Advanced Oxidation/Reduction Processes treatment for aqueous perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) – A review of recent advances

Removal of organic compounds by nanoscale zero-valent iron and its composites.

Designer carbon nanotubes for contaminant removal in water and wastewater: A critical review

Ozone is a strong oxidant and have been effectively used for the degradation and mineralization of organic pollutants. However, the increase in the toxicity and disposal of the recalcitrant organics standalone ozonation process is not effective and sustainable solution for the treatment of industrial wastewater containing recalcitrant. It is therefore necessary to provide a summary of success of hybrid ozonation process for industrial wastewater treatment along with the reaction mechanism for enhancing the molecular ozone reactivity. The paper presents a detailed review of hybrid ozonation process as a combination of two different techniques to enhance the hydroxyl radical formation thereby increasing the process efficiency. An extensive review on the mechanism and application of these hybrid ozonation processes for degradation, mineralization, detoxification of different organic pollutants present in the industrial wastewater is reported.

Hybrid ozonation process for industrial wastewater treatment: Principles and applications: A review

Present and past anthropogenic pollution of the hydrosphere and lithosphere is a growing concern around the world for sustainable development and human health. Current industrial activity, abandoned contaminated plants and mining sites, and even everyday life is a pollution source for our environment. There is therefore a crucial need to clean industrial and municipal effluents and remediate contaminated soil and groundwater. Nanosized zero-valent iron (nZVI) is an emerging material in these fields due to its high reactivity and expected low impact on the environment due to iron's high abundance in the earth crust. Currently, there is an intensive research to test the effectiveness of nZVI in contaminant removal processes from water and soil and to modify properties of this material in order to fulfill specific application requirements. The number of laboratory tests, field applications, and investigations for the environmental impact are strongly increasing. The aim of the present review is to provide an overview of the current knowledge about the catalytic activity, reactivity and efficiency of nZVI in removing toxic organic and inorganic materials from water, wastewater, and soil and groundwater, as well as its toxic effect for microorganisms and plants.

Synthesis and Application of Zero-Valent Iron Nanoparticles in Water Treatment, Environmental Remediation, Catalysis, and Their Biological Effects

Simultaneous formation of nanoscale zero-valent iron and degradation of nitrobenzene in wastewater in an impinging stream-rotating packed bed reactor

Effects on the removal efficiency of nitrobenzene treated by O3/H2O2 in a rotating packed bed (RPB) were optimized with response surface methodology (RSM). Interaction effects between influence of H2O2 concentration, gas-phase ozone concentration, liquid flow rate, and high-gravity factor on the removal efficiency of nitrobenzene wastewater treatment with O3/H2O2 in a RPB were investigated. The results indicate that the influence priority on nitrobenzene removal is high-gravity factor, gas-phase ozone concentration, H2O2 concentration, and liquid flow rate. Significant interaction effects of H2O2 concentration and gas-phase ozone concentration, gas-phase ozone concentration, and high-gravity factor were observed. The optimum treatment conditions after optimizing were H2O2 concentration 5.7 mmol L−1, gas-phase ozone concentration 50 mg L−1, liquid flow rate 125 L h−1, and high-gravity factor 100. Under the optimal reaction conditions, the actual removal efficiency of nitrobenzene could reach 76.1% ...

Optimization of nitrobenzene wastewater treatment with O3/H2O2 in a rotating packed bed using response surface methodology

Nanoscaled zerovalent iron (NZVI)–multiwalled carbon nanotubes (CNTs) composite materials were prepared by in situ reduction of Fe2+ onto CNTs for nitrobenzene (NB) degradation. The morphologies and the composites of the prepared materials were characterized by SEM, TEM, and XRD. The results showed that the agglomeration of NZVI decreased with NZVI dispersed well onto the surfaces of CNTs, the particle size of NZVI on CNTs was about 20–50 nm. The BET surface areas of NZVI–CNTs was about 95.8 m2/g, which was 39 % higher than that of bare NZVI. For storage, the prepared NZVI–CNTs were concentrated into slurry and stored in situ as fresh slurry without drying. Contrast experiment results showed that the removal efficiency of NB by NZVI–CNTs fresh slurry was 30 % higher than that of vacuum-dried NZVI–CNTs, which indicates that storing in situ as fresh slurry can be an alternative strategy for nanoparticle storage. Batch experiment results showed that NB could be degraded to aniline by NZVI–CNTs rapidly, and the appropriate pH can be conducted at a relatively wide range from 2.0 to 9.0. The optimum mass ratio of iron–carbon was 1:1, and removal efficiency of NB by NZVI–CNTs with this mass ratio can achieve 100 % within 1 min. The degradation process of NB to intermediates was accelerated significantly by NZVI–CNTs, however, there was still a long term for the intermediates to transfer completely into the final product of aniline. The existence of CNTs can improve the formation of aniline through accelerating the electron transfer by forming microscopic galvanic cells with NZVI.

Degradation of nitrobenzene-containing wastewater by carbon nanotubes immobilized nanoscale zerovalent iron

Nanoscale zero-valent iron (nZVI) was continuously prepared by high-gravity reaction precipitation through a novel impinging stream-rotating packed bed (IS-RPB). Reactant solutions of FeSO4 and NaBH4 were conducted into the IS-RPB with flow rates of 60 L/h and rotating speed of 1000 r/min for the preparation of nZVI. As-prepared nZVI obtained by IS-RPB were quasi-spherical morphology and almost uniformly distributed with a particle size of 10–20 nm. The reactivity of nZVI was estimated by the degradation of 100 ml nitrobenzene (NB) with initial concentration of 250 mg/L. The optimum dosage of nZVI obtained by IS-RPB was 4.0 g/L as the NB could be completely removed within 10 min, which reduced 20% compared with nZVI obtained by stirred tank reactor (STR). The reduction of NB and production of aniline (AN) followed pseudo-first-order kinetics, and the pseudo-first-order rate constants were 0.0147 and 0.0034 s−1, respectively. Furthermore, the as-prepared nZVI using IS-RPB reactor in this work can be used within a relatively wide range pH of 1–9.

Continuous preparation of nanoscale zero-valent iron using impinging stream-rotating packed bed reactor and their application in reduction of nitrobenzene

The invention belongs to the technical field of reacting and mass transferring in a high gravity field, and provides a constant-channel type rotating-packed-bed mass transferring and reacting device. The constant-channel type rotating-packed-bed mass transferring and reacting device aims at solving the problems that an existing high gravity reacting and mass transferring device is low in packing use rate, and therefore mass transferring performance is influenced; the amount of use packing is large, the running rotating inertia is large, and amplification and maintaining of the device are not facilitated. The packing is a concentric ring body composed of packing parts A and packing parts B alternately. The packing parts A are gas-liquid flowing passages and are each composed of a plurality of hexahedron cubes, metal wire meshes are wound around the inner surfaces and the outer surfaces of the packing parts A in the radial direction, the other four planes of each packing part A are composed of metal flat plates, and the interiors are filled with bulk packing; the packing parts B are sector-shaped body structural supporting pieces, and the five planes of each packing part B are composed of meal flat plates. Gas-liquid distribution is obviously improved, and the gas-liquid-phase mass transferring coefficients are both increased; the cost for a high gravity device is reduced, rotating inertia is remarkably reduced, the abrasion condition of a transmission shaft is improved, a gas film control process is enhanced, and the constant-channel type rotating-packed-bed mass transferring and reacting device can be used for the absorption process of low-concentration gas.

Feng Zhirong

Papers

Simultaneous formation of nanoscale zero-valent iron and degradation of nitrobenzene in wastewater in an impinging stream-rotating packed bed reactor

Optimization of nitrobenzene wastewater treatment with O3/H2O2 in a rotating packed bed using response surface methodology

Degradation of nitrobenzene-containing wastewater by carbon nanotubes immobilized nanoscale zerovalent iron

Continuous preparation of nanoscale zero-valent iron using impinging stream-rotating packed bed reactor and their application in reduction of nitrobenzene

Constant-channel type rotating-packed-bed mass transferring and reacting device