Large volumes of wastewater from confined pig production are stored in anaerobic lagoons. Control methods are needed to reduce air pollution by foul odors released from these lagoons. In a ...pilot-scale experiment, we evaluated the effect of pig wastewater pre-treatment on reducing the concentration of selected malodor compounds in lagoons receiving liquid from: (1) flocculant enhanced solid-liquid separation (SS), and (2) solid-liquid separation plus biological N treatment using nitrification-denitrification (SS+NDN). A conventional anaerobic lagoon was included as a control. Concentrations of five selected malodorous compounds (phenol, p-cresol, 4-ethylphenol, indole, and skatole) and water quality parameters (ammonia-nitrogen and chemical oxygen demand) were determined in lagoon effluents. The SS+NDN pretreatment was more efficient than the SS in reducing odorous compounds in the lagoon liquid. The SS+NDN reduced by about 99% the liquid concentrations of all selected compounds. An odor panel test revealed that SS was ineffective to reduce the human sense of malodor with respect to the control. Whereas the SS+NDN had the significant lowest odor intensity and unpleasantness. These results are supported by the strong correlations found between the sum of odorous compound concentration with odor panel results and concentrations of both ammonium-nitrogen and chemical oxygen demand in lagoon liquid samples.
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•Alkylation of p-cresol using Bronsted acidic ionic liquids as catalyst.•Mechanistic insights including the effect of solvents.•Higher selectivity to ether product at shorter reaction ...time.•Theoretical studies to correlate acidity and catalytic activity of the catalysts.•Estimation of charge distribution and superdelocalizability to correlate reactivity.
In this work, a combination of density functional theory (DFT) and ab initio methods were used to develop a molecular level understanding of the alkylation of p-cresol with tert-butyl alcohol using Bronsted acidic ionic liquids (ILs) as catalysts. Commonly used triethylammonium based Bronsted acidic ILs were synthesized and their catalytic activity in the alkylation of p-cresol were investigated. Theoretical molecular simulation mimicking the experimental conditions was used to explain the conversion of p-cresol and selectivity to the alkylated products. The experimentally obtained product selectivity was correlated with the theoretically calculated atom reactivity based on superdelocalizabality parameter and the charge distribution. Effect of these parameters in the neutral as well as ionic pathway mechanism in presence of ionic liquid and water solvent mixture were investigated. The mechanism is confirmed from thermochemical energy values that the direct O-alkylation leading to the kinetically controlled ether product predominates at lower temperature (343K) and shorter reaction time. Whereas, the thermodynamically controlled ortho C-alkylated product, 2-TBC, predominates at higher temperature and longer reaction time. Solvent was also found to affect the product selectivity either at the C- or O- sites. With the formation of water as a side product in the course of the alkylation reaction, the dielectric constant of the reaction media increased. Hence, rearrangement of the tert-butyl carbocation in O-alkylated product in presence of the combined IL and water media leads to the formation of C-alkylated products.
This study investigated the inhibitory effects of adsorption treatment on the degradation of oil–paper insulation and corrosive sulphur in oil. A thermal ageing experiment at 130°C was conducted ...using five different adsorbents to adsorb some impurities in oil on the 15th day of a 30 day ageing test, the related characteristics of oil–paper insulation before and after the adsorption treatment were measured and analysed. Meanwhile, a thermal ageing experiment at 150°C was also conducted before using five different adsorbents to adsorb dibenzyl disulphide (DBDS) in oil, energy dispersive X-ray was used to evaluate the degree of the corrosion of windings. The result indicates that adsorption treatment is an effective method to inhibit the degradation of oil–paper insulation. A molecular sieve, silica gel and activated alumina can effectively improve the performance of oil–paper insulation. By contrast, the antioxidant (2, 6-di-tert-butyl-p-cresol) can be also adsorbed by adsorbents, which accelerate the ageing degradation of the insulating oil. On the other hand, the adsorbents can adsorb DBDS in oil, but cannot remove all DBDS. The effect achieved from silica gel is especially significant, which not only effectively improves the performance of oil–paper insulation but also adsorbs DBDS in oil.
Combined anaerobic digestion (AD) and photodegradation of slaughterhouse wastewater (SWW) was carried out to remove biodegradable chemical oxygen demand (COD) and biorecalcitrant aromatic compounds ...which were mainly p-cresol and dibutyl phthalate (DBP). The synergy between the two processes was analyzed through biodegradability enhancement by photodegradation and supply of bioenergy through AD to supplement the energy requirement of the photodegradation process. Degradation products of each process were determined using gas chromatography coupled with a mass spectrometer (GC–MS). Anaerobic digestion as a stand-alone process removed up to 80% COD, while it could only remove about 35% of the aromatic compounds. Photodegradation, as a post-treatment to the AD, removed 92% of the aromatic compounds and enhanced the biodegradability of the digester effluent by 50%, which could be recycled to the AD unit. The aromatic compounds were photodegraded via phthalic acid and hydroquinone. Also, AD as an initial step removed fats, oils, and grease which otherwise would have hindered catalytic activity during photodegradation post-treatment. The biomethane produced could supplement up to 20% of the electricity requirement by the energy-intensive photodegradation process to achieve total pollutants removal, making the integrated process to be a viable option for SWW management.
Food can sometimes contain odors not normally associated with that food. These odors are called off-flavors, and cow milk is known to contain off-flavors such as hexanal depending on the feed or ...physical condition of the cows. We previously discovered and revealed the structure of 2-Iodo-4-methylphenol (2I4MP), an off-flavor component in commercially available cow milk. We were the first group to discover 2I4MP is an off-flavor component in cow milk.This study investigated the following three questions. First, what compounds serve as the starting materials in generating 2I4MP? Organic synthesis techniques were used to identify p-cresol as a candidate starting material. Second, how is 2I4MP generated in the cowshed? Using cow dung, we confirmed that 2I4MP was generated by the effects of iodine on cow dung. Based on these findings, measures were proposed to prevent contamination of cow milk by 2I4MP. Third, how is 2I4MP transferred to raw milk? 2I4MP movement was estimated by creating a desiccator-based model that showed 2I4MP is potentially transferred to raw milk in the cowshed. These involve that the iodine-based disinfectants, used to disinfect teats during milking, should not be used excessively. Furthermore, ensuring the disinfectants do not fall onto cow dung or bedding. Adopting these measures is vital for preventing contamination of cow milk by 2I4MP.
Manure storage contributes significantly to greenhouse gas (GHG), NH
3
and odour emissions from intensive livestock production. A pilot-scale facility with eight 6.5-m
3
slurry storage units was used ...to quantify emissions of CH
4
, N
2
O, NH
3
, and odorants from pig slurry during winter and summer storage. Pig slurry was stored with or without a straw crust, and with or without interception of precipitation, i.e., four treatments, in two randomized blocks. Emissions of total reduced S (mainly H
2
S) and
p
-cresol, but not skatole, were reduced by the straw crust. Total GHG emissions were 0.01–0.02 kg CO
2
eq m
−3
day
−1
during a 45-day winter storage, and 1.1–1.3 kg CO
2
eq m
−3
day
−1
during a 58-day summer storage period independent of storage conditions; the GHG balance was dominated by CH
4
emissions. Nitrous oxide emissions occurred only during summer storage where, apparently, emissions were related to the water balance of the surface crust. An N
2
O emission factor for slurry storage with a straw crust was estimated at 0.002–0.004. There was no evidence for a reduction of CH
4
emissions with a crust. Current Intergovernmental Panel on Climate Change recommendations for N
2
O and CH
4
emission factors are discussed.
An on-line flow injection spectrofluorimetric method for the direct determination of aluminium in water samples is described. The method is based on the reaction of aluminium with
N-
...o-vanillidine–2-amino-
p-cresol (OVAC) in acidic medium at pH 4.0 to form a water-soluble complex. The excitation and emission wavelengths were 423.0 and 553.0
nm, respectively, at which the OVAC–Al complex gave the maximum fluorescence intensity at pH 4.0 in a 50% methanol–50% water medium at 50
°C. An interference from fluoride ions was minimised by the addition of Be
2+. Other ions were found not to interfere at the concentrations likely to be found in natural waters. The proposed methods were validated in terms of linearity, repeatability, detection limit, accuracy and selectivity. Under these conditions, the calibration was linear up to 1000
μg
L
−1 (
r
=
0.999). The limit of detection (3
σ) for the determination of Al(III) was 0.057
μg
L
−1 and the precision for multiple determinations of 3
ng
mL
−1 Al(III) prepared in ultra-pure water was found to be 0.62% (
n
=
10).
The Schiff base ligand could be used to determine ultra-trace aluminium from natural waters. Analysis of environmental certified reference materials showed good agreement with the certified values. The procedure was found to be equally applicable to both freshwater and saline solutions, including seawater.
Stable flies (Stomoxys calcitrans Diptera: Muscidae L.) are blood-feeding synanthropic pests, which cause significant economic losses in livestock. Stable fly antennae contain olfactory sensilla ...responsive to host and host environment-associated odours. Field observation indicated that the abundance of stable flies increased significantly in grasslands or crop fields when cattle manure slurry was applied. Major volatile compounds emanating from manure slurry were collected and identified. Behavioural responses of stable flies to those compounds were investigated in laboratory bioassays and field-trapping studies. Results from olfactometer assays revealed that phenol, p-cresol and m-cresol were attractive to adult stable flies. When tested individually, attraction was higher with lower dosages. Stable flies were most attracted to blends of phenol and m-cresol or p-cresol. Traps with binary blend lures caught more stable flies in field trials as well.
Cardiovascular disease is the leading cause of mortality in hemodialysis patients and is associated with chronic inflammation. Elevation of uremic toxins, particular protein-bound uremic toxins, is a ...possible cause of hyper-inflammation in hemodialysis patients. But the association between uremic toxins and inflammatory markers in hemodialysis is still unclear.
We conducted a cross-sectional study to evaluate the association of the serum uremic toxins and inflammatory markers in hemodialysis patients.
The uremic toxins were not associated with inflammatory markers--including high sensitivity C-reactive protein, IL(Interleukin) -1β, IL-6, tumor necrosis factor-α. In multiple linear regression, serum levels of total p-cresol sulfate (PCS) were independently significantly associated with serum total indoxyl sulfate (IS) (standardized coefficient: 0.274, p<0.001), and co-morbidity of diabetes mellitus (DM) (standardized coefficient: 0.342, p<0.001) and coronary artery disease (CAD) (standardized coefficient: 0.128, p = 0.043). The serum total PCS levels in hemodialysis with co-morbidity of DM and CAD were significantly higher than those without co-morbidity of DM and CAD (34.10±23.44 vs. 16.36±13.06 mg/L, p<0.001). Serum levels of total IS was independently significantly associated with serum creatinine (standardized coefficient: 0.285, p<0.001), total PCS (standardized coefficient: 0.239, p = 0.001), and synthetic membrane dialysis (standardized coefficient: 0.139, p = 0.046).
The study showed that serum levels of total PCS and IS were not associated with pro-inflammatory markers in hemodialysis patients. Besides, serum levels of total PCS were independently positively significantly associated with co-morbidity of CAD and DM.
Mislocalization and abnormal expression of N-methyl-D-aspartate glutamate receptor (NMDAR) subunits is observed in several brain disorders and pathological conditions. Recently, we have shown that ...intraperitoneal injection of the gut neurotoxin p-cresol induces autism-like behavior and accelerates seizure reactions in healthy and epilepsy-prone rats, respectively. In this study, we evaluated the expression of GLUN2B and GLUN2A NMDAR subunits, and assessed the activity of cAMP-response element binding protein (CREB) and Rac1 in the hippocampi and nucleus accumbens of healthy and epilepsy-prone rats following p-cresol administration. We have found that subchronic intraperitoneal injection of p-cresol induced differential expression of GLUN2B and GLUN2A between the two brain regions, and altered the GLUN2B/GLUN2A ratio, in rats in both groups. Moreover, p-cresol impaired CREB phosphorylation in both brain structures and stimulated Rac activity in the hippocampus. These data indicate that p-cresol differently modulates the expression of NMDAR subunits in the nucleus accumbens and hippocampi of healthy and epilepsy-prone rats. We propose that these differences are due to the specificity of interactions between dopaminergic and glutamatergic pathways in these structures.
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