Production of versatile biosorbent via eco-friendly utilization of non-wood biomass

Biomass accumulation is an urgent issue of sustainable nature management because its conglomerations occupy vast agricultural areas. Since the non-wood biomass is a source of valuable polymer materials - cellulose and lignin, the development of technologies for this waste processing is an important scientific task. This study proposes an eco-friendly method of Juglans Regia L. walnut shells and Prunus Armeniaca L. apricot kernels processing, which ensures their complete utilization with the production of an effective biosorbent and liquid multicomponent fertilizer. At the first stage, processing of raw biomass with a solution of 25 vol% NH4OH with a specific NH3 consumption of 0.72 g g(-1), provides a delignification degree of 85 %, and the specific output of cellulose reaches at least 90 %. Delignification significantly increases the biomass' specific surface up to 110 m(2) g(-1) and iodine number up to 32 mg g(-1), however, exchange capacity decreases by 45-55 %. To improve ion exchange properties, the intermediate cellulose product was phosphorylated in an aqueous solution with urea addition. Obtained biosorbent has a capacity for heavy metals ions up to 270 mg g(-1), and uranium - 196 mg g(-1). Biosorbent is also capable of removing numerous metal cations and various synthetic dyes from the water, so it can be used in water purification technology. An environmentally friendly method for waste solutions disposal ensures the production of liquid complex fertilizer containing 17 wt% N and 14 wt% P. Feeding grain crops with this fertilizer increases the plants' length by 40-75 %, and their total weight by 20-30 %.

Automated summary

This study proposes an eco-friendly method for processing walnut shells and apricot kernels waste, producing an effective biosorbent and liquid fertilizer. The biosorbent has a high capacity for heavy metal ions and can remove various pollutants from water. The liquid fertilizer promotes plant growth significantly.