Jinhong Fan

Novel iron metal matrix composite reinforced by quartz sand for the effective dechlorination of aqueous 2-chlorophenol

In this work, we tested a novel iron metal matrix composite (MMC) synthesized by mechanically introducing quartz sand (SiO2) into an iron matrix (denoted as SiO2-Fe MMC). The pseudo-first-order reaction rate constant of the SiO2-Fe MMC (initial pH 5.0) for 20 mg/L of 2-chlorophenol (2-CP) was 0.051 × 10(-3) L/m(2)/min, which was even higher than that of some reported Pd/Fe bimetals. This extraordinary high activity was promoted by the quick iron dissolution rate, which was caused by the formation of Fe-C internal electrolysis from carbonization of process control agent (PCA) and the active reinforcement/metal interfaces during the milling process. In addition, pH has slight effect on the dechlorination rate. The SiO2-Fe MMC retained relatively stable activity, still achieving 71% removal efficiency for 2-CP after six consecutive cycles. The decrease in dechlorination efficiency can be attributed to the rapid consumption of Fe(0). A dechlorination mechanism using the SiO2-Fe MMC was proposed by a direct electron transfer from Fe(0) to 2-CP at the quartz sand/iron interface.

Speciation and formation of iodinated trihalomethane from microbially derived organic matter during the biological treatment of micro-polluted source water.

Water sources are micro-polluted by the increasing range of anthropogenic activities around them. Disinfection byproduct (DBP) precursors in water have gradually expanded from humic acid (HA) and fulvic acid to other important sources of potential organic matter. This study aimed to provide further insights into the effects of microbially derived organic matter as precursors on iodinated trihalomethane (I-THM) speciation and formation during the biological treatment of micro-polluted source water. The occurrence of I-THMs in drinking water treated by biological processes was investigated. The results showed for the first time that CHCl2I and CHBrClI are emerging DBPs in China. Biological pre-treatment and biological activated carbon can increase levels of microbes, which could serve as DBP precursors. Chlorination experiments with bovine serum albumin (BSA), starch, HA, deoxyribonucleic acid (DNA), and fish oil, confirmed the close correlation between the I-THM species identified during the treatment processes and those predicted from the model compounds. The effects of iodide and bromide on the I-THM speciation and formation were related to the biochemical composition of microbially derived organic precursors. Lipids produced up to 16.98μgL(-1) of CHCl2I at an initial iodide concentration of 2mgL(-1). HA and starch produced less CHCl2I at 3.88 and 3.54μgL(-1), respectively, followed by BSA (1.50μgL(-1)) and DNA (1.35μgL(-1)). Only fish oil produced I-THMs when iodide and bromide were both present in solution; the four other model compounds formed brominated species.

Industrial wastewater advanced treatment via catalytic ozonation with an Fe-based catalyst

An Fe-based catalyst was used as a heterogeneous catalyst for the ozonation of industrial wastewater, and key operational parameters (pH and catalyst dosage) were studied. The results indicated that the Fe-based catalyst significantly improved the mineralization of organic pollutants in wastewater. TOC (total organic carbon) removal was high, at 78.7%, with a catalyst concentration of 200 g/L, but only 31.6% with ozonation alone. The Fe-based catalyst significantly promoted ozone decomposition by 70% in aqueous solution. Hydroxyl radicals (·OH) were confirmed to be existed directly via EPR (electron paramagnetic resonance) experiments, and ·OH were verified to account for about 34.4% of TOC removal with NaHCO3 as a radical scavenger. Through characterization by SEM-EDS (field emission scanning electron microscope with energy-dispersive spectrometer), XRD (X-ray powder diffraction) and XPS (X-ray photoelectron spectroscopy), it was deduced that FeOOH on the surface of the catalyst was the dominant contributor to the catalytic efficiency. The catalyst was certified as having good stability and excellent reusability based on 50 successive operations and could be used as a filler simultaneously. Thereby, it is a promising catalyst for practical industrial wastewater advanced treatment.

Oxalate-assisted oxidative degradation of 4-chlorophenol in a bimetallic, zero-valent iron-aluminum/air/water system.

The reaction of zero-valent iron and aluminum with oxygen produced reactive oxidants that can oxidize 4-chlorophenol (4-CP). However, oxidant yield without metal surface cleaning to dissolve the native oxide layer or in the absence of ligands was too low for practical applications. The addition of oxalate (ox) to dissolved oxygen-saturated solution of Fe0–Al0 significantly increased oxidant yield because of the dissolution, pH buffer, and complexing characteristics of ox. Ox-enhanced reactive oxidant generation was affected by ox concentration and solution pH. The critical effect of ox dosing was confirmed with the reactive species of [FeII(ox)0] and [FeII(ox)22−]. Systematic studies on the effect of the initial and in situ solution pH revealed that 4-CP oxidation was controlled by the continuous release of dissolved Fe2+ and Al3+, their fate, and the activation mechanisms of O2 reduction. The degradation pathway of 4-CP in ox-enhanced Fe0–Al0/O2 may follow the 4-chlorocatechol pathway. The robustness of the ox-enhanced Al0–Fe0–O2 process was determined with one-time dosing of ox. Therefore, ox is an ideal additive to enhancing the Fe0–Al0/O2 system for the oxidative degradation of aqueous organic pollutants.

Enhancing simultaneous removal of nitrogen and phosphorus from municipal wastewater by Fe–Cu shavings

AbstractTo alleviate the environmental stress and meet the increasingly strict regulation requirements for total nitrogen (TN) and total phosphorus (TP) discharge, hybrid system of Fe–Cu shavings with activated sludge was studied in a lab-scale to treat actual municipal wastewater. The results showed that Fe–Cu shavings could enhance TN and TP removal from municipal wastewater without external carbon source addition. Compared with the simple biological system, TP and TN removal efficiency raised about 30 and 10%, respectively, in the hybrid system at temperature of 3–26.5°C, while the improvement of COD removal was not obvious. Moreover, total ferrum concentration of the effluent was lower than 0.6 mg/L, no additional metal pollution appeared. Therefore, a new N&P removal technology is proposed, which provides an easy implementation and effective upgrading to the existing wastewater treatment plants.