Chitosan-modified biochar immobilised arsenic in root medium and enhanced the growth of zucchini (cv. Courgette d'Italie) seedlings

Contamination of arsenic (As) presents a health hazard that affects home gardeners neighbouring contaminated environments. The use of chitosan-modified biochar was investigated to immobilise As(V) from aqueous solution and zucchini seedlings (cv. Courgette d'Italie) were grown as a test crop. The results of characterisation revealed that the presence of chitosan on biochar (BR) surface improved its efficiency of As(V) immobilisation from the contaminated environment. A sorption study further showed that compared with the BR, (BR-C) chitosan-modified biochar (0.1 g) depicted the increased immobilisation of As(V) (10 ppm) from solution. Both Langmuir and Freundlich models fitted well, showing monolayer as well as multilayer sorption. BR-C showed a high Langmuir arsenic sorption capacity of 57.83 mg/g, which effectively decreased the level of As(V) toxicity. As demonstrated in results, As-stress reduced plant growth, seedling length, photosynthetic pigments, soluble sugar, increased hydrogen peroxide contents, and electrolyte leakage percentage. Simultaneously, BR and BR-C were effective against As(V) stress-induced changes in the zucchini plant. Collectively, the results of this study indicate that the modification of BR with chitosan can efficiently immobilised arsenic in the root medium and enhance growth of zucchini under controlled conditions by reducing the uptake of As(V).