Hongtao Lu

Fenton-Like Catalysis and Oxidation/Adsorption Performances of Acetaminophen and Arsenic Pollutants in Water on a Multimetal Cu–Zn–Fe-LDH

Acetaminophen can increase the risk of arsenic-mediated hepatic oxidative damage; therefore, the decontamination of water polluted with coexisting acetaminophen and arsenic gives rise to new challenges for the purification of drinking water. In this work, a three-metal layered double hydroxide, namely, Cu-Zn-Fe-LDH, was synthesized and applied as a heterogeneous Fenton-like oxidation catalyst and adsorbent to simultaneously remove acetaminophen (Paracetamol, PR) and arsenic. The results showed that the degradation of acetaminophen was accelerated with decreasing pH or increasing H2O2 concentrations. Under the conditions of a catalyst dosage of 0.5 g·L(-1) and a H2O2 concentration of 30 mmol·L(-1), the acetaminophen in a water sample was completely degraded within 24 h by a Fenton-like reaction. The synthesized Cu-Zn-Fe-LDH also exhibited a high efficiency for arsenate removal from aqueous solutions, with a calculated maximum adsorption capacity of 126.13 mg·g(-1). In the presence of hydrogen peroxide, the more toxic arsenite can be gradually oxidized into arsenate and adsorbed at the same time by Cu-Zn-Fe-LDH. For simulated water samples with coexisting arsenic and acetaminophen pollutants, after treatment with Cu-Zn-Fe-LDH and H2O2, the residual arsenic concentration in water was less than 10 μg·L(-1), and acetaminophen was not detected in the solution. These results indicate that the obtained Cu-Zn-Fe-LDH is an efficient material for the decontamination of combined acetaminophen and arsenic pollution.

Enhanced photocatalytic activity of Ce-doped Zn-Al multi-metal oxide composites derived from layered double hydroxide precursors.

In this work, a series of novel Zn-Al-Ce multi-metal oxide (Zn-Al-Ce-MMO) photocatalysts with different Ce doping contents were prepared by calcination of Ce-doped Zn-Al layered double hydroxide (Zn-Al-Ce-LDH) precursors at various temperatures in air atmosphere. The synthesized Zn-Al-Ce-MMO materials were characterized by XRD, FTIR, TGA, BET, SEM, TEM, XPS and UV-vis DRS. The photocatalytic activities of the Zn-Al-Ce-MMO materials were evaluated by the photodegradation of rhodamine B (RhB) dye and paracetamol in aqueous solution under simulated solar light irradiation. The result of photodegradation of RhB showed that the Zn-Al-Ce-MMO samples exhibit much higher photocatalytic activity than that of Zn-Al-MMO, and the optimal Ce doping content is 5% of mole ratio (nCe/n(Zn+Al+Ce)). The enhanced photocatalytic activity of the Zn-Al-Ce-MMO was mainly attributed to the increasing in the separation efficiency of electrons and holes. The effect of calcination temperature was also studied. The photocatalytic activity of Zn-Al-Ce-MMO increased with increasing calcination temperature up to 750°C, which can be ascribed to the formation of well-crystallized metal oxides during calcination. Under experimental conditions, 97.8% degradation efficiency of RhB and 98.9% degradation efficiency of paracetamol were achieved after 240min. Active species trapping and EPR experiments suggested that hole (h(+)), superoxide radical (O2(-)) and hydroxyl radical (OH) played important roles during the RhB photocatalytic process. Moreover, the results indicated that the synthesized Zn-Al-Ce-MMO materials had good stability and reusability.

Enhanced adsorption performance of aspartic acid intercalated Mg-Zn-Fe-LDH materials for arsenite

A series of hydrophobic and hydrophilic amino acid (aspartic acid, phenylalanine, glutamic acid, and proline) intercalated LDH materials were synthesized and characterized. The results of batch experiments showed that Mg7Zn1Fe4-Asp-LDH and Mg7Zn1Fe4-Phe-LDH showed good adsorption performances for both arsenate and arsenite in aqueous solutions. The effects of various experimental conditions have been investigated by the batch test, which included the effects of initial pH, arsenic concentration, contact time and coexisting ions. For Mg7Zn1Fe4-Asp-LDH under the optimal experimental conditions, the maximum adsorption capacity of As(iii) and As(v) reached 94.81 mg g-1 and 57.42 mg g-1, respectively. It showed a higher adsorption capacity for As(iii) than that for As(v), which is of great significance to remove the trivalent arsenic species with higher toxicity. When the dosage of Mg7Zn1Fe4-Asp-LDH was 0.8 g L-1, the concentration of As(iii) in the aqueous solution could be reduced from 2 mg L-1 to below 10 μg L-1.When Mg-Zn-Fe-Asp-LDH was applied in practical water samples with a dosage of 0.2 g L-1, the residual concentrations of arsenic in three actual water samples were all lower than 10 μg L-1 after adsorption. The column test showed that 1.0 g of Mg7Zn1Fe4-Asp-LDH could continuously treat 2.6 L of As(iii) aqueous solution (2 mg L-1) and reduced the concentration of As(iii) to below 10 μg L-1 or handle 0.4 L of arsenic-contaminated (10 mg L-1, As(iii) : As(v) = 1 : 1) water, and the effluent concentration was below 10 μg L-1. Compared with the previously reported hydrophobic amino acid intercalated LDHs, aspartic acid (hydrophilic amino acid) intercalated LDH has a good removal efficiency for arsenic. The synthesized Mg7Zn1Fe4-Asp-LDH is considered to be a potentially functional material that can be used to treat arsenic contamination in water.

Fenton-like Catalytic Performance of CuFe-LDH for Degradation of Florfenicol

In this paper, the Cu-Fe layered double hydroxide (CuFe-LDH) was synthesized via co-precipitation method and applied as a heterogeneous Fenton-like catalyst to remove a typical veterinary antibiotic florfenicol. The effects of catalyst dosage, H2O2 concentration and initial pH value on the removal of florfenicol in aqueous solutions were investigated. The possible mechanism of the catalytic reaction was discussed. The results indicated that florfenicol can be effectively removed under the experimental conditions with heterogeneous Fenton-like reaction in the presence of CuFe-LDH. The removal efficiency can achieve nearly 100% with 10 mmol/L of H2O2 concentration. The synthesized CuFe-LDH as a catalyst can adapt the pH range of 5-9, and showed a good performance after several repeated use.