RSC Advances

Gupta, Himanshu

doi: 10.1039/c6ra24602hpmid: N/A

The nano-rods of an iron oxide, akaganeite, were prepared and characterised using X-ray diffraction and field emission scanning electron microscopy. The application of the synthesized nano-rods in the degradation of the polycyclic aromatic hydrocarbon, (phenanthrene) on soil surfaces, was examined. The results reveal the efficient degradation of the pollutant phenanthrene on soil surfaces in the presence of akaganeite nano-rods. The effects of various experimental parameters on the rate of degradation of phenanthrene in the presence of iron oxide were examined. The results indicate that the photodegradation of phenanthrene was fastest under acidic conditions. The rate of photodegradation of phenanthrene increases with the increase in dose of the photocatalyst, akaganeite. The rate of photocatalytic degradation of phenanthrene enhances with the addition of oxalic acid up to the optimum condition due to the occurrence of a Fenton-like mechanism. The intermediate products of phenanthrene formed under acidic, neutral and basic conditions were examined and identified using LC-MS. The results indicated the disappearance of the pollutant phenanthrene after 96 h.

Devi, Manisha; Dhir, Abhimanew; Pradeep, Chullikkattil P.

doi: 10.1039/c6ra22764cpmid: N/A

A series of highly selective and sensitive fluorescent turn-on probes, RHQs 1–4, for the toxic heavy metal ion Pb2+ have been developed based on rhodamine–quinoline conjugates. In these probes, the length of the spacer chain between the rhodamine and quinoline subunits plays important roles in deciding their sensitivity as well as the detection mechanism. By modulating the number of carbons in the spacer from n = 0 to n = 4, the sensitivity of the probes could be altered between 3 μM and 17.4 nM. Moreover, by changing the number of carbons in the spacer from 0 to higher numbers, the detection mechanism of these probes could also be changed from normal fluorescent chemosensing to chemodosimetry. Plausible mechanisms for the chemosensing and chemodosimetry exhibited by these probes have been proposed, which are supported by NMR and HR-MS studies as well. RHQ-1 exhibited reversible complexation and decomplexation behaviours on alternate additions of Pb2+ and CH3COO− ions, respectively, accompanied by fluorescence ON–OFF switching. This property revealed its potential towards the construction of an INHIBIT-type molecular logic gate. RHQs 1–4 exhibited potential for detecting Pb2+ in tap water samples as well as in biological systems.

Xu, Baoqiang; Sohn, Hong Yong; Mohassab, Yousef; Lan, Yuanpei

doi: 10.1039/c6ra90124gpmid: N/A

Correction for ‘Structures, preparation and applications of titanium suboxides’ by Baoqiang Xu et al., RSC Adv., 2016, 6, 79706–79722.

Zhao, Jinlong; Yang, Chunguang; Zhang, Dawei; Zhao, Ying; Khan, M. Saleem; Xu, Dake; Xi, Tong; Li, Xiaogang; Yang, Ke

doi: 10.1039/c6ra22931jpmid: N/A

In this study, the effect of solution temperature on the mechanical properties of the 2205-Cu duplex stainless steel (DSS) was investigated by metallographic observations and tensile tests at room temperature. The corrosion resistance and antibacterial performance of the 2205-Cu DSS were studied by electrochemical potentiodynamic polarization and electrochemical impedance spectroscopy in artificial sea water and co-cultured with Marinobacter salsuginis. X-ray photoelectron spectroscopy was used to analyze the compounds formed on the surface of the specimens. The results showed that the tensile strength and yield strength of 2205-Cu DSS increased slightly with an increase in solution temperature. Correspondingly, due to the minor enhancement of ferrite content, both the pitting corrosion potential and antibacterial property were improved. This was mainly attributed to the surface enrichment of Cr2O3, Cr(OH)3 and Cu and to the decreased uniform corrosion resistance, which stimulated the release of more Cu2+ ions and resulted in improved antibacterial properties.

Fashi, Armin; Khanban, Fatemeh; Yaftian, Mohammad Reza; Zamani, Abbasali

doi: 10.1039/c6ra20479apmid: N/A

A novel method of electromembrane extraction combined with HPLC analysis was applied for preconcentration–determination of chloramphenicol (CAP) residues in dairy products. It is shown that the presence of the cationic surfactant cetyltrimethylammonium bromide (CTAB) in the sample solution, and reduced graphene oxide (RGO) in the solvent membrane, results in the enhancement of the anionic analyte extraction into the acceptor phase. In fact, the addition of CTAB leads the accumulation of the analyte at the sample solution/supported liquid membrane (SLM) interface, and thus amelioration of the analyte transfer rate to the acceptor phase. The effect of RGO on this process comes from its efficient sorbent characteristic which augments the overall analyte partition coefficient into the SLM. The main parameters that affect the extraction efficiency were examined and optimized. Under the optimized conditions, the proposed method provided acceptable linearity (0.04–250 ng g−1), satisfactory repeatability and reproducibility (CV% < 5.5), low LODs (0.012–0.021 ng g−1) with high preconcentration factors (195–255) in the different samples. Finally, the proposed method was successfully applied to the evaluation of CAP residues in dairy products.

Ma, Chunxia; Pei, Haiyan; Hu, Wenrong; Xu, Hangzhou; Jin, Yan

doi: 10.1039/c6ra24635dpmid: N/A

Coagulation is a key unit operation for cyanobacterial cell removal; however, the potential danger of cyanobacterial cells transferred into sludge is not well understood. In this study, the fate of Microcystis aeruginosa (M. aeruginosa) and secondary metabolites in chitosan–aluminium chloride (CTSAC) coagulated cyanobacteria-laden sludge were investigated during the sludge storage period. The extracellular microcystins (MCs) can be adsorbed onto the CTSAC flocs for six days with a reduced biodegradation rate. Less M. aeruginosa cell lysis was observed in the coagulated system than in the natural cell system, due to the protection of M. aeruginosa by the CTSAC. Furthermore, the residual Al content decreased in the cyanobacteria-laden sludge supernatant. The amount of extracellular organic matter (EOM) stayed low in the coagulated system for four days. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis showed that coexisting bacteria reduced in the sludge during the initial four days storage time. Interestingly, the CTSAC degradation favored the growth of the M. aeruginosa cells. This study will be helpful for better understanding and managing secondary metabolite pollution problems related to coagulation-generated cyanobacteria-laden sludge during the sludge supernatant recycling process. The use of CTSAC composite coagulant is of practical value in reducing secondary pollution during cyanobacteria-laden sludge storage.

Jiang, Tengfei; Bujoli-Doeuff, Martine; Farré, Yoann; Pellegrin, Yann; Gautron, Eric; Boujtita, Mohammed; Cario, Laurent; Jobic, Stéphane; Odobel, Fabrice

doi: 10.1039/c6ra17879kpmid: N/A

In p-type dye-sensitized solar cells (p-DSSCs), NiO is the most commonly used p-type semiconductor. Nevertheless, because of the drawbacks of NiO, much effort has been made to search for suitable substitutes. Herein, three different morphologies of CuO nanomaterials were used to prepare photocathodes for p-DSSCs, which have a deeper valence band and a higher dielectric constant compared to that of NiO. We observe that CuO is unstable in the presence of iodide/triiodide electrolyte, while cobalt complexes with bipyridine ligands are more suitable redox shuttles. We also note that the average transport time in CuO is shorter than that in NiO. Finally, the deep absorbance of CuO in the visible range indicates that suitable sensitizers for the CuO p-DSSC must exhibit high extinction coefficient and absorption bands located in the lower energy part of the solar spectrum (>600 nm) to be exploitable. In this case such CuO based photocathodes represent valuable systems to exploit the near-infrared (NIR) region.

Beiranvand, Z.; Kakanejadifard, A.; Donskyi, I. S.; Faghani, A.; Tu, Z.; Lippitz, A.; Sasanpour, P.; Maschietto, F.; Paulus, B.; Unger, W. E. S.; Haag, R.; Adeli, M.

doi: 10.1039/c6ra23419dpmid: N/A

In this work, fullerene has been functionalized with cyanuric chloride at room temperature by a nitrene mediated [2 + 1] cycloaddition reaction. The adduct after functionalization is inherently in the form of azafulleroid and shows broad UV absorption in the wavelength range of 200–800 nm, as well as photothermal conversion and fluorescence with a high quantum yield.

Ratanasak, Manussada; Parasuk, Vudhichai

doi: 10.1039/c6ra22101gpmid: N/A

Roles of a novel dibenzoyl sulfide donor in Ziegler–Natta (ZN) catalyzed propylene polymerization were examined using DFT calculations. The adsorption mode for dibenzoyl sulfide and diisobutyl phthalate electron donors on the MgCl2(110) surface is the chelate coordination mode, similar to malonate electron donors. The dibenzoyl sulfide/diisobutyl phthalate donor provides regio- and stereo-selectivity to the ZN catalyst. Factors that control the isotacticity and activity of the ZN catalyst are steric repulsion and π-complex stabilization by electron donors. The steric repulsion signifies intrinsic activation energy and π-complex formation energy for π-complex stabilization. The two factors are combined in the apparent activation energy and dibenzoyl sulfide gives the lowest apparent activation energy. Therefore, dibenzoyl sulfide shows the best catalytic enhancement as compared to diisobutyl phthalate and di-n-butyl-2-cyclopentyl malonate, which is in good agreement with the results obtained from the experiments.

Assunção, Ana; Vieira, Bernardete; Lourenço, João P.; Costa, Maria Clara

doi: 10.1039/c6ra24503jpmid: N/A

The use of biological processes with the aim of the recovery of gold from low-concentration solutions derived from leaching of secondary sources is gaining increasing importance owing to the scarcity of the primary resources and the economic and environmental advantages usually presented by these methods. Thus, the addition in batch and continuous processes of different solutions containing biogenic sulphide, which was generated by the activity of sulphate-reducing bacteria (SRB), to gold(iii) solutions was investigated for that purpose. In the batch experiments, AuS nanoparticles with sizes of between 6 and 14 nm were obtained (corresponding to 100% removal of Au(iii) from solution) if the biogenic sulphide was generated in a typical nutrient medium for SRB, whereas Au(0) nanoparticles with sizes of below 8 nm were obtained (corresponding to 62% removal of Au(iii)) if effluent from a SRB bioremediation process for treating acid mine drainage (AMD) was used instead. These results stimulated the development of a continuous process of addition, in which two sulphide-rich effluents, which resulted from a SRB bioremediation process for treating two types of AMD (from a uranium mine and a polysulphide mine), were tested. In both cases, Au(0) nanoparticles with sizes of between 6 and 15 nm were mainly obtained, and the percentage removal of Au(iii) from solution ranged from 76% to 100%. The processes described allow the simultaneous treatment of AMD and recovery of metallic gold nanoparticles, which are a product with a wide range of applications (e.g., in medicine, optical devices and catalysis) and high economic value. The synthesis process described in this work can be considered as novel, because it is the first time, to our knowledge, that the use of effluent from a SRB bioremediation process has been reported for the recovery of gold(iii) as gold(0) nanoparticles.