Green synthesis of ice-templated lotus starch–bentonite cryogels for sustainable and energy-efficient VOC capture

Abstract

Sustainable adsorbents for industrial volatile organic compound (VOC) control are urgently needed to balance efficiency and operational economy. This report describes an eco-friendly strategy for fabricating hierarchical porous bentonite (Bt) via green ice-templating using lotus root starch as a biomass crosslinker. The optimized material exhibits a well-defined lamellar-bridging network with a specific surface area of 71.3 m² g⁻¹ and a pore volume of 0.118 cm³ g⁻¹.This adsorbent exhibits high toluene capacity (53.8 mg g⁻¹; 4.7× raw Bt) with polarity-driven selectivity for chlorobenzene (54.3 mg g⁻¹) > toluene > benzene (46.2 mg g⁻¹), facilitated by multiscale transport and cation-polar molecule interactions. Notably, the material enables humidity-resistant operation and low-energy regeneration at 110 °C while retaining 78% capacity after 10 cycles. With its natural composition, low-energy synthetic route avoiding calcination, and efficient regeneration profile, this work provides a sustainable and cost-effective material platform toward next-generation low-carbon air pollution control systems.