Formation of oil-particle aggregates with motor oil and kaolinite clay in cold and warm freshwater.

Motor oil is one of the most common pollutants in stormwater runoff in freshwater ecosystems. It can form aggregates with solids (creating oil particle aggregates, OPAs) which complicates the understanding of the fate and transport of motor oil, particularly in cold freshwater, conditions that have not been studied extensively. Laboratory and numerical experiments were conducted with kaolinite clay and three types of motor oil in both cold and warm freshwater, in which: (1) the interaction of clay particles with motor oil was experimentally investigated, in response to changes in oil viscosity, water temperature, and mixing intensity; (2) variability in particle size distribution of the formed OPAs was measured; and (3) a mechanistic OPA formation model was applied and results were compared with experimental data. The results showed that kaolinite clay and motor oil formed mostly droplet-type OPAs, lower-viscosity oil tended to form a wider size range of OPAs, and higher mixing intensity and higher water temperature produced larger numbers of smaller OPAs. Although there was a reasonably good match between the experimental data and the modeling results, more research is needed to further improve the modeling framework.

The elimination and extraction of organosulfur compounds from real water and soil samples using metal organic framework/graphene oxide as a novel and efficient nanocomposite.

In the present work, an efficient metal organic framework/graphene oxide (MOF-801/GO) sorbent was fabricated and employed for the detection of organosulfur pesticides (OSPs) in real samples using gas chromatography-flame photometric detection (GC-FPD). The optimal extraction parameters for the suggested solid-phase extraction (SPE) include sorbent amount (60 mg), extraction solvent (acetonitrile) and extraction time (5 min). The linear dynamic ranges and detection limits for organosulfur pesticides (OSPs) samples under above extraction conditions were ranged from 0.5 to 300 µg L-1 and 0.1-1.1 µg L-1, respectively. Moreover, the proposed SPE/GC-FDP method was applied for the analysis of pesticides in different real environmental water and soil samples. The obtained recoveries of the analytes in were between 92.0 and 106.8% and relative standard deviation (RSD) values were lower than 9.2%. The application of the MOF-801/GO as a sorbent in dSPE of OSPs analytes showed to be reliable, fast and sensible methodology for pesticides monitoring in different environmental samples.

Highly reusable bentonite clay@biochar@Fe3O4 nanocomposite for Hg(II) removal from synthetic and real wastewater.

The present research investigates the performance of bentonite clay@biochar@Fe3O4 nanocomposite in removing mercury ions (Hg2+) from aqueous media. The physical and structural properties of bentonite clay@biochar@Fe3O4 were determined using Brunauer-Emmett-Teller (BET), vibrating-sample magnetometer (VSM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and Raman analyses. The highest uptake efficiency of Hg2+ was obtained at pH 6, Hg2+ concentration of 10 mg/L, contact time of 80 min, and the composite dose of 1.5 g/L. Under these conditions, the uptake efficiency of bentonite clay@biochar@Fe3O4 and bentonite clay was obtained as 98.78% and 97.67%, respectively, which are remarkable values. Also, the qmax values in Hg2+ removal using bentonite clay@biochar@Fe3O4 and bentonite clay were obtained as 66.66 and 60.98 mg/g, respectively. Moreover, the uptake process of Hg2+ ions using bentonite clay@biochar@Fe3O4 nanocomposite and bentonite was spontaneous, physical, favorable, and exothermic. Besides, the impact of various divalent ions such as Co2+, Cu2+, Pb2+, Ni2+, and Zn2+ on the removal efficiency of Hg2+ was studied. The results showed that Co2+ and Zn2+ ions have the highest and lowest interference effect in Hg2+ removal, respectively. Also, the reusability of both adsorbents showed that they have high stability and can be used for at least 5 cycles with high uptake efficiency. Additionally, the removal efficiency of chemical oxygen demand (COD), biochemical oxygen demand (BOD5), Hg2+, As3+, and As5+ from real wastewater using bentonite clay@biochar@Fe3O4 was obtained as 37.5%, 28.9%, 65%, 60.5%, and 50%, respectively, indicating its remarkable performance.

Reduction in environmental CO2 by utilization of optimized energy scheme for power and fresh water generations based on different uses of biomass energy.

Renewable energy sources are undoubtedly necessary, considering global electricity demand is expected to rise dramatically in the coming years. This research looks at a unique multi-generation plant from the perspectives of exergy, energy, and economics; also, an environmental evaluation is performed to estimate the systems' CO2 emissions. The unit is made up of a biomass digester and gasifier, a Multi effect Desalination unit, and a supercritical CO2 (SCO2) cycle. In this study, two methods for using biomass are considered: the first is using synthesis gas generated by the gasifier, and the second is utilizing a digester to generate biogas. A comprehensive parametric study is performed on the designed energy unit to assess the influence of compressor pressure ratio, Gas turbine inlet temperature, supercritical CO2 cycle pressure ratio, and the number of effects of multi-effect distillation on the system performance. Furthermore, the exergy study revealed that the exergy destruction in the digestion unit was 11,337 kW, which was greater than the exergy destruction in the gasification unit, which was 9629. Finally, when compared to the gasifier, the amount of exergy efficiency, net output power, and freshwater production in the digester was greater.

Hydroxyapatite@Mn-Fe composite as a reusable sorbent for removal of Nile blue dye and Cr(VI) from polluted water.

In this study, hydroxyapatite@Mn-Fe composite was used as a novel adsorbent to eliminate Nile blue (NB) dye and hexavalent chromium ion (Cr(VI)) from aqueous media. Different analyses such as FTIR, Map, SEM, EDX, BET, and XRD were used to study the characteristics of the composite. The highest sorption efficiencies of Cr(VI) and NB at pH 2 and 10 were 97.63% and 98.83%, respectively, which are significant values. Equilibrium and kinetic studies of the sorption process showed that the Freundlich isotherm model and pseudo-second-order kinetic model can better describe the equilibrium and kinetic behavior of the sorption process. According to the Langmuir model, the maximum sorption capacities of NB dye and Cr(VI) ion using the hydroxyapatite@Mn-Fe composite were 0.259 and 0.938 mmol/g, respectively. Also, the results of the thermodynamic study showed that the sorption process is favorable (ΔS° = - 34.2 kJ/mol·K for Cr(VI) and - 144.6 kJ/mol·K for NB), spontaneous (ΔG° < 0), and exothermic (ΔH° = - 27.99 kJ/mol for Cr(VI) and - 64.2 kJ/mol for NB). Moreover, the desorption process of both contaminants using the hydroxyapatite@Mn-Fe composite showed that the H2SO4 solution with a concentration of 3 mol/L can remove both contaminants separately with the highest efficiency. Furthermore, the reusability study indicated that the composite can be used in five reuse cycles without significant decrease in its efficiency. Besides, the composite was able to eliminate color, turbidity, COD, and BOD5 from the textile wastewater with removal efficiencies of 93.06, 81.61, 76.05, and 71.88%, respectively. To the best of our knowledge, hydroxyapatite@Mn-Fe composite was synthesized and used for the first time to remove Cr(VI) ions and NB dye. In general, the aforementioned composite is recommended for industrial wastewater treatment.

Resolution of conflict of reduced sludge production with EBPR by coupling OSA to A2/O process in a pilot scale SBR.

The pinnacle of all the efforts of nutrient removal is practically put-down the moment biological cells are lysed, hydrolyzed or digested causing subsequent reappearance of assimilated nitrogen and phosphorus in any biological process. While sludge reduction requires high SRT, the enhanced phosphorus assimilative uptake demands low SRT. A novel reactor configuration for enhanced sludge and phosphorus removal was put to test by incorporating a side stream anaerobic reactor to an Anaerobic-Anoxic-Aerobic (A2O) SBR with a pre-anoxic chamber and an influent receiving inlet anaerobic reactor. The reactor was operated at the average and lowest range of prevailing carbon/phosphorus (C/P) ratio of 50 and 15 in the sewage. The phosphorus enrichment was 0.0469-0.135 mgTP/mgVSS resulting in 1.76-5.05-fold increase from cellular content by virtue of maintaining sludge recycle from SBR aeration tank to side stream anaerobic reactor from 3.78 to 9.78 (average 4.4-8.2) gVSS/gVSS present in the reactor. However, the sludge was also reduced from 3% to 51% on an average basis during the same recirculation regime. This novel configuration consists of an inlet anaerobic reactor, one pre-anoxic chamber and one intermittent oxic anoxic reaction SBR and a side stream anaerobic reactor. The first anaerobic reactor at inlet followed by pre-anoxic chamber was provided for increased ortho-p released and nitrification respectively and a side stream anaerobic reactor for sludge reduction through sludge fasting mechanism. The EBPR and lesser sludge growth were two conflicting parameters reconciled to the extent that if sludge recycled up to 6.41 gVSS/gVSS the sludge growth would be reduced by 25% and phosphorus enrichment could be attained up to 3.46 times the stoichiometric value. Any further recirculation would reduce the sludge further but at the expense of enhanced phosphorus uptake as released phosphorus from side stream anaerobic reactor also recycled back to main SBR causing looping and at more than 6.41gVSSrecycled/gVSS it nullified the enhanced effect.

Phenol adsorption and desorption with physically and chemically tailored porous polymers: Mechanistic variability associated with hyper-cross-linking and amination.

Understanding phenol adsorption-desorption mechanisms allows adsorbent tailoring to improve capacity and adsorbent reuse. Amberlite™ XAD4, a commercial styrenic polymer that is convenient to physically and chemically modify, was functionalized with dimethylamine (DMA) or trimethylamine (TMA) and/or hyper-cross-linked with 1,2-dichloroethane. These modifications were applied to enhance individual and/or synergistic phenol adsorption mechanisms, including hydrogen bonding, electrostatic interactions, and π-π dispersion forces. While XAD4-DMA adsorbs more phenol at pH = 6, XAD4-TMA has 23% higher capacity at pH = 11 due to adsorbate deprotonation that increases electrostatic interactions. Combining hyper-cross-linking with amination maximizes adsorption capacity due to synergistic impacts associated with increased micropore volume and surface affinity. Amine groups reduce desorption efficiency by 6-94% due to stronger adsorbate-adsorbent interactions compared to π-π dispersion forces. Isobutanol, which forms hydrogen bonds, is the most efficient desorption solvent, followed by chloroform, which has the same polarity index but does not hydrogen bond. n-Hexane only desorbs phenol removed with π-π dispersion forces and is not appropriate to regenerate aminated polymers. 0.1 N NaOH is an environmentally benign solvent for regenerating as-received XAD4 and XAD4-DMA, but not XAD4-TMA. Understanding phenol adsorption mechanisms allows development of physiochemically modified polymers with increased phenol adsorption capacity and regeneration efficiency.