Electrogenerated oxychlorides induced overlooked negative effects on electro-oxidation wastewater treatment in terms of over-evaluated COD removal efficiency and biotoxicity.

The high-efficiency and environmentally-friendly electro-oxidation (EO) would lose its competitive edge because of the production of oxychloride by-products (ClOx-), which has not yet drawn significant attention in academic and engineering communities. In this study, the negative effects of the electrogenerated ClOx- were compared among four commonly used anode materials (BDD, Ti4O7, PbO2 and Ru-IrO2) in terms of ClOx- interference on the evaluation of electrochemical COD removal performance and biotoxicity. Apparently, the COD removal performance of various EO systems were highly enhanced with increasing current density in the presence of Cl-, e.g., the amounts of COD removed by various EO systems from the phenol solution with an initial COD content of 280 mg L-1 at 40 mA cm-2 within 120 min decreased in the order: Ti4O7 of 265 mg L-1 > BDD of 257 mg L-1 > PbO2 of 202 mg L-1 > Ru-IrO2 of 118 mg L-1, which was different from the case with the absence of Cl- (BDD of 200 mg L-1 > Ti4O7 of 112 mg L-1 > PbO2 of 108 mg L-1 > Ru-IrO2 of 80 mg L-1) and the results after removing ClOx- by anoxic sulfite-based method (BDD of 205 mg L-1 > Ti4O7 of 160 mg L-1 > PbO2 of 153 mg L-1 > Ru-IrO2 of 99 mg L-1). These results can be ascribed to the ClOx- interference on COD evaluation, the extent of which decreased in the order: ClO3- > ClO- (where ClO4- cannot impact COD test). The highest overrated electrochemical COD removal performance of Ti4O7 may be associated with its relatively high production of ClO3- and the low mineralization extent. The chlorella inhibition ratio of ClOx- decreased in the order: ClO- > ClO3- >> ClO4-, which accounted for the biotoxicity increasement of the treated water (PbO2 68%, Ti4O7 56%, BDD 53%, Ru-IrO2 25%). Generally, the inevitable problems of overrated electrochemical COD removal performance and biotoxicity increasement induced by ClOx- should deserve significant attention and effective countermeasures should be also developed when employing EO process for wastewater treatment.

Di-n-butyl phthalate stress hampers compost multifunctionality by reducing microbial biomass, diversity and network complexity.

Phthalates are common pollutants in agriculture. Here, the influence of di-n-butyl phthalate (DBP) on multifunctionality of composting was assessed. Results indicated that DBP stress (100 mg/kg) hampered multifunctionality from the thermophilic phase onwards and resulted in a 6.5 % reduction of all assessed functions. DBP stress also significantly reduced microbial biomass (P < 0.05), altered microbial composition (P < 0.05), and decreased network complexity (P < 0.01). Multifunctionality was found to be strongly correlated (P < 0.001) with microbial biomass, diversity, and network complexity. In addition, keystone taxa responsive to DBP were identified as Streptomyces, Thermoactinomyces, Mycothermus, and Lutispora. These taxa were significantly (P < 0.001) affected by DBP stress, and a correlation between them and multifunctionality was shown. This study contributes to a better understanding of the negative implications of phthalates during composting processes, which is of great significance to the development of new treatment strategies for agricultural waste.

Synergistic Cr(VI) Reduction and Chloramphenicol Degradation by the Visible-Light-Induced Photocatalysis of CuInS2: Performance and Reaction Mechanism.

Despite significant scientific efforts in the field of water treatment, pollution of drinking water by toxic metal ions and synthetic organic compounds is becoming an increasing problem. The photocatalytic capabilities of CuInS2 nanoparticles were examined in this study for both the degradation of chloramphenicol (CAP) and the reduction of Cr(VI). CuInS2 nanoparticles were produced using a straightforward solvothermal approach and subsequently characterized by many analysis techniques. Simultaneous photocatalytic Cr(VI) reduction and CAP oxidation by the CuInS2 nanoparticles under visible-light demonstrated that lower pH and sufficient dissolved oxygen favored both Cr(VI) reduction and CAP oxidation. On the basis of active species quenching experiments, the possible photocatalytic mechanisms for Cr(VI) conversion with synchronous CAP degradation were proposed. Additionally, the CuInS2 retains a high rate of mixed pollutant removal after five runs. This work shows that organic contaminants and heavy metal ions can be treated concurrently by the visible-light-induced photocatalysis of CuInS2.

Efficient simultaneous removal of tetracycline hydrochloride and Cr(VI) through photothermal-assisted photocatalytic-Fenton-like processes with CuOx/γ-Al2O3.

Advanced oxidation processes (AOPs) based on photo-Fenton reaction has been widely used in refractory organic wastewater treatment. However, the mineralization rate and H2O2 utilization in AOPs is relatively low. Herein, a photothermal-assisted photocatalytic-Fenton-like process with CuOx/γ-Al2O3 catalyst was designed to solve the above issues. The utilization rate of H2O2 and mineralization rate of tetracycline hydrochloride (TC) in the 3%-CuOx/γ-Al2O3/H2O2/full spectrum light system were significantly increased to 72.0% and 74.3%, respectively, which were ascribed to the synergy of photothermal effect and photocatalytic-Fenton-like reaction. During the simultaneous removal of TC and Cr(VI), the reaction efficiency of 3%-CuOx/γ-Al2O3/H2O2/light system was much higher than that of 3%-CuOx/γ-Al2O3/H2O2 system. In addition, the 3%-CuOx/γ-Al2O3/H2O2/light system was not only active in wider pH range (3-9), but also effective in various organic pollutants and Cr(VI) coexisted solutions as well as different water conditions. More importantly, a possible photothermal-assisted photocatalytic-Fenton-like reaction mechanism for the simultaneous removal of TC and Cr(VI) in the CuOx/γ-Al2O3/H2O2/light system was proposed. This work may pave a new way for efficient simultaneous removal of refractory organic pollutants and heavy metals in wastewater.

Ultrasonic-Assisted Synthesis of CdS/Microcrystalline Cellulose Nanocomposites With Enhanced Visible-Light-Driven Photocatalytic Degradation of MB and the Corresponding Mechanism Study.

A simple and efficient ultrasonic-assisted approach was designed to synthesize CdS/microcrystalline cellulose (MCC) nanocomposite photocatalyst. The obtained products have been characterized by XRD, FE-SEM, TEM, UV-Vis DRS, and nitrogen adsorption isotherms. The results showed that the intimate contact of MCC and CdS is beneficial for enhancing the photocatalytic performance because heterojunction formation can efficiently promote the separation of photogenerated electrons and holes of the nanocomposite photocatalyst. By using 10% MCC coupled CdS, the decoloration rate of methylene blue (MB) in the solution under visible-light was increased nearly 50%. In addition, the reuse experiments confirmed that the CdS/MCC nanocomposite photocatalyst had outstanding cycle performance and durability. Mechanism study demonstrated that hydroxyl radicals, photogenerated holes and superoxide radicals were the active species in the photocatalytic oxidization degradation of MB.

The study of hydrothermal liquefaction of corn straw with Nano ferrite + inorganic base catalyst system at low temperature.

Hydrothermal liquefaction of corn straw with different catalytic systems and temperatures were investigated in this study. Results showed dual catalytic system can effectively promote the degradation of corn straw at low temperature. With increase of temperature, aqueous phase increased and straw residue decreased for all catalytic systems. The heavy bio-oil yield increased with the increasing of temperature for single catalytic system, while the trend was opposite for dual catalytic system. In single catalytic system, ZnFe2O4 was more suitable for preparation of heavy bio-oil, and the maximum yield reached 34.02 wt% at 180 °C. The proportion of monophenyl compounds in heavy bio-oil for dual catalytic system reached the maximum of 84% at 220 °C with ZnFe2O4. At 180 °C, the contents of Benzofuran,2,3-dihydro and 2-Methoxy-4-vinylphenol reached the maximum of 31.42% and 17.64% in CoFe2O4 catalyst system, and the maximum yield of Vanillin was 10.82% with ZnFe2O4.

Catalytic hydrothermal liquefaction of Gracilaria corticata macroalgae: Effects of process parameter on bio-oil up-gradation.

Hydrothermal liquefaction (HTL) of Gracilaria corticata (GC) macroalgae was studied over a series of nickel-iron-layered double oxides (NiFe-LDO) supported on activated bio-char catalysts at 280 °C and different solvents medium. Maximum bio-oil yield (56.2 wt%) was found with 5%Ga/NiFe-LDO/AC catalyst at 280 °C under ethanol solvent. The catalytic HTL up-gradation decreased the bio-char yield significantly. However the bio-oil quality significantly improved with using the 5%Ga/NiFe-LDO/AC catalyst. Also, improved performance with higher amount of bio-oil and lower amounts of bio-char and gas were achieved, which is due the several reactions happening during the HTL process. Catalytic HTL also revealed that introducing NiFe-LDO nanosheets into the activated char could result in NiFe-LDO/AC catalysts of higher surface area and increased active sites. Being impregnated by 5%Ga, catalysts with improved acid sites and thereby, advanced deoxygenation and aromatization activities were achieved. Hence Ga/NiFe-LDO/AC could be considered as a promising catalyst HTL bio-oil upgrading.

Spatial distribution, risk assessment and influence factors of terrestrial gamma radiation dose in China.

The current spatial distribution of the risk of terrestrial gamma radiation in China were investigated by using spatial interpolation. And the driving factors influence on the terrestrial gamma radiation dose (TGRD) distribution were identified using the geographic detector, a new statistical method based on the nonlinear hypothesis. The results showed that the values of TGRD were range from 60 to 195 nGy h-1 with the average of 86.5 nGy h-1, and the higher values were recorded in Qingahi-Tibet Plateau, which were all within the range of background value in China. In addition, the radiological indices, ELCR (Excess Lifetime Cancer Risk), TGRD and AEDE (Annual Effective Dose Equivalent) were also within the acceptable range of values by risk assessment. The results by use of the geographic detector showed that sunshine duration, atmosphere pressure, altitude, and rainfall condition have closely related to the TGRD distribution. In addition, these meteorological factors and altitude had more impact on TGRD than the air pollution-related factors. Our study can provide useful information on studying the influence mechanism of the TGRD distribution, the variability of the natural terrestrial gamma radiation in China, and exposure data for risk assessment from low dose chronic exposures.

Hydrothermal liquefaction of corn straw with mixed catalysts for the production of bio-oil and aromatic compounds.

In this study, hydrothermal liquefaction (HTL) of corn straw at different operation temperatures, reaction time and catalyst dosage were investigated, and the main product was heavy bio-oil. Results showed that CuO + NaOH have a synergistic effect in the HTL of corn straw. The product distribution and composition were also studied during the process, in which aromatic compounds achieved the highest proportion in heavy bio-oil. Moreover, the yield of aromatic compounds in hydrothermal products increased under simultaneous action of homogeneous and heterogeneous catalysts. The maximum ratio of aromatic compounds was 89.84% under condition of temperature 230 °C, reaction time 1 h, CuO content 3 g and NaOH 100 mL (1 mol·L-1). GC-MS analysis indicated that the major organic compounds in heavy bio-oil at temperatures between 210 °C and 270 °C were interestingly similar. SEM, XRD, H2-TPR and XPS analysis showed that CuO was completely reduced to copper in the process.

Synergistic hydrothermal liquefaction of wheat stalk with homogeneous and heterogeneous catalyst at low temperature.

The effect of Na2CO3, Fe and Na2CO3 + Fe during hydrothermal liquefaction (HTL) of wheat stalk with different temperature and reaction time was investigated in this study. The results indicated that Na2CO3 + Fe can promote the cracking of wheat stalk compared with Na2CO3 or Fe. Meanwhile, higher temperature favored the decomposition of wheat stalk and formation of heavy bio-oil. The highest heavy bio-oil yield was 24.25 wt% and the maximum liquefaction conversion rate was 89.45 wt% in system of Na2CO3 + Fe at 270 °C. The analysis results indicated that longer reaction time could promote liquefaction conversion especially for heavy bio-oil with Na2CO3 + Fe during the process of HTL. GC-MS, UPLC-MS and FT-IR analysis indicated that the major organic compounds in heavy bio-oil were aromatic compounds, alcohols, ketones, alkanes, and aldehydes, among of them aromatic compounds were the most prevalent.

The Enhanced Catalytic Performance and Stability of Rh/γ-Al2O3 Catalyst Synthesized by Atomic Layer Deposition (ALD) for Methane Dry Reforming.

Rh/γ-Al2O3 catalysts were synthesized by both incipient wetness impregnation (IWI) and atomic layer deposition (ALD). The TEM images of the two catalysts showed that the catalyst from ALD had smaller particle size, and narrower size distribution. The surface chemical states of both catalysts were investigated by both XPS and X-ray Absorption Near Edge Structure (XANES), and the catalyst from IWI had higher concentration of Rh3+ than that from ALD. The catalytic performance of both catalysts was tested in the dry reforming of methane reaction. The catalyst from ALD showed a higher conversion and selectivity than that from IWI. The stability testing results indicated that the catalyst from ALD showed similar stability to that from IWI at 500 °C, but higher stability at 800 °C.