One of the major concerns for utilizing ionic liquid on an industrial scale is the cost involved in the production. Despite its proven pretreatment efficiency, expenses involved in its usage hinder its utilization. A better way to tackle this limitation could be overcome by studying the recyclability of ionic liquid. The current study has applied the Box–Behnken design (BBD) to optimize the pretreatment condition of rice straw through the usage of 1-ethyl-3-methylimidazolium acetate (EMIM-Ac) as an ionic liquid. The model predicted the operation condition with 5% solid loading at 128.4 °C for 71.83 min as an optimum pretreatment condition. Under the optimized pretreatment condition, the necessity of the best anti-solvent was evaluated among water, acetone methanol, and their combinations. The study revealed that pure methanol is the suitable choice of anti-solvent, enhancing the highest sugar yield. Recyclability of EMIM-Ac coupled with anti-solvent was conducted up to five recycles following the predicted pretreatment condition. Fermentation studies evaluated the efficacy of recycled EMIM-Ac for ethanol production with 89% more ethanol production than the untreated rice straw even after five recycles. This study demonstrates the potential of recycled ionic liquid in ethanol production, thereby reducing the production cost at the industrial level.

Chondroitin sulfate is currently one of the bioactive compounds obtained from different natural materials with high benefit in human medical treatment and pharmaceutical. However, the natural concentration of chondroitin sulfate in high cost raw material is low and this situation makes the commercialization become difficult. This study focused on production of chondroitin sulfate isolated from Bohadschia argus using enzyme-assisted extraction methodology. Optimization experiments were conducted based on Response Surface Methodology (RSM) using Box–Behnken design (BBD). Three important extraction parameters, including enzyme concentration (X1: 0.05-0.5 %), Time (X2: 0.25–3 h), and temperature (X3: 55–65 °C) were varied to obtain maximum chondroitin sulfate yields. The RSM optimized model obtained from statistical analysis presented the high correlation coefficiency (R2) at 0.7508, advocating the significance of the model. The optimum extraction conditions were selected as enzyme concentration of 0.48% with extraction time of 1.01 h. at an extraction temperature of 56.53°C. Under these conditions, the experimental yield of chondroitin sulfate was 415.59 mg/100g dry, which is in good agreement with the value predicted by the model.