Corncob-to-xylose residue (CCXR) derived porous biochar as an excellent adsorbent to remove organic dyes from wastewater

Adsorption Performance of Methylene Blue by KOH/FeCl3 Modified Biochar/Alginate Composite Beads Derived from Agricultural Waste

In this study, high-performance modified biochar/alginate composite bead (MCB/ALG) adsorbents were prepared from recycled agricultural waste corncobs by a high-temperature pyrolysis and KOH/FeCl3 activation process. The prepared MCB/ALG beads were tested for the adsorption of methylene blue (MB) dye from wastewater. A variety of analytical methods, such as SEM, BET, FTIR and XRD, were used to investigate the structure and properties of the as-prepared adsorbents. The effects of solution pH, time, initial MB concentration and adsorption temperature on the adsorption performance of MCB/ALG beads were discussed in detail. The results showed that the adsorption equilibrium of MB dye was consistent with the Langmuir isothermal model and the pseudo-second-order kinetic model. The maximum adsorption capacity of MCB/ALG−1 could reach 1373.49 mg/g at 303 K. The thermodynamic studies implied endothermic and spontaneous properties of the adsorption system. This high adsorption performance of MCB/ALG was mainly attributed to pore filling, hydrogen bonding and electrostatic interactions. The regeneration experiments showed that the removal rate of MB could still reach 85% even after five cycles of experiments, indicating that MCB/ALG had good reusability and stability. These results suggested that a win-win strategy of applying agricultural waste to water remediation was feasible.

Intermittent ultrasound retains cellulases unlock for enhanced cellulosic ethanol with high-porosity biochar for dye adsorption using desirable rice mutant straw

In this study, optimal ultrasound pretreatment was performed with recalcitrance-reduced rice mutant straw to effectively extract lignin and hemicellulose for improved cellulose accessibility. Intermittent ultrasound-assistant enzymatic hydrolyses were followed to maintain more cellulases unlock and less cellulose surface block with lignin for raised hexose yield at 81 % (% cellulose) and bioethanol concentration at 9.9 g/L, which was higher than those of other mechanical pretreatments as previously conducted. Using all enzyme-undigestible lignocellulose residues, this work generated the biochar with the highest porosity (S_BET at 2971 m²/g) among all biomass-based biochar obtained from previous studies. Furthermore, the biochar were respectively examined with high adsorption capacity for Congo red and methylene blue at 7946 mg/g and 861 mg/g. Therefore, this study has demonstrated a green-like process technology for high-yield bioethanol and high-porosity biochar with full biomass utilization by integrating optimal ultrasound pretreatment with intermittent ultrasound-assistant enzymatic hydrolyses of recalcitrance-reduced lignocellulose in crop straws.

Regeneration of Washing Effluents for Remediation of Petroleum-Hydrocarbons-Contaminated Soil by Corncob-Based Biomass Materials

Surfactant-enhanced soil washing is an effective remediation method for petroleum-hydrocarbons-contaminated soil. The residual petroleum hydrocarbons in the washing effluents reduce the elution ability of the washing effluents and cause secondary pollution to the environment. In this work, modified corncobs were prepared and used as selective adsorbents to remove the residual petroleum hydrocarbons in washing effluents. The structure of adsorbent was characterized and the adsorption conditions were optimized. With the adsorption by corncob-based adsorbents, washing effluents can be regenerated and recycled. After five cycles, the recovery efficiency of the washing effluents is still as high as 75.4%. The optimal adsorbent linear alkylbenzene sulfonates (LAS-Cb) also exhibited excellent recyclability, which can be recycled five times. The selective adsorption mechanism of the LAS-Cb for petroleum hydrocarbons in washing effluents, related to its huge hydrophobic core and surface electronegativity, is proposed.