Improvement of Photocatalytic Degradation of Naphthol Green B Under Solar Light Using Aluminum Doping of Zinc Oxide Nanoparticles

The photocatalytic degradation of dyes under sunlight irradiation has received much attention not only because the attempt is aimed at decomposition of pollutants but also at finding methods of making use of solar energy. Following this line, zinc oxide nano-particles were prepared using solvent thermal method in order to decompose Naphthol Green B in presence of sunlight. Complete mineralization and decolorization of Naphthol Green B were achieved in 14?h. In order to reduce the band gap of zinc oxide and increase its photocatalytic activity in sunlight, it was doped with different concentrations of aluminum (1?%, 3?%, 5?%, and 10?%). The obtained band gap energy of the Al-doped ZnO nanoparticles was investigated as a function of Al content. Reduction of band gap energy for the heavily doped ZnO nanoparticles (10?% Al) was observed from 3.29 to 3.23?eV leading to fast transfer for electron from the excited state of dye to conduction band of ZnO. Therefore, by using the 10?% Al-doped ZnO nanoparticles, the complete mineralization and decolorization of Naphthol Green B were achieved in 6?h under sunlight. These results suggested that the heavily doped ZnO nanoparticles with aluminum has a positive effect towards photocatalytic reactions with dye under solar energy.     

Removal of Dyes Using Graphene-Based Composites: a Review

Water contamination has reached an alarming state due to industrialization and urbanization and has become a worldwide issue. Dyes contaminate water and are addressed extensively by researchers. Various technologies and materials have been developed for the treatment of contaminated water. Among them, adsorption has attracted great attention due to its ease and cost-effective nature. In recent years, graphene-based composites have shown great potential for the removal of contaminants from water. The literature reveals the usefulness of composites of graphene with metal oxides, carbon derivatives, metal hybrids and polymers for the removal of organic dyes from contaminated water. In this review, efforts have been made to compile the studies on the removal of cationic and anionic dyes from water using graphene-based composites.     

Highly Efficient Removal of Cu(II) from Aqueous Solution by Using Graphene Oxide

Chemical reagents used by the textile industry are very diverse in their composition, ranging from inorganic compounds to polymeric compounds. Strong color is the most notable characteristic of textile effluents, and a large number of processes have been employed for color removal. In recent years, attention has been directed toward various natural solid materials that are able to remove pollutants from contaminated water at low cost, such as sugarcane bagasse. Cell immobilization has emerged as an alternative that offers many advantages in the biodegradation process, including the reuse of immobilized cells and high mechanical strength, which enables metabolic processes to occur under adverse conditions of pH, sterility, and agitation. Support treatment also increases the number of charges on the surface, thereby facilitating cell immobilization processes through adsorption and ionic bonds. Polyethyleneimine (PEI) is a polycationic compound known to have a positive effect on enzyme activity and stability. The aim of the present study was to investigate a low-cost alternative for the biodegradation and bioremediation of textile dyes, analyzing Saccharomyces cerevisiae immobilization in activated bagasse for the promotion of Acid Black 48 dye biodegradation in an aqueous solution. A 1 % concentration of a S. cerevisiae suspension was evaluated to determine cell immobilization rates. Once immobilization was established, biodegradation assays with free and immobilized yeast in PEI-treated sugarcane bagasse were evaluated for 240 h using UV–vis spectrophotometry. The analysis revealed significant relative absorbance values, indicating the occurrence of biodegradation in both treatments. Therefore, S. cerevisiae immobilized in sugarcane bagasse is very attractive for use in biodegradation processes for the treatment of textile effluents.     

Zinc Biofortification in Sixty Groundnut Cultivars Through Foliar Application of Zinc Sulphate

A field experiment with 60 groundnut cultivars, in a calcareous soil having 1.20 mg kg^?1 available zinc (Zn), foliar application of 0.2% aqueous solution of zinc sulphate thrice at 40, 55 and 70 days at 500, 500 and 1000 L ha^?1, respectively, increased the number of pods, pod yield, shelling and 100 seed mass and seed zinc (Zn) content, significantly. The seeds Zn content in groundnut cultivars ranged 38–70 mg kg^?1 with an average of 48 mg kg^?1 without Zn and 58 mg kg^?1 with Zn. Foliar Zn application increased 22% Zn in seed. This increase was more than 10% in 48 out of 60 cultivars. The cultivars GG 7, GG 20, Tirupati 4, DH 8, JSP 19, TKG 19 A, CSMG 884 and S 206 showed > 50 mg kg^?1 Zn, > 10% increase in seed Zn with Zn application and > 250 g m^?2 pod yield.     

TiO2 Immobilized Biodegradable Polymer for Photocatalytic Removal of Chlorophenol

This study concentrated on the direct immobilization of anatase nano titanium dioxide particles (TiO₂, 44?nm particle size) into or onto a biodegradable polymer, polycaprolactone, by solvent-cast processes. The photocatalytic properties of the produced materials were tested by photocatalytic removal of organic contaminant 4-chlorophenol. Produced TiO₂ immobilized polymer successfully removed 4-chlorophenol (4-CP, 20?ppm which is equal to 1.56?×?10^?4?M) from aqueous solution without additional pH arrangement employing a UV-A light (365?nm) source. Immobilization of n-TiO₂ onto polycaprolactone (PCL) produced improved 4-CP removal percentages, reaching to nearly 85?%. Increased PCL mass significantly increases the removal percentage of 4-CP. When a UVC lamp emitting 254?nm light is used, the removal percentage reaches to 89?%. UV irradiation did not cause any change in the microstructure of the polymeric material (confirmed with ATR-FTIR analysis). This is an important evidence that the material could be reused for further photocatalytic treatments. Produced material seems to be highly promising for successful removal of organic pollutants beside its biodegradable nature.     

Mechanistic Consideration of Zinc Ion Removal by Zero-Valent Iron

Mechanism of zinc iron removal by zero-valent iron was discussed through zinc removal responses to several operational conditions of a packed column reactor with zero-valent iron powder. The adsorption isotherm observed implied that a kind of chemisorption was responsible for zinc removal. Zinc removal by zero-valent iron was enhanced by dissolved oxygen and ferric ion addition. However, it was deteriorated under acidic pH. In addition, zinc adsorbed on zero-valent iron was eluted by a reducing agent such as citric acid, whereas the zinc was not eluted by diluted sulfuric acid. Consequently, the zinc removal mechanism by zero-valent iron was inferred to be as follows: Zero-valent iron was firstly corroded and oxidized into ferric ion by dissolved oxygen. The ferric ion was precipitated as iron hydroxide onto the surface of the zero-valent iron powder. Zinc ion was adsorbed on and/or coprecipitated with the iron hydroxide. The iron hydroxide was finally oxidized and transformed into iron oxides.     

土壤中石油类污染物的化学氧化去除研究

用H2O2氧化处理柴油重度污染土壤,研究了土壤初始含油量、H2O2投加量、土壤pH值以及催化剂等的影响.结果表明,室温条件下向油污土壤中直接投加氧化剂的修复方法可行;H2O2的经济添加量为400 ml/kg土,低含油(20000 mg/kg)污土的去除率可达70.0%以上,高含油(50000 mg/kg)污土的去除率可达96.0%以上:pH 5～8范围内土壤介质对该法的应用影响不大;如用芬顿试剂处理高含油(50000 mg/kg))污土,H2O2只需100 ml/kg土或200 ml/kg土,就能达到85.0%以上的去油效果.     

石灰土壤原状土柱上硼和锌的迁移

Leaching of boron （B） and zinc （Zn） can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied using 8.4 cm diameter × 28 cm long intact columns from two calcareous soil series with differing clay contents and vadose zone structures： Lyallpur soil series, clay loam （fine-silty, mixed, hyperthermic Ustalfic Haplargid）, and Sultanpur soil series, sandy loam （coarse-silty, mixed, hyperthermic Ustollic Camborthid）. The adsorption isotherms were developed by equilibrating soil with 0.01 tool L^-1 CaCl2 aqueous solution containing varying amounts of B and Zn and were fitted to the Langmuir equation. The B and Zn breakthrough curves were fitted to the two-domain convective-dispersive equation. At the end of the leaching experiment, 0.11 L 10 g L^-1 blue dye solution was also applied to each column to mark the flow paths. The Lyallpur soil columns had a slightly greater adsorption partition coefficient both for B and Zn than the Sultanpur soil columns. In the Lyallpur soil columns, B arrival was immediate but the peak concentration ratio （the concentration in solution at equilibrium/concentration applied） was lower than that in the Sultanpur soil columns. The breakthrough of B in the Sultanpur soil columns occurred after about 10 cm of cumulative drainage in both the columns; the rise in effluent concentration was fast and the peak concentration ratio was almost 1. Zinc leaching through the soil columns was very limited as only one column from the Lyallpur soil series showed Zn breakthrough in the effluent where the peak concentration ratio was only 0.05. This study demonstrates the effect of soil structure on B transport and has implications for the nutrient management in field soils.     

Removal of Fluoride from Water by Adsorption onto Lanthanum Oxide

Rare earth mineral based adsorbent viz. lanthanum oxide was investigated for potential application in defluoridation of drinking water for isolated and rural communities. Results of batch experiments indicated about 90% removal in 30 min from a 4 mg L⁻¹ synthetic fluoride solution. The effects of various parameters like contact time, pH, initial concentration, and sorbent dose on sorption efficiency were investigated. Adsorption efficiency was dependent on initial fluoride concentration and the sorption process followed BET model. Variation of pH up to 9.5 has insignificant effect on sorption and beyond a pH of 9.5, the effect was drastic. Among anions investigated, carbonates exhibited high detrimental effect on fluoride adsorption while anions like bicarbonates, chlorides, and sulfates did not seriously affect the process. Adsorbent showed negligible desorption of fluoride in distilled water. Alum was more effective regenerant than HCl and NaOH. Results of cyclic regeneration with alum indicated that the sorbent could be regenerated for ten cycles without significant loss of sorption capacity. Studies with upflow fixed-bed continuous flow columns indicated the usefulness of sorbent for fluoride removal in continuous flow process.     

Graphene Oxide/Alginate Quasi-Cryogels for Removal of Methylene Blue

Quasi-cryogelation technique is a simple yet effective technique for improving the adsorptive efficiency of biopolymer-based adsorbent materials. In this work, a biopolymer-based adsorbent material, graphene oxide alginate quasi-cryogel beads are reported. Alginate biopolymer was crosslinked and frozen at ??21 °C in order to obtain a gel with cryogel-like microstructure. Graphene oxide was included in the bead formulation in order to enhance the adsorptive characteristics. Beads were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and swelling experiments. Removal of the model cationic dye, methylene blue, was studied by batch adsorption method. It is found that the adsorption follows the Freundlich isotherm model and pseudo-first order kinetics with reaching an adsorption capacity of 122.26 mg/g in 60 min. Results indicate that the physisorption might be due to the π–π interactions between graphene oxide and methylene blue, in addition to electrostatic interactions. Moreover, quasi-cryogelation technique significantly improved the dye removal properties.     

Photocatalytic Degradation of Reactive Black 5 by Fish Scale-Loaded TiO2 Composites

Titania and TiO₂/fish scale composites at different mass ratios (90:10, 70:30, and 50:50) were prepared by sol?Cgel method for application as photocatalysts in this study. Fish scale, synthesized TiO₂, and TiO₂/fish scale composites were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), and nitrogen sorption. Their photocatalytic activities were evaluated through the degradation of Reactive Black 5 (RB 5) under solar light irradiation. The effects of irradiation time, catalyst loading, and mass ratios of TiO₂/fish scale composites on the photocatalytic degradation of RB 5 were investigated. The results revealed that the photocatalytic activity of TiO₂/fish scale composites showed compatible and enhanced degradation compared to the synthesized titania.     

Removal of Trinitrotoluene with Nano Zerovalent Iron Impregnated Graphene Oxide

Nano zerovalent iron (nZVI) impregnated reduced graphene oxide (nZVI-rGO) hybrid was prepared via gaseous hydrogen reduction of anhydrous iron(III) chloride (FeCl₃) on the surface of thermally exfoliated reduced graphene oxide (rGO) nanosheets without using any toxic reducing agent, surfactant, or stabilizing agent. Characterization of prepared samples was carried out using various techniques. Morphological study showed that prepared rGO possesses a few-layered wrinkled paper-like structures and nZVI particles of ~?30 nm size were homogeneously dispersed on the surface of rGO nanosheets. Fourier transform infrared (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray spectrometry (EDS) analyses indicated that oxygen-containing functional groups decreased in the order of graphite oxide (GO) > rGO > nZVI-rGO. Removal studies of trinitrotoluene (TNT) were carried out using graphite (G), GO, rGO, and nZVI-rGO with the aid of high-performance liquid chromatography (HPLC). Kinetic models were applied to establish the rate and mechanism of adsorption of TNT on different adsorbents, and intraparticle diffusion model based on initial adsorption characteristics was employed to ascertain mechanism of film and intraparticle diffusion in the adsorption process. The removal rate and adsorption capacity was found to be highest for nZVI-rGO, which renders this adsorbent to be a potential futuristic adsorbent for removal of explosives.

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Graphical Abstract ?

     

DTC类重金属捕集剂对猪场废水中Cu、Zn的去除试验研究

通过黄原酸化反应将二硫代氨基甲酸(DTC)基团引入至壳聚糖,制备DTC类重金属捕集剂,用以去除猪场废水Cu、Zn。结果表明,DTC类重金属捕集剂对Cu、Zn的捕集性能受废水初始p H值和捕集剂投加量的影响,p H值有一个适宜范围,即p H 3.0~5.0;随着捕集剂投加量的增加,去除效果逐渐增加,但增加速率逐渐减缓。捕集剂性能受进水Cu、Zn浓度以及废水温度的干扰不很明显。在废水p H值5.0,捕集剂投加量2.0 g·L-1(废水),初始Cu、Zn浓度25~200 mg·L-1时,捕集剂对Cu、Zn的去除率可达到99%以上,且处理后Cu、Zn浓度低于污水综合排放标准(GB 8978—1996)一级标准限值规定。DTC类重金属捕集剂对Cu、Zn的等温吸附特征可用Langmuir方程进行拟合,其吸附平衡时间约为20 min左右。     

Biofortification of Durum Wheat with Zinc Through Soil and Foliar Applications of Nitrogen

Increasing zinc (Zn) concentration of cereal grains is a global challenge to alleviate Zn deficiency‐related health problems in humans caused by low dietary Zn intake. This study investigated the effects of soil‐ and foliar‐applied nitrogen (N) and Zn fertilizers on grain Zn accumulation of durum wheat (Triticum durum) grown on a Zn‐deficient soil. In addition, localization of Zn and protein within durum wheat grain was studied by using Bradford reagent for protein and dithizone (diphenyl thiocarbazone) for Zn. Grain Zn concentration was greatly enhanced by soil or foliar applications of Zn. When Zn supply was adequately high, both soil and foliar N applications improved grain Zn concentration. Consequently, there was a significant positive correlation between grain concentrations of Zn and N, when Zn supply was not limiting. Protein and Zn staining studies showed co‐localization of Zn and protein within grain, particularly in the embryo and aleurone. Results indicate that N and Zn fertilization have a synergistic effect on grain Zn concentration. Possibly, increasing N supply contributes to grain Zn concentration by affecting the levels of Zn‐chelating nitrogenous compounds or the abundance of Zn transporters. Our results suggest that nitrogen management can be an effective agronomic tool to improve grain Zn concentration.     

Effect of Conditioning Zinc Sulfate Heptahydrate (ZnSHH) with Zinc Oxide (ZnO) and Neem Oil on Growth,Productivity, Zinc Biofortification of Grain and Zinc Uptake by Basmati Rice

Commercial grade zinc (Zn) sulfate hepta hydrate (ZnSHH) is the most widely used source of Zn in India and several other countries for amelioration of Zn deficiency in crops. However, it releases water of hydration at temperature above 30°C and forms lumps on storage, which make it difficult to handle it and apply in fields. Therefore, conditioning of ZnSHH with ZnO and neem oil reduces the release of water of hydration and prevents lumps formation and can be well stored. Field experiments were conducted at the research farm of the Indian Agricultural Research Institute, New Delhi, India during rice growing seasons (July-November) of 2009 and 2010 to study the effect of conditioning ZnSHH with ZnO and neem oil on growth, productivity and Zn fortification of rice (Oryza sativa) grain and uptake by Basmati rice ‘Pusa 1121’. The experiment was conducted in a randomized block design with 3 replications comprised of 9 treatments of Zn fertilization. The present study shows that when conditioned with 2% ZnO and 4% neem oil ZnSHH improved yield attributes, grain and straw yields, Zn uptake and partial factor productivity (PFP), agronomic efficiency (AE), recovery efficiency (RE), and physiological efficiency (PE) of Zn in Basmati rice ‘Pusa 1121’. In general, ZnO was inferior to ZnSHH. Application of ZnSHH conditioned with 2% ZnO and 4% neem oil can be a better source of Zn for transplanted puddled Basmati rice on Zn deficient soils.     

改进型生物过滤器对H_2S和NH_3混合气体去除效果的研究

生物过滤器去除恶臭气体的影响因素包括进气的容积负荷、填料湿度、填料层高度、填料中微生物种群和数量及填料层成分的变化,为进一步了解生物过滤器的去除效果,共设计4个处理组,分别编号为A、B、C和D,用猪粪堆肥、珍珠塔、活性蚯蚓粪和锯末按不同比例组成生物过滤器填料,并添加除臭优势菌种和蚯蚓处理H2S和NH3。结果表明,生物过滤器填料中微生物数量丰富,细菌和真菌在最高的C组分别达到（2.23～3.26）×1010cfu·g-1和（2.00～3.08）×105cfu·g-1。在生物过滤器填料中各种形态氮和硫的分布不均匀,NH4＋-N与S2--S由下向上递减,而NO3--N起初是下部高于上部,但随着运行时间的延长,上部的NO3--N逐渐高于下部。在该生物除臭系统中,用活性蚯蚓粪、堆肥和锯末混合填料（C）处理效果最好,是很好的生物过滤器填料,有存活的蚯蚓,其余3个处理均没有存活的蚯蚓。     

Study of Phosphorus Removal by Using Sponge Iron Adsorption

Phosphorus is one of the key elements causing lake eutrophication. This paper deals with phosphate removal by Sponge iron in batch and fixed-bed operation. Isotherm and kinetic studies are conducted. The isotherm data is described by the Freundlich and Langmuir model, while the kinetic data of adsorption is fitted by the pseudo-second-order kinetic model. The saturated adsorption capacity of Langmuir isothermal equation is about 3.25 mg/g. The concomitant anions have adverse effect on phosphate adsorption and the effects follow the order: NO₃^??>?Cl^??>?SO₄^2?. The phosphate adsorption capacities of SI were improved significantly under the acidic condition. The results of the fixed-bed operation show that, with the increase of the influent phosphate concentrations, the breakthrough curve becomes steeper while the break point time decrease. According to the Adams–Bohart model, the critical height of the column decrease from 0.135 to 0.105 m when the contact time increased from 10 to 30 min with the influent concentration of 1.0 mg/L. According to BDST model, the critical bed depth is 0.15 m when the influent concentration of phosphate is 1.0 mg/L and the contact time (h) is 20 min.     

The Effect of Oxide Coating Dissolution on Cd Transport Through a Natural Quartz Sand

The role of flow rate on Cd transport through a natural aquifer sand was investigated using a laboratory column set-up with particular reference to dissolution processes of external coatings. Clays and (hydr)oxides dissolution was investigated by tests performed feeding the column with Cd-free solutions at three different flow rates (0.2, 1 and 5 mL min^–1). Flow rate significantly affected only the dissolution of Fe-containing coatings by releasing into the liquid phase different amounts of Fe. Cd transport experiments showed a strong effect of flow rate on Cd breakthrough curves and the lowest Cd adsorption was observed at the lowest flow rate. This behavior was fully explained in terms of competition between dissolved Fe and applied Cd for the same adsorption sites. Comparison of the Cd transport behavior on a pure quartz sand allowed confirmation of the strong influence of clay and (hydro)oxide coatings in determining the surface properties of the heterogeneous natural materials. An equilibrium model was proposed to describe the dynamic Cd behavior under the different experimental conditions (flow rates and Cd concentrations).