Aqueous-phase catalyzed reduction of organic contaminants via zerovalent copper nanoparticles (nC... more Aqueous-phase catalyzed reduction of organic contaminants via zerovalent copper nanoparticles (nCu0), coupled with borohydride (hydrogen donor), has shown promising results. So far, the research on nCu0 as a remedial treatment has focused mainly on contaminant removal efficiencies and degradation mechanisms. Our study has examined the effects of Cu0/Cun+ ratio, surface poisoning (presence of chloride, sulfides, humic acid (HA)), and regeneration of Cu0 sites on catalytic dechlorination of aqueous-phase 1,2-dichloroethane (1,2-DCA) via nCu0-borohydride. Scanning electron microscopy confirmed the nano size and quasi-spherical shape of nCu0 particles. X-ray diffraction confirmed the presence of Cu0 and Cu2O and x-ray photoelectron spectroscopy also provided the Cu0/Cun+ ratios. Reactivity experiments showed that nCu0 was incapable of utilizing H2 from borohydride left over during nCu0 synthesis and, hence, additional borohydride was essential for 1,2-DCA dechlorination. Washing the nCu...
Global research is moving forward in developing hydrogen as a renewable energy source in order to... more Global research is moving forward in developing hydrogen as a renewable energy source in order to alleviate concerns related to carbon dioxide emissions and depleting fossil fuels resources. Biohydrogen has the potential to replace current hydrogen production technologies relying heavily on fossil fuels. Batch and continuous systems employing pure mesophiles and thermophiles isolates and co-cultures of isolates have been investigated. The co-cultures of the isolates achieved better results than mono-cultures of the isolates with respect to different parameters. This paper presents a critical review of the literature reporting on fermentative biohydrogen production by pure cultures of bacteria in different systems. Synergies between different types of bacteria, i.e. strict and facultative, and a comparison between mono- and co-cultures, types of feedstocks, and preferred feedstocks for mono- and cultures are outlined.
1,2-Dichloroethane (1,2-DCA) is among the most frequently detected chlorinated organic compounds ... more 1,2-Dichloroethane (1,2-DCA) is among the most frequently detected chlorinated organic compounds (COCs) at contaminated sites. Possible carcinogenicity and recalcitrance towards abiotic dechlorination has created considerable interest in developing remediation technologies to successfully treat 1,2-DCA. Recently, aqueous-phase catalyzed hydrodechlorination has emerged as a field-applicable technology showing promising results in reducing various COCs. However, there has been limited success in applying this technology to treat 1,2-DCA, even at the bench scale. In the current study, the feasibility of aqueous-phase catalyzed hydrodechlorination of 1,2- DCA was investigated over Pd nanoparticles (nPd) with the residual borohydride from nPd synthesis as a hydrogen (H2) source. nPd particles were synthesized via aqueous chemical reduction by sodium borohydride. Complete removal of 1,2-DCA (32 mg L−1 ) in < 7 days was achieved with both bare and stabilized nPd (1 g L−1 ) particles and the reaction followed pseudo-first-order kinetics. No additional injections of borohydride or any other H2 source were needed. Ethane was the main reaction product indicating hydrogenolysis as the major dechlorination pathway. Different synthesis parameters were found to affect the oxidation state, elemental composition and the catalytic activity of nPd and consequently 1,2-DCA dechlorination. Detailed surface characterization including TEM, SEM/EDX, XPS and XRD of nPd particles was conducted. This study is an initial step to show that even recalcitrant COCs like 1,2-DCA can be successfully treated in the aqueous-phase via nPdborohydride
suspensions, and likely other nanocatalysts, without any external/additional H2 source. However, further research is needed to provide more insight on how to transfer this technology from ideal laboratory conditions to real-field situations. The results also help provide clues on the development of a process level understanding of 1,2 DCA dechlorination via nanocatalysts.
Aqueous-phase catalyzed reduction of organic contaminants via zerovalent copper nanoparticles (nC... more Aqueous-phase catalyzed reduction of organic contaminants via zerovalent copper nanoparticles (nCu0), coupled with borohydride (hydrogen donor), has shown promising results. So far, the research on nCu0 as a remedial treatment has focused mainly on contaminant removal efficiencies and degradation mechanisms. Our study has examined the effects of Cu0/Cun+ ratio, surface poisoning (presence of chloride, sulfides, humic acid (HA)), and regeneration of Cu0 sites on catalytic dechlorination of aqueous-phase 1,2-dichloroethane (1,2-DCA) via nCu0-borohydride. Scanning electron microscopy confirmed the nano size and quasi-spherical shape of nCu0 particles. X-ray diffraction confirmed the presence of Cu0 and Cu2O and x-ray photoelectron spectroscopy also provided the Cu0/Cun+ ratios. Reactivity experiments showed that nCu0 was incapable of utilizing H2 from borohydride left over during nCu0 synthesis and, hence, additional borohydride was essential for 1,2-DCA dechlorination. Washing the nCu...
Global research is moving forward in developing hydrogen as a renewable energy source in order to... more Global research is moving forward in developing hydrogen as a renewable energy source in order to alleviate concerns related to carbon dioxide emissions and depleting fossil fuels resources. Biohydrogen has the potential to replace current hydrogen production technologies relying heavily on fossil fuels. Batch and continuous systems employing pure mesophiles and thermophiles isolates and co-cultures of isolates have been investigated. The co-cultures of the isolates achieved better results than mono-cultures of the isolates with respect to different parameters. This paper presents a critical review of the literature reporting on fermentative biohydrogen production by pure cultures of bacteria in different systems. Synergies between different types of bacteria, i.e. strict and facultative, and a comparison between mono- and co-cultures, types of feedstocks, and preferred feedstocks for mono- and cultures are outlined.
1,2-Dichloroethane (1,2-DCA) is among the most frequently detected chlorinated organic compounds ... more 1,2-Dichloroethane (1,2-DCA) is among the most frequently detected chlorinated organic compounds (COCs) at contaminated sites. Possible carcinogenicity and recalcitrance towards abiotic dechlorination has created considerable interest in developing remediation technologies to successfully treat 1,2-DCA. Recently, aqueous-phase catalyzed hydrodechlorination has emerged as a field-applicable technology showing promising results in reducing various COCs. However, there has been limited success in applying this technology to treat 1,2-DCA, even at the bench scale. In the current study, the feasibility of aqueous-phase catalyzed hydrodechlorination of 1,2- DCA was investigated over Pd nanoparticles (nPd) with the residual borohydride from nPd synthesis as a hydrogen (H2) source. nPd particles were synthesized via aqueous chemical reduction by sodium borohydride. Complete removal of 1,2-DCA (32 mg L−1 ) in < 7 days was achieved with both bare and stabilized nPd (1 g L−1 ) particles and the reaction followed pseudo-first-order kinetics. No additional injections of borohydride or any other H2 source were needed. Ethane was the main reaction product indicating hydrogenolysis as the major dechlorination pathway. Different synthesis parameters were found to affect the oxidation state, elemental composition and the catalytic activity of nPd and consequently 1,2-DCA dechlorination. Detailed surface characterization including TEM, SEM/EDX, XPS and XRD of nPd particles was conducted. This study is an initial step to show that even recalcitrant COCs like 1,2-DCA can be successfully treated in the aqueous-phase via nPdborohydride
suspensions, and likely other nanocatalysts, without any external/additional H2 source. However, further research is needed to provide more insight on how to transfer this technology from ideal laboratory conditions to real-field situations. The results also help provide clues on the development of a process level understanding of 1,2 DCA dechlorination via nanocatalysts.
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Papers by Omneya El-Sharnouby
mesophiles and thermophiles isolates and co-cultures of isolates have been investigated. The co-cultures of the isolates achieved better results than mono-cultures of the isolates with respect to different parameters. This paper presents a critical review of the literature reporting on fermentative biohydrogen production by pure cultures of bacteria in different systems. Synergies between different types of bacteria, i.e. strict and facultative, and a comparison between mono- and co-cultures, types of feedstocks, and preferred feedstocks for mono- and cultures are outlined.
suspensions, and likely other nanocatalysts, without any external/additional H2 source. However, further research is needed to provide more insight on how to transfer this technology from ideal laboratory conditions to real-field situations. The results also help provide clues on the development of a process level understanding of 1,2 DCA dechlorination via nanocatalysts.
mesophiles and thermophiles isolates and co-cultures of isolates have been investigated. The co-cultures of the isolates achieved better results than mono-cultures of the isolates with respect to different parameters. This paper presents a critical review of the literature reporting on fermentative biohydrogen production by pure cultures of bacteria in different systems. Synergies between different types of bacteria, i.e. strict and facultative, and a comparison between mono- and co-cultures, types of feedstocks, and preferred feedstocks for mono- and cultures are outlined.
suspensions, and likely other nanocatalysts, without any external/additional H2 source. However, further research is needed to provide more insight on how to transfer this technology from ideal laboratory conditions to real-field situations. The results also help provide clues on the development of a process level understanding of 1,2 DCA dechlorination via nanocatalysts.