Concept: Hydrogen chloride
Simultaneous removal of nitrate and pentachlorophenol from simulated groundwater using a biodenitrification reactor packed with corncob
- Environmental science and pollution research international
- Published almost 4 years ago
Both nitrate and pentachlorophenol (PCP) are familiar pollutants in aqueous environment. This research is focused on the simultaneous removal of nitrate and PCP from simulated contaminated groundwater using a laboratory-scale denitrification reactor packed with corncob as both carbon source and biofilm support. The reactor could be started up readily, and the removal efficiencies of nitrate and PCP reached up to approximately 98 % and 40-45 % when their initial concentrations were 50 mg N/L and 5 mg/L, respectively, after 15-day continuous operation at 10 h of hydraulic retention time (HRT) and 25 °C. Approximately 91 % of PCP removal efficiency was achieved, with 2.47 mg/L of chloride ion release at 24 h of HRT. Eighty-two percent of chlorine in PCP removed was ionized. The productions of 3-chlorophenol and phenol and chloride ion release indicate that the reductive dechlorination reaction is a major degradation pathway of PCP under the experimental conditions.
The pressure-temperature phase diagram of ice displays a perplexing variety of structurally distinct phases. In the century-long history of scientific research on ice, the proton-ordered ice phases numbered XIII through XV were discovered only recently. Despite considerable effort, none of the transitions leading from the low-temperature ordered ices VIII, IX, XI, XIII, XIV and XV to their high-temperature disordered counterparts were experimentally found to display the full Pauling entropy. Here we report calorimetric measurements on suitably high-pressure-treated, hydrogen chloride-doped ice XIV that demonstrate just this at the transition to ice XII. Dielectric spectroscopy on undoped and on variously doped ice XII crystals reveals that addition of hydrogen chloride, the agent triggering complete proton order in ice XIV, enhances the precursor dynamics strongest. These discoveries provide new insights into the puzzling observation that different dopants trigger the formation of different proton-ordered ice phases.
An unprecedented enantioselective oxetane opening with chloride provides access to a range of highly functionalized three-carbon building blocks. The excellent enantiocontrol is enabled by not only a new catalyst, but also by the unusual use of wet molecular sieves for the controlled release of HCl.
Multiple adsorption and desorption cycles are required to achieve the reliable operation of copper removal and recovery. A green sorption media mixture composed of recycled tire chunk, expanded clay aggregate, and coconut coir was evaluated in this study for its desorptive characteristics as a companion study of the corresponding adsorption process in an earlier publication. We conducted a screening of potential desorbing agents, batch desorption equilibrium and kinetic studies, and batch tests through 3 adsorption/desorption cycles. The desorbing agent screening revealed that hydrochloric acid has good potential for copper desorption. Equilibrium data fit the Freundlich isotherm, whereas kinetic data had high correlation with the Lagergren pseudo second-order model and revealed a rapid desorption reaction. Batch equilibrium data over 3 adsorption/desorption cycles showed that the coconut coir and media mixture were the most resilient, demonstrating they could be used through 3 or more adsorption/desorption cycles. FE-SEM imaging, XRD, and EDS analyses supported the batch adsorption and desorption results showing significant surface sorption of CuO species in the media mixture and coconut coir, followed by partial desorption using 0.1 M HCl as a desorbing agent.
To obtain high-performance adsorbents that combine excellent adsorption ability, thermal stability, service life and recycling ability, polyimide (PI)/silica powders were prepared via a facile one-pot coprecipitation process. A benzimidazole unit was introduced into the PI backbone as the adsorption site. The benzimidazole unit induced more hydroxyls onto the silica, which provided hydrophilic sites for access by heavy metal ions. By comprehensively analyzing the effect of hydrophilcity, agglomeration, silica polycondensation, specific surface area and PI crystallinity, 10% was demonstrated to be the most proper feed silica content. The equilibrium adsorption amount (Qe) for Cu(2+) of PI/silica adsorbents was 77 times higher than that of pure PI. Hydrogen chloride (HCl) was used as a desorbent for heavy metal ions and could be decomplexed with benzimidazole unit at around 300°C, which was lower than the glass transition temperature of PI. The complexation and decomplexation process of HCl made PI/silica adsorbents recyclable, and the adsorption ability remained steady for more than 50 recycling processes. As PI/silica adsorbents possess excellent thermal stability, chemical resistance and radiation resistance and hydrophilicity, they have potential as superior recyclable adsorbents for collecting heavy metal ions from waste water in extreme environments.
Porous titanium scaffolds with injectable hyaluronic acid-DBM gel for bone substitution in a rat critical-sized calvarial defect model
- Journal of tissue engineering and regenerative medicine
- Published about 1 month ago
Demineralized bone matrix (DBM) is an allograft bone substitute used for bone repair surgery to overcome drawbacks of autologous bone grafting, such as limited supply and donor-site comorbidities. In view of different demineralization treatments to obtain DBM, we examined the biological performance of two differently demineralized types of DBM, i.e. by acidic treatment using hydrochloric acid (HCl) or treatment with the chelating agent ethylene diamine tetra-acetate (EDTA). First, we evaluated the osteo-inductive properties of both DBMs by implanting the materials subcutaneously in rats. Second, we evaluated the effects on bone formation by incorporating DBM in a hyaluronic acid (HA) gel to fill a porous titanium scaffold for use in a critical-sized calvarial defect model in 36 male Wistar rats. These porous titanium scaffolds were implanted empty or filled with HA gel containing either DBM HCl or DBM EDTA. Ectopically implanted DBM HCl and DBM EDTA did not induce ectopic bone formation over the course of 12 weeks. For the calvarial defects, mean percentages of newly formed bone at 2 weeks were significantly higher for Ti-Empty compared to Ti-HA + DBM HCl, but not compared to Ti-HA + DBM EDTA. Significant temporal bone formation was observed for Ti-Empty and Ti-HA + DBM HCl, but not for Ti-HA + DBM EDTA. At 8 weeks there were no significant differences in values of bone formation between the three experimental constructs. In conclusion, these results showed that, under the current experimental conditions, neither DBM HCl nor DBM EDTA possess osteo-inductive properties. Additionally, in combination with an HA gel loaded in a porous titanium scaffold, DBM HCl and DBM EDTA showed similar amounts of new bone formation after 8 weeks, which were lower than using the empty porous titanium scaffold. Copyright © 2016 John Wiley & Sons, Ltd.
A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering.
Photochlorination of aromatic substrates by hydrogen chloride with 2,3-dichloro-5,6-cyano-p-benzoquinone (DDQ) occurs efficiently to produce the corresponding monochlorinated products selectively under visible-light irradiation.The yields for the chlorination of phenol were 70% and 18% for p- and o-chlorophenol, respectively, without formation of further chlorinated products. The photoinduced chlorination is initiated by electron transfer from Cl- to the triplet excited state of DDQ. The radical intermediates involved in the photochemical reaction have been detected by the time-resolved transient absorption measurements.
A passive sampler for determining the time-weighted average total ammonia (i.e. molecular ammonia and the ammonium cation) concentration (C TWA) in freshwaters, which incorporated a polymer inclusion membrane (PIM) as a semi-permeable barrier separating the aqueous source solution from the receiving solution (i.e. 0.8 mol L(-1) HCl), was developed for the first time. The PIM was composed of dinonylnaphthalene sulfonic acid (DNNS) as a carrier, poly (vinyl chloride) (PVC) as a base polymer and 1-tetradecanol as a modifier. Its optimal composition was found to be 35 wt% commercial DNNS, 55 wt% PVC and 10 wt% 1-tetradecanol. The effect of environmental variables such as the water matrix, pH and temperature were also studied using synthetic freshwaters. The passive sampler was calibrated under laboratory conditions using synthetic freshwaters and exhibited a linear response within the concentration range 0.59-2.8 mg L(-1) NH4 (+) (0.46-2.1 mg N L(-1)) at 20 °C. The performance of the sampler was further investigated under field conditions over 7 days. A strong correlation between spot sampling and passive sampling was achieved, thus providing a proof-of-concept for the passive sampler for reliably measuring the C TWA of total ammonia in freshwaters, which can be used as an indicator in tracking sources of faecal contamination in stormwater drains. Graphical Abstract Cross section of a passive sampler (amplified membrane thickness) with a schematic representation of the transport mechanism for total ammonia across the dinonylnaphthalene sulfonic acid (DNNS)-based polymer inclusion membrane (PIM). Black solid arrows illustrate the extraction process. Grey solid arrows illustrate the back-extraction process.
Phosphorus (P) leaching characteristics of polyaluminium chlorides (PAC) treated wastewater sludge was investigated by wet chemicals (acid and alkali). Sludge fractionation showed non-apatite inorganic P was the dominant P (90.9% of TP) while apatite P only accounted for 3.7%. After 2h extraction with 1N NaOH or 2N HCl, 80.5% and 77.9% of total P was leached, while sludge dissolution reached 72.7% and 75.6%, respectively. Kinetic study with HCl and NaOH showed that P release and sludge dissolution follow first order reaction with rate constants of 0.50 and 0.35min(-1) (P release) and 0.47×10(-2) and 0.15×10(-2)min(-1) (sludge dissolution), respectively. Sequential extraction by NaOH/HCl leached 91.7% of the total P. This study will help in understanding the P release behavior of the PAC treated wastewater sludge.