Green Fabrication of Porous Adsorbent with Structural Evolution of Mixed-Dimension Attapulgite Clay for Efficient Removal of Methylene Blue and Sustainable Utilization

In recent years, a variety of materials have been developed for water treatment, but green preparation and clean regeneration of absorbent materials have always neglected. Herein, porous materials were fabricated based on clean aqueous foam stabilized by natural plants Sapindus mukorossi (S. mukorossi) and mixed-dimensional attapulgite (MDAPT) clay. The effect of crystal defects of MDAPT clay on material preparation was investigated by the acid etching technique. The maximum adsorption capacity of the porous adsorbent prepared by the foam template for methylene blue was up to 847.7 mg/g, and the removal rate was >98% at ambient concentration. More importantly, the waste adsorbent was recycled for resource regeneration. The waste adsorbents were used as raw material to produce mineral biochar by a carbonization method for soil improvement. When the mineral biochar content was 1.5%, the pH of the soil increased from 4.51 to 6.36, and the electrical conductivity increased from 0.48 to 1.35 mS/cm. As a result of the improvement in soil structure and properties, the grown cabbage showed a significant increase in weight, length, and chlorophyll content. In conclusion, this work provides a sustainable idea for the green preparation of absorbent materials and for the recycling and reuse of waste materials.