were shown to be the ideal parameters through batch studies. Large pore size, robust cation exchange capacity, and oxygen-rich functional groups demonstrated a high As(III) removal efficiency (99%) on the CPC-BC aerogel. Chemisorption predominance was shown by the pseudo-second-order model of adsorption kinetics (R² = 0.99). Monolayer adsorption was confirmed by the Langmuir isotherm (R² = 0.99). The efficiency of the CPC-BC aerogel in complicated conditions was demonstrated by its 99% removal of As(III) in synthetic solutions and 88% removal in actual salt lake water.</p>