A novel biochar composite derived from oil-based drill sludge and cuttings: Structural characterization and electrochemical properties

How to dispose of large quantities of hazardous shale gas drilling waste is an important worldwide problem facing the oil and gas industry. In this study, we report an environmentally friendly and low energy consumption approach (carbonization followed by activation) to convert oil-based drill sludge (OBDS) and oil-based drill cuttings (OBDCs) into biochar composites and investigate the effect of hydrofluoric acid (HF) acidification on them. The biochar composites were prepared using the OBDS, OBDCs, the mixtures of OBDS and OBDCs, and HF treatment the mixtures were named OS, OC, OSC, and OSC-HF, respectively. The characterization result of synthesized biochar composites indicated that the OSC had a larger specific surface area and a higher degree of graphitization. The composites mainly consisted of SiO2 and BaSO4, except for biochar. The OSC electrode exhibited the highest oxygen evolution potential (1.72 V vs Ag/AgCl) and the lowest charge transfer resistance compared with OS, OC, and OSC-HF electrodes, implying that SiO2 plays an important role in electrochemical performance. Using the OSC electrode as an anode, the chemical oxygen demand removal efficiency of the OBDS supernatant was 79.4 ± 0.95%. Further, the OSC electrode could maintain higher degradation efficiency and stability after the fifth reuse. The study provides a promising route for the proper disposal and resource utilization of OBDS and OBDCs and proposes a novel biochar compound as an electrode for the efficient treatment of wastewater. Moreover, this work highlights the important significance of the simultaneous resource utilization of waste and the treatment of wastewater using waste materials.

Band-Gap Engineering of Layered Perovskites by Cu Spacer Insertion as Photocatalysts for Depollution Reaction

A multi-step ion-exchange methodology was developed for the fabrication of Cu(LaTa2O7)2 lamellar architectures capable of wastewater depollution. The (001) diffraction line of RbLaTa2O7 depended on the guest species hosted by the starting material. SEM and TEM images confirmed the well-preserved lamellar structure for all intercalated layered perovskites. The UV–Vis, XPS, and photocurrent spectroscopies proved that Cu intercalation induces a red-shift band gap compared to the perovskite host. Moreover, the UV–Vis spectroscopy elucidated the copper ions environment in the Cu-modified layered perovskites. H2-TPR results confirmed that Cu species located on the surface are reduced at a lower temperature while those from the interlayer occur at higher temperature ranges. The photocatalytic degradation of phenol under simulated solar irradiation was used as a model reaction to assess the performances of the studied catalysts. Increased photocatalytic activity was observed for Cu-modified layered perovskites compared to RbLaTa2O7 pristine. This behavior resulted from the efficient separation of photogenerated charge carriers and light absorption induced by copper spacer insertion.

Reusable citric acid modified V/AC catalyst prepared by dielectric barrier discharge for hydroxylation of benzene to phenol

A reusable and efficient citric acid modified V/AC catalyst for benzene hydroxylation was prepared using an environmentally benign DBD method.

Dopamine-modified poly(styrene) nanospheres as new high-speed adsorbents for copper-ions having enhanced smoke-toxicity-suppression and flame-retardancy

Polydopamine-coated polystyrene (PS@PDA) nanospheres which are prepared by self-polymerizing of dopamine on the surfaces of polystyrene (PS) nanospheres show excellent Cu²⁺ adsorption capacity. The Cu²⁺ adsorption capacity of PS@PDA can even reach 178 mg/g in about 6 min, which is superior to the other adsorption materials reported in literatures. Through linear fitting, it can be seen that Cu²⁺ is chemisorption covered by multilayers on the surface of PS@PDA, with less affect by temperature. The PS@PDA nanosphere with good adsorption capacity is first applied as the Cu²⁺ adsorbent and then recycled to preparation of PS nanocomposite with enhanced flame retardancy, great smoke and toxic gases suppression properties. To overcome the drawbacks of evaluation methods reported before, a new evaluation system of analytic hierarchy process is first applied to comprehensively analyze fire safety of samples. The average value of smoke production rate of PS@PDA absorbed 5 mg/L Cu²⁺ (PS 2) reduces by about 10%, and the average and total yield of carbon monoxide of PS 2 decrease by 15.7% and 18.1% compared with that of neat PS, respectively. PS 2 with the highest score of 86.75 has the best comprehensive fire safety performance among all samples. This work provides a guideline for green flame-retardant chemistry.

Preparation of Cu–Cu2O–CuO by solid combustion ignited by dielectric barrier discharge and its activity towards p-nitrophenol reduction

Dielectric barrier discharge induces solid powder combustion at room temperature and atmosphere to prepare a high-activity catalyst for p-nitrophenol reduction.