车用聚丙烯改性材料气味分析及改善措施

针对改性的聚丙烯(PP)材料,探讨了基体PP树脂、吸附剂、后处理工艺以及加香对PP改性材料气味的影响.研究结果表明,选用氢调法PP树脂制得的PP改性材料气味性能优于降解法;吸附剂能一定程度继续提升PP气味;同时材料的后处理对PP改性材料的气味提升有积极作用;最后通过加香措施对PP改性材料味型进行适当的调整,最终改善后的...     

Removal of unpleasant odor gases using an Ag-Mn catalyst

Conversions of acetaldehyde and trimethylamine as model unpleasant odor gases were measured over several catalysts. The activities of Ag and Mn₂O₃ were the highest of the catalysts that consisted of a single component. The addition of Ag to manganese oxide enhanced the activity and the durability of the catalysts. The activity of Mn catalyst was improved by the addition of Ag up to 40 atom-%, and the maximum activity was observed at 10 atom-%. Acetaldehyde was considered to be decomposed over the AgMn catalyst by oxidation according to the measurement of reaction products. The oxidation state of silver was maintained on the surface of the AgMn catalyst calcined at 773 K. The amount of oxygen adsorbed on the surface of the AgMn catalyst was about 2.9 times as much as that on Mn₂O₃. These experimental data suggested that manganese oxide supplied oxygen to silver and that the oxidation state of silver was maintained on the surface of the AgMn catalyst.     

Effects of periods of starvation and fluctuating hydrogen sulfide concentration on biofilter dynamics and performance

The paper describes the results of a systematic study of the transient behavior of biofilters treating reduced sulfur pulping odors and VOCs. They were exposed to variations in contaminant loading and periods of starvation. Three bench-scale biofilters with different filter media were used. Filter media materials used were the mixtures of compost/perlite (4:1), hog fuel/perlite (4:1), and compost/hog fuel/perlite (2:2:1). Hydrogen sulfide, the main malodorous gas produced from kraft pulping processes, was used as the test contaminant. The starvation period comprised of two stages: the ‘no-contaminant-loading phase' when only humidified air was passing through the biofilters, and the ‘idle phase' when no air was passing through the biofilters. The response of each biofilter to variations in contaminant mass loading was studied by abruptly changing the concentration and/or flow rate of the inlet waste air stream. Contaminant concentration was continuously measured until a new steady state, for each stage, was achieved. Concentration spikes were applied to study the effects of shock loading on the biofilter removal rates. Biofilters responded effectively to H₂S concentration variations and shock loading by rapidly recovering to the original removal rates within 2–8 h. The re-acclimation times to reach full capacity were very short ranging between 15 and 120 h. Extended periods of starvation resulted in longer re-acclimation periods, so does the idle phase as compared to no-contaminant-loading phase.     

Ozonation at Wiggins Water Purification Works,Durban, South Africa

The post-ozone plant at Wiggins waterworks was commissioned during 1984. The main objective of the post–ozone plant was to ensure proper disinfection, including the elimination of viruses, whenever raw water for the works was pumped from the polluted lower Umgeni River. The main problems experienced with the post–ozone plant were poor ozone transfer efficiency in the contact tank and poisoning of the catalyst in the thermal-catalytic destructor.     

Ozonation of swine manure wastes to control odors and reduce the concentrations of pathogens and toxic fermentation metabolites

The use of ozone for the remediation of nuisance odorous chemicals in liquid swine manure slurry was investigated. Gaseous ozone was bubbled directly into stored swine manure slurry in a continuously stirred batch reactor. One‐liter samples of swine slurry were ozonated to achieve ozone dosages of 1.0, 2.0 and 3.0 g ozone/liter of waste. Olfactometric determinations demonstrated a significant reduction in odors in ozonated samples as compared to raw and oxygenated samples. Volatile fatty acids, nitrate, phosphate and ammonia concentrations were unchanged by ozonation. The biochemical oxygen demand (BOD) and the chemical oxygen demand (COD) were essentially unaffected by ozonation. The concentrations of odorous phenolic microbial metabolites (e.g., phenol, p‐cresol and p‐ethylphenol) and odorous indolic microbial metabolites (e.g., 3‐methylindole and indole) were reduced to non‐detectable levels by ozonation. Hydrogen sulfide concentrations were reduced slightly by the process, with a concurrent increase in the sulfate concentration. E. coli counts were reduced by a factor of three log units and total coliforms showed a one log decrease in concentration after treatment with ozone at 1.0 g/L.

The results of this study demonstrate clearly that at the pH values studied (ca. 7), ozonation is effective for the elimination of the malodors associated with stored swine slurry and for killing potentially pathogenic bacteria, without increasing the concentrations of major pollutants of current concern, (i.e., nitrate and phosphate) and without oxidizing ammonia, which is a major plant nutrient.     

Predicting odor mixture's responses on machine olfaction sensors

One of the challenging issues in current research on machine olfaction devices, which are often called electronic noses (e-noses), is how to approximate or predict the sensor response to odor mixtures. When each odor is produced by its own unique set of odorant compounds, combinations of these unique odorant sets create a sensing challenge for the e-noses with a limited number of elements in its sensing array. One possible approach proposed in the literature is based on an “additive law of mixing” model but it fails in a complex odor mixtures. Another method adopted a specific hardware solution called odor recorder developed by using active odor sensing system. In this study, signal decomposition/reconstruction based on wavelet analysis and support vector regression are adopted to predict a sensor's response to mixtures of odors. The prediction results of our method are investigated and compared with the real sensor responses collected from a commercial e-nose machine, the AppliedSensor NST 3320. We find that the proposed method provides good prediction when applied to different mixing ratios of some coffees and green tea.     

Odor and chemesthesis from brief exposures to TXIB

An experiment explored ability of subjects to detect vapors of the plasticizer TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) and ethanol via olfaction and via ocular and nasal chemesthesis, i.e. chemically stimulated feel. Testing, tailored to the sensitivity of each subject, produced psychometric functions for individuals. Olfactory detection of TXIB began at concentrations below 1 ppb (v/v), with 50% correct detection at 1.2 ppb. (Comparable detection for ethanol occurred almost two orders of magnitude higher.) Chemesthetic detection of TXIB began at about 500 ppb, with 50% correct detection at 2.1 ppm for the eye and 4.6 ppm for the nose, both close to saturated vapor concentration. (Comparable detection for ethanol occurred essentially three orders of magnitude higher.) Suggestions that TXIB plays a role in generation of irritative symptoms at concentrations in the range of parts-per-billion need to reckon with a conservatively estimated 200-fold gap between the levels putatively 'responsible' for the symptoms and those even minimally detectable via chemesthesis. Neither the variable of exposure duration nor that of mixing offers a likely explanation. Inclusion of ethanol in the study allowed comparisons pertinent to issues of variability in human chemoreception. An interpretation of the psychometric functions for individuals across materials and perceptual continua led to the conclusion that use of concentration as the metric of detection in olfaction inflates individual differences. PRACTICAL IMPLICATIONS: This study indicated that the plasticizer TXIB could contribute odor at concentrations in the range of parts-per-billion, but could hardly contribute sensory irritation per se, as alleged in reports of some field studies where TXIB has existed amongst many other organic compounds.     

基于PEN3实验数据的嗅觉信息处理算法及应用

不同品质的油桃所散发的气味不同.使用电子鼻采集不同品质的油桃的气味特征参数,在电子鼻软件和MATLAB条件下分别利用偏最小二乘算法判断油桃的品质.结果表明:偏最小二乘法可以较好地鉴别油桃的品质.     

Control of DMSO in wastewater to prevent DMS nuisance odors

A “canned corn-like” odor was periodically detected at Philadelphia's Northeast Water Pollution Control Plant (NEWPCP) for more than two decades. Previous research concluded that it was caused by dimethyl sulfide (DMS), from the reduction of dimethyl sulfoxide (DMSO) discharged by a local industrial customer. Several process modifications were implemented at the industrial site to eliminate the “canned corn-like” odor. Results showed that enhancing DMSO recovery by 25% and equalizing the aqueous wash discharge over a longer period of time reduced the DMSO source peak discharge from 1124 to 49 kg/h, and the peak concentrations of DMSO and DMS at the NEWPCP by 81 and 88%. Reduction of DMSO discharge by segregating the first wash for off-site disposal further reduced the peak discharge of DMSO from 49 to 18 kg/h at the source, and DMSO and DMS concentrations at the NEWPCP by 48 and 92%. Segregation of the dehydration distillate for off-site disposal reduced DMSO discharge by 3 kg/h. Modifications by concentrating a higher percentage of the DMSO into the first wash and increasing the DMSO solvent recovery by an additional 33% reduced the total DMSO discharge from 522 to 200 kg and peak discharge rate from 15 to 6 kg/h. All of these process modifications collectively reduced the DMSO source discharge by 92% and the DMSO concentration received at NEWPCP by 97%, from 12 mg/L to ∼500 μg/L. At this reduced concentration, the company's wastewater discharge was no longer found to cause the “canned corn” odor at the fence line of NEWPCP, thereby mitigating any further need for odor control.     

Static headspace analysis-olfactometry (SHA-O) of odor impact components in salted-dried white herring (Ilisha elongata)

The odorous components of salted-dried white herrings from different treatment conditions were determined by static headspace analysis-olfactometry (SHA-O). Fish samples were purchased from two locations, manufactured by two methods, purchased for two consecutive years, and investigated at two conditions (raw and steamed). Twenty-seven odorous compounds were found among the fish products including alcohols (3), aldehydes (7), miscellaneous compounds (2), ketones (3), other N-containing compounds (4), other O-containing compounds (1), and S-containing compounds (7). Seven potent components including 3-methylbutanal (almond-like), methanethiol (decay vegetable-like), dimethyl trisulfide (fried garlic, onion-like), hydrogen sulfide (rotten egg-like), trimethylamine (fishy, fish oil-like) bis(methylthio)methane (fried garlic/onion-like), and (Z)-4-heptenal (fatty, grease-like) were identified. The majority of them did not have significant difference among the different treatments (p > 0.05). Other less potent components may contribute to the odor of a fish due to their differences in distribution and potency. Statistically, only location and method × period interaction have major impacts on the magnitude of the odorants found in salted-dried white herrings (p < 0.05).