A sustainable ecofriendly alternative for reactive blue 19 removal utilizing a novel biomass Rhizoclonium hieroglyphicum and its reuse potential for ecological implications

In the present investigation, an attempt was made to study the impact of the green algae Rhizoclonium hieroglyphicum for the removal of reactive blue 19 (RB19) dye from an aqueous solution and to assess the reuse potential in environmental field. Optimization of the process variables, namely, dye concentration (100–500 mg/L), biosorbent concentration (100–900 mg/L), pH (3–12), and incubation time (24–120 h) for RB19 removal was performed using response surface methodology (RSM) under room temperature. The dye adsorption mechanism was assessed through the application of isotherm, kinetics, and thermodynamic models. The interaction between the adsorbate and biosorbent was confirmed through analytical methods. The recycling and regeneration efficiency of the dye adsorbed alga was evaluated using different eluents. The nature of the treated and untreated dye solutions was assessed in terms of microbial toxicity and phytotoxicity. The dye desorbed alga was further subjected to composting and the macronutrients were analyzed. To support the results of in vitro investigation, in silico docking was performed. Results through RSM revealed that maximum decolorization (88%) was recorded in the aqueous solution amended with 300 mg/L dye and 500 mg/L biosorbent at pH 8 on 72 h at 25 °C. The empirical data exhibited strong conformity with Freundlich isotherm and the pseudo-second-order kinetic models. Thermodynamic investigations disclosed that the adsorption process was characterized as endothermic, spontaneous, and favorable. Recycling studies revealed maximum dye recovery (84%) when 0.1 M HCl was used as an eluent with 79% regeneration efficiency. UV–visible, FT-IR, and SEM analyses elucidate the interaction between the biosorbent and adsorbate corroborating the decolorization process facilitated by R. hieroglyphicum. Microbial and phytotoxicity study substantiated the non-toxic nature of the treated dye. The values obtained in the physicochemical analysis of algal compost can help to improve the soil fertility and plant growth. The result of the docking analysis demonstrated a significant binding energy between RB19 and the R. hieroglyphicum protein (heat shock protein 70) affirming a robust interaction. The present study is the first report on the removal of reactive blue 19 utilizing R. hieroglyphicum which can bolster their resilience and can promote the wellbeing of the freshwater environment grappling with pollution issues.