Carbon-Based Nanomaterials for Catalytic Wastewater Treatment: A Review

Carbon-based nanomaterials (CBM) have shown great potential for various environmental applications because of their physical and chemical properties. The unique hybridization properties of CBMs allow for the tailored manipulation of their structures and morphologies. However, owing to poor solar light absorption, and the rapid recombination of photogenerated electron-hole pairs, pristine carbon materials typically have unsatisfactory photocatalytic performances and practical applications. The main challenge in this field is the design of economical, environmentally friendly, and effective photocatalysts. Combining carbonaceous materials with carbonaceous semiconductors of different structures results in unique properties in carbon-based catalysts, which offers a promising approach to achieving efficient application. Here, we review the contribution of CBMs with different dimensions, to the catalytic removal of organic pollutants from wastewater by catalyzing the Fenton reaction and photocatalytic processes. This review, therefore, aims to provide an appropriate direction for empowering improvements in ongoing research work, which will boost future applications and contribute to overcoming the existing limitations in this field.

Black pearl carbon as a catalyst for all-vanadium redox flow batteries

We report for the first time, the performance of black pearl (BP) carbon as an electrocatalyst in all-vanadium redox-flow-batteries. Our results show significant suppression in peak potential separation (faster in kinetics than CNTs), 17% improvement in energy efficiency (when compared with CNTs) and good activity retention after 800 potential cycles.

A review of solar and visible light active oxo-bridged materials for energy and environment

Oxo-bridged systems are versatile photo-redox catalysts for environmental decontamination and artificial photosynthesis.

Dramatic activities of vanadate intercalated bismuth doped LDH for solar light photocatalysis

To harvest solar energy efficiently, a series of Zn/Bi layered double hydroxide (LDH) photocatalysts with different molar ratios of Zn/Bi (2 : 1, 3 : 1, 4 : 1) has been synthesized by a coprecipitation method at constant pH. All the Bi doped LDH samples displayed hydrotalcite-like structure with interlayer carbonate, in which crystallinity decreases as the bismuth content increases. The Zn/Bi (4 : 1) LDH with a small amount of bismuth in the brucite layer and possessing high crystallinity was further modified hydrothermally by intercalating decavanadate and it showed high photochemical stability and photocatalytic activity for the degradation of different organic pollutants for practical applications under solar light irradiation. The structural integrity of the materials has been successfully characterized by studying their structural, morphological, electronic and optical properties by various physico-chemical techniques. The present study provided an insight into oxo-bridged MMCT of the LDH and established that the Zn(II)-O-Bi(III) units resulted in the generation of superoxide radicals which is clearly observed by the EPR technique. The ˙OH radicals formed during photocatalysis were revealed by means of the terephthalic acid fluorescence probe method. The photoelectrochemical measurement confirmed that the intercalated vanadate anion was crucial to obtain an optimal synergistic effect for the degradation of organic pollutants. The prolonged lifetime of photogenerated charges and improved charge transfer capability were confirmed by time-resolved fluorescence emission spectra. Furthermore, a detailed mechanism for the enhanced photocatalytic activity was discussed.

Nano-structured Mg-doped Fe2O3-ferrihydrite powder--a new adsorbent for cation removal from aqueous solutions

The present studies were undertaken with a view to developing a low-cost, efficient adsorbent for removal of heavy metal ions from aqueous solutions. A new cost-effective nano-structured Mg-doped Fe2O3-ferrihydrite adsorbent exhibiting high uptake capacities for various cations was synthesized. After preliminary testing of a series of Mg-doped (0.38 to 0.98%) samples for Pb(II), Cd(II), Cu(II) or Co(II) adsorption, a typical sample containing 55.7% Fe and 0.38% Mg was chosen for detailed characterization studies (XRD, TG-DTA, FTIR and TEM techniques). The adsorption behaviour of cations on the prepared nano powder was studied under various experimental conditions. The generated data were fitted to kinetic and isotherm models. The Langmuir monolayer capacities were 99.1, 83.3, 111.1 and 151.5 mg/g for Pb(II), Cd(II), Cu(II) and Co(II), respectively. It is the first time that such a high loading capacity for Co(II) has been reported. The effect of the presence of chloride or sulphate was dependent on the nature of the cation. Lead(II) adsorption was endothermic in nature with increased randomness at the solid-liquid interface, while for the rest of the three cations the adsorption process was exothermic. The XRD and FTIR studies on the loaded samples revealed structural changes during the adsorption process. The high cation loading capacities along with the stability of the loaded adsorbent make the synthesized ferrihydrite-Fe2O3 nano powder a potential candidate for contaminated water purification.

Temporal stability of saccadic task performance in schizophrenia and bipolar patients

BACKGROUND

Identifying endophenotypes of schizophrenia will assist in the identification of individuals who are at heightened risk for the disorder. Investigators have proposed antisaccade task deficits as an endophenotypic marker of schizophrenia. However, the diagnostic specificity and the temporal stability of the task deficit are unresolved issues. To date, there are few published reports of test-retest stability of antisaccade task performance in psychiatric patients.

METHOD

Twenty-three schizophrenia out-patients and 10 bipolar out-patients were administered two saccadic (antisaccade and refixation) tasks at two separate assessments, with an average test retest interval of 33 months.

RESULTS

The schizophrenia patients displayed high test-retest reliabilities of antisaccade task accuracy, despite changes in medication and clinical status. Additionally, the schizophrenia group's saccadic reaction times for antisaccade correct responses and task errors were moderately stable over time. In contrast, the bipolar patients did not show temporal stability in their antisaccade task accuracy or in their response latencies to either correct or incorrect antisaccade responses.

CONCLUSIONS

The results are supportive of the trait-like characteristics of antisaccade task deficits in schizophrenia patients. These findings also suggest that antisaccade task deficits may serve as an endophenotypic marker of schizophrenia.