Mn-Co-Ce/biochar based particles electrodes for removal of COD from coking wastewater by 3D/HEFL system: Characteristics, optimization, and mechanism.

In this work, the Mn, Co, Ce co-doped corn cob biochar (MCCBC) as catalytic particle electrodes in a three-dimensional heterogeneous electro-Fenton-like (3D-HEFL) system for the efficient degradation of coking wastewater was investigated. Various characterization methods such as SEM, EDS, XRD, XPS and electrochemical analysis were employed for the prepared materials. The results showed that the MCCBC particle electrodes had excellent electrochemical degradation performances of COD in coking wastewater, and the COD removal and degradation rates of the 3D/HEFL system were 85.35% and 0.0563 min-1 respectively. RSM optimized conditions revealed higher COD removal rate at 89.23% after 31.6 min of electrolysis. The efficient degradability and wide adaptability of the 3D/HEFL system were due to its beneficial coupling mechanism, including the synergistic effect between the system factors (3D and HEFL) as well as the synergistic interactions between the ROS (dominated by •OH and supplemented by O2•-) in the system. Moreover, the COD removal rate of MCCBC could still remain at 81.41% after 5 cycles with a lower ion leaching and a specific energy consumption of 11.28 kWh kg-1 COD. The superior performance of MCCBC, as catalytic particle electrodes showed a great potential for engineering applications for the advanced treatment of coking wastewater.

Effective Removal of Fe (III) from Strongly Acidic Wastewater by Pyridine-Modified Chitosan: Synthesis, Efficiency, and Mechanism.

A novel pyridine-modified chitosan (PYCS) adsorbent was prepared in a multistep procedure including the successive grafting of 2-(chloromethyl) pyridine hydrochloride and crosslinking with glutaraldehyde. Then, the as-prepared materials were used as adsorbents for the removal of metal ions from acidic wastewater. Batch adsorption experiments were carried out to study the impact of various factors such as solution pH value, contact time, temperature, and Fe (III) concentration. The results showed that the absorbent exhibited a high capacity of Fe (III) and the maximum adsorption capacity was up to 66.20 mg/g under optimal experimental conditions (the adsorption time = 12 h, pH = 2.5, and T = 303 K). Adsorption kinetics and isotherm data were accurately described by the pseudo-second-order kinetic model and Sips model, respectively. Thermodynamic studies confirmed that the adsorption was a spontaneous endothermic process. Moreover, the adsorption mechanism was investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results revealed the pyridine group forms a stable chelate with iron (III) ions. Therefore, this acid-resistant adsorbent exhibited excellent adsorption performance for heavy metal ions from acidic wastewater compared to the conventional adsorbents, helping realize direct decontamination and secondary utilization.