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A surfactant-free, low temperature hydrothermal synthesis of Cu2O nanostructures is demonstrated for application to the photocatalytic degradation of trimethoprim (TMP), an environmental xenobiotic. Photophysical properties of different size and shape Cu2O nanostructures were determined by bulk and surface microscopic and spectroscopic analyses. Visible light photoactivity for the oxidative degradation of TMP is sensitive to the rate of photoexcited charge carrier bulk recombination, and therefore the size of Cu2O crystallites. Optimum photodegradation activity was observed for a hierarchical Cu2O nanostructure, comprising 11 nm crystallites nucleated as 50−80 nm particles, themselves coalesced into 400 nm compact agglomerates. The specific activity of 1.12 μmol.g−1. min−1 for a 0.1 mM TMP aqueous solution is comparable to previous reports that required higher energy and/intensity UV irradiation. The stepwise hydroxylation and oxidative cleavage of TMP to form monocylic fragments is driven by hydroxyl radicals photogenerated over the hierarchical Cu2O nanostructure, which exhibits excellent catalytic stability for >25 h.

Zn-Ti layered double hydroxide/montmorillonite (ZTL/MT) and Fe-doped ZTL/MT (ZTL/Fe@MT20%) were prepared as photocatalyst for Cr(VI) reduction. The ZTL/Fe@MT20% exhibited the highest photocatalytic activity, suggesting that a combination of ZTL and Fe-bearing MT could enhance photocatalytic activity by suppressing the recombination of photogenerated electron-hole pairs. On the basis of electronic-structure calculations, a photocatalytic mechanism for Cr(VI) reduction and the effect of Fe3+ on the structure of MT in ZTL/MT composites is proposed by density functional theory approach, whereby Fe impurities in MT generate a new mid-gap state that induce a Z-scheme heterojunction with ZTL, leading to reduced recombination of the photogenerated charge carriers in ZTL. These results establish that MT can not only act as a support material but also play an important role for photocatalytic reaction when Fe impurities are present in its structure.

Electroplating sludge is classified as a hazardous waste due to its extremely high leachability of potentially toxic elements. This study concerns the use of magnesium oxysulfate cement (MOSC) for the stabilisation/solidification (S/S) of Zn-rich electroplating sludge. According to X-ray diffraction and thermogravimetric analyses, Zn was mainly immobilised through both chemical interaction and physical encapsulation in the MOSC hydrates of 5Mg(OH)2·MgSO4.7H2O (5−1−7) phase. The crystal size analysis, elemental mapping, and extended X-ray absorption fine structure (EXAFS) analysis proved that the Zn2+ was also incorporated in the structure of 5–1–7 phase. Unlike Portland cement system, hydration kinetics, setting time, and compressive strength of the MOSC system were only negligibly modified by the presence of Zn, indicating its superior compatibility. Subsequent S/S experiments demonstrated that the MOSC binder exhibited an excellent performance on immobilisation efficiency of Zn (up to 99.9%), as well as satisfying the requirements of setting time and mechanical strength of sludge S/S products. Therefore, MOSC could be an effective and sustainable binder for the treatment of the Zn-rich industrial wastes.

Sequential treatment was applied to carbonaceous Au-Ag-bearing ore concentrate to maximize the Au and Ag recovery. In the preliminary test, the present carbonaceous ore had well liberated and exposed type of gold grains, which are not refractory, but included mainly three types of Ag presented as electrum, hessite (Ag2Te) and Ag-bearing other minerals. Au recovery was ∼100% without any treatment, meanwhile Ag recovery was only 33.3%. The sequential treatment comprises two oxidation steps: (a) mixed culture of iron- and sulfur-oxidizing microorganisms at pH 1.2, followed by (b) cell-free spent medium (CFSM) at pH 4.0 from a white rot-fungus, Phanerochaete chrysosporium, which includes lignin-degrading enzymes. As a result, Ag recovery was 55.5% after the first step and greatly improved to ∼100%, including the dissolved Ag+ concentration in the first step of acid treatment. Although the acidophilic iron-oxidizing microorganisms were inhibited by dissolved Ag+ and Cd2+ ions, the strong acidic conditions dissolved hessite and Ag-bearing oxide minerals. However, the remaining carbonaceous matter acted to sorb Ag(CN)2− in cyanidation, causing the recovery loss. In the next step the lignin-degrading enzymes degraded carbonaceous matter in the ore. This step is necessary to avoid the adsorption of Ag(CN)2− on graphitic carbonaceous matter, leading a mostly perfect recovery of the remaining Ag in the solid residues, without necessity of alkaline washing. The sequential treatment including enzymatic lignin-degrading process was also effective in carbonaceous silver ore avoiding the emission of air pollutants.

The elevated level of selenium (Se) in the aqueous system presents long-term ecological risks. Hydroxylated calcined dolomites (HCDs) are considered as potentially sustainable lime sources due to their lower production temperatures and resourceful than lime. In this study, HCDs were developed for the removal of Se contaminated water. The HCDs exhibited a better performance to co-precipitate with Se oxyanions than pure Ca(OH)2. Considering that HCDs consisted of Ca(OH)2 with MgO and Mg(OH)2, the function of Mg compounds was also elaborated by various characterization techniques. Mg compounds were proved to enhance the precipitation process and Se removal. STEM-EDX observation revealed that SeO32– was incorporated into the ettringite structure with Mg compounds, whereas SeO42– exhibited a affinity to Mg compounds. Extended X-ray absorption fine structure (EXAFS) results for the MgO/Mg(OH)2 after the reaction proved that both SeO32– interacted with Mg(OH)2 and MgO via inner-sphere complexes whereas SeO42– formed outer-sphere complexes with these Mg compounds. Besides, Mg compounds also influenced the surface charge of solid residues and thus enhanced SeO32– removal. This study provides a fundamental understanding of the roles of Mg compounds in the removal of Se oxyanions during environmental remediation. Besides, the HCDs were proved to be sustainable Ca sources for waste/wastewater remediation.

The pretreatment of carbonaceous material in double refractory gold ores (DRGO) is necessary to decrease preg-robbing of gold and maximize gold recovery. DRGO contains of carbonaceous matter and gold grains encapsulated in sulfide minerals, which typically results in very poor gold recovery. However, there is growing interest in DRGO because some estimates show that it makes up about a third of the total available gold for production by mining. This can be achieved by chemical and biological techniques, however, the chemical techniques like flotation, surface passivation and chemical oxidation have received more extensive study and either have to be retooled or modified to be applied to the carbonaceous matter in the DRGO. In comparison, the biological techniques are relatively unknown with significant gaps in the knowledge about the bio-treatment mechanism, byproducts and avenues for scaling up like bioreactor design. This study reviews the enzymatic pretreatment of DRGO to facilitate gold recovery and minimize reagent consumption. It focuses on the potential for application of oxidative enzymes like lignin peroxidase, manganese peroxidase and laccase to pretreat carbonaceous matter in DRGO with or without an additional step of sulfide oxidation and addresses characterization of byproducts of the enzymatic decomposition. Further, potential bioreactor configurations for the enzymatic decomposition without direct contact of ore with microorganisms are considered, both in terms of understanding the mechanisms within the pretreatment and in terms of application.

In this study, we aimed to decorate nano-ZrO_2 on LaO_x to enhance the architectural stability of LaO_x for the uptake of both arsenate and arsenite in single solutions. LaO_x was obtained as lanthanum methanoate (LaMe) from a simple solvothermal reaction of lanthanum and benzoic acid. The leaving group of formic acid was used as a reducing agent to grow ZrO_2 over LaO_x, which resulted in a nanocomposite denoted as ZrO_2@x%LaMe. The de-arsenic behavior of this composite was compared with that of one-pot-synthesized La-ZrO_2 and ZrO_2@x%La(OH)_3, with La(OH)_3 being obtained commercially. Powder X-ray diffraction patterns showed that the ZrO_2 structure was transformed from monoclinic to tetragonal during the formation of ZrO_2@x%LaMe, La-ZrO_2, and ZrO_2@x%La(OH)_3. Among the synthesized nano-bimetallic composites, ZrO_2@50%LaMe exhibited the highest adsorption densities for both arsenate and arsenite due to the uniform distribution of ZrO_2 over the LaO_x surface resulted in a larger Brunauer–Emmett–Teller specific surface area and a higher zeta potential charge. The synthesized nanocomposites were reused several times with the aid of 0.1 M HNO_3 for maximizing the uptake of both arsenate and arsenite from water. Selectivity and the stability (pH) studies indicated that the nanocomposites were highly selective and showed zero-dissolution behavior, respectively. The results of this study suggested that these nanocomposites could be used as alternatives for many La-based adsorbent materials in practical applications.

Recent decades, the scientific research focused development of sustainable alternative electrocatalytic technologies for efficient energy conversion is intense research field. Rational design of nanodimensional materials meets more attentions due to their promising and high energy conversion efficiency, unique electronic, chemical and physical properties. Herein, we provide an overview of nanodimensional materials design for future sustainable clean energy conversion and systematic framework for designing strategy for future sustainable fine chemicals and fuels. In this chapter, we systematically discuss the range of electrocatalysts, including zero-dimensional to three-dimensional electrocatalysts toward oxygen evolution reaction, hydrogen evolution reaction, oxygen reduction reaction, and various energy technologies such as lasers, light emitting diodes, and solar cells, and their advantages and practical challenges for long-term electrocatalytic application. The overall goal is to achieve a better understanding of developing nanodimensional materials for future sustainable energy.

A novel extract powder purified from the boiled water of adzuki bean paste production was developed to better utilize this resource. The compounds contributing to pigmentation of purified adzuki bean extract powders were investigated in order to compare their antioxidant activity in vitro with (+)-catechin. When a normal extract was exposed to the air under heat treatment, the colour of adzuki bean extract became more strongly reddish, which was associated with polyphenol polymerization. Anthocyanins also contributed to the pigmentation of the purified adzuki bean extracts. Especially, two anthocyanin compounds, peonidin-3-rutinoside and malvidin-3-O-glucoside were newly identified in the adzuki bean extract. The reducing powder, iron chelating activity and free-radical scavenging capacity of the adzuki bean extract were greater than that of (+)-catechin while its total antioxidant value was lower. Thus, adzuki bean extract powders are promising alternatives to replace synthetic antioxidants and potential dyes.

The thermoacidophilic iron-oxidizing archaeon Acidianus brierleyi is a microorganism that could be useful in the removal of inorganic As from wastewater, because it simultaneously oxidizes As(III) and Fe(II) to As(V) and Fe(III) in an acidic culture medium, resulting in the immobilization of As(V) as FeAsO4. To investigate the oxidation mechanism, speciation of the As species in both the cells and its culture media is an important issue. Here we describe the successive determination of As(III), As(V), and total As in A. brierleyi and its culture medium via a facile method based on inductively coupled plasma–optical emission spectroscopy (ICP–OES) with a flow injection pretreatment system using a mini-column packed with an anion-exchange resin. The flow-injection pretreatment system consisted of a syringe pump, a selection valve, and a switching valve, which were controlled by a personal computer. Sample solutions with the pH adjusted to 5 were flowed into the mini-column to retain the anionic As(V), whereas As(III) was introduced into ICP–OES with no adsorption on the mini-column due to its electrically neutral form. An acidic solution (1 M HNO3) was then flowed into the mini-column to elute As(V) followed by ICP–OES measurement. The same sample was also subjected to ICP–OES without being passed through the mini-column in order to determine the total amounts of As(III) and As(V). The method was verified by comparing the results of the total As with the sum of As(III) and As(V). The calibration curves showed good linearity with limits of detection of 158, 86, and 211 ppb for As(III), As(V), and total As, respectively. The method was successfully applicable to the determination of the As species contained in the pellets of A. brierleyi and their culture media. The results suggested that the oxidation of As(III) was influenced by the presence of Fe(II) in the culture medium, i.e., Fe(II) enhanced the oxidation of As(III) in A. brierleyi. In addition, we found that no soluble As species was contained in the cell pellets and more than 60% of the As(III) in the culture medium was oxidized by A. brierleyi after a 6-day incubation.

application/pdf, In this study we compared the hypocholesterolaemic ability of two potato peptide preparations in rats. Experimental groups were fed for 4 weeks, with casein as the basal diet, in comparison with two diets containing 20% potato peptide preparations PPS (Short hydrolysis preparation) and PPL (Long hydrolysis preparation). Serum total cholesterol and serum triglyceride level were lower in PPS-fed group compared with CN-and PPL-fed groups. Lower non-HDL cholesterol level (P