Economically viable N-doped graphene aerogel for the photodegradation of structurally different dyes and a plant-model-based environmental assessment

Abstract

Photocatalysis has become a feasible process to tackle the increasingly severe water pollution. Despite the extensive research on photocatalytic degradation, very little progress has been made on the solar light induced degradation of complex mixtures of dyes. The mixture of harmful pollutant dyes is a critical concern of water pollution. Existing photocatalysts might be effective but not practical because of difficulty in separation from aqueous medium and requirement of a complex synthesis process and expensive raw materials. In order to enable easy separation of photocatalysts from aqueous medium without any further contamination, self-standing N-doped graphene aerogel (N-GA) was synthesized in an environment-friendly and cost-effective approach. The N-GA synthesized through a one-step process from biomass demonstrates remarkable photocatalytic efficiency in degrading a mixture of dyes with varying structures under sunlight-induced conditions. A photocatalytic degradation efficiency of ∼98% for CV, ∼98% for MB, and ∼99% for CR was achieved in 300 min from the mixture. Moreover, the N-GA has excellent reusability, sustainability, high stability and easy recyclability due to its structural integrity and distinctive inherent properties. Insights into the photocatalytic mechanism were gained from radical trapping experiments, and results showed the substantial influence of superoxide radicals. Furthermore, another novelty of this work is environmental assessment of treated water by checking the germination and growth of green gram beans in treated water. The treated wastewater showed enhanced germination and healthy growth of green gram beans compared to dye-contaminated water. These results reveal the environmental safety and practical compliance of N-GA for broad applications.