Heterogeneous Activation of Persulfate by Graphene Oxide-TiO<Subscript>2</Subscript> Nanosheet for Oxidation of Diclofenac: Optimization by Central Composite Design

In this study, the performance of oxidation with actived persulfate (PS) by graphene oxide-TiO₂ nanosheet (GO-TiO₂) was investigated for diclofenac (DCF) removal, an anti-inflammatory analgesic being widely used in human health care and veterinary treatment. GO-TiO₂ containing oxygen functional groups is employed as an activator for the activation of PS used as the oxidizing agent. Modeling and optimization of the process were performed by central composite design (CCD) as a response surface methodology (RSM). The effects of various factors, including PS concentration, GO-TiO₂ amount, initial pH of DCF solution, and reaction time on DCF oxidation, were evaluated. When the estimated values of the full quadratic model obtained with CCD were compared with the actual experimental results, a strong agreement was obtained with an R² value of 0.9553. Besides, the model consistency was verified by analysis of variance (ANOVA) with a value of 20.17 of F value and P value of less than 0.05. After the optimization run, maximum DCF removal of 93.06% occurred with contact time of 14 min, pH of 5.54, PS concentration of 10 g/L, and 0.1 g of GO-TiO₂ as optimal variable values.     

Lubricant base stock potential of chemically modified vegetable oils

The environment must be protected against pollution caused by lubricants based on petroleum oils. The pollution problem is so severe that approximately 50% of all lubricants sold worldwide end up in the environment via volatility, spills, or total loss applications. This threat to the environment can be avoided by either preventing undesirable losses, reclaiming and recycling mineral oil lubricants, or using environmentally friendly lubricants. Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environment friendly lubricants. Lubricants based on vegetable oils display excellent tribological properties, high viscosity indices, and flash points. To compete with mineral-oil-based lubricants, some of their inherent disadvantages, such as poor oxidation and low-temperature stability, must be corrected. One way to address these problems is chemical modification of vegetable oils at the sites of unsaturation. After a one-step chemical modification, the chemically modified soybean oil derivatives were studied for thermo-oxidative stability using pressurized differential scanning calorimetry and a thin-film micro-oxidation test, low-temperature fluid properties using pour-point measurements, and friction-wear properties using four-ball and ball-on-disk configurations. The lubricants formulated with chemically modified soybean oil derivatives exhibit superior low-temperature flow properties, improved thermo-oxidative stability, and better friction and wear properties. The chemically modified soybean oil derivatives having diester substitution at the sites of unsaturation have potential in the formulation of industrial lubricants.     

Effect of nutrient sources on cucumber production in different substrates

The research was conducted in two successive seasons to compare the effect of nutrient sources, organic manure and inorganic conventional nutrient solution, in cucumber production performed with different local substrates. In fall, the experiment was designed to test three factors, namely cultivar [(a) Armada, (b) Gordion], nutrient source [(a) inorganic nutrient solution, (b) solid organic manure] and substrate [(a) 3 + 1 perlite + clinoptilolite, (b) 1 + 1 perlite + clinoptilolite, (c) 3 + 1 tuff + clinoptilolite, (d) 1 + 1 tuff + clinoptilolite, v/v]. Results showed that organic manuring decrease the total yield by 22.4% in comparison to inorganic nutrient solution. In organic manure treatment, vigorous variety (Armada) gave higher yield than less vigorous variety (Gordion). In the spring season, the tested factors were decreased to two and tested as nutrient source [(a) inorganic nutrient solution, (b) solid organic manure, (c) organic nutrient solution] and substrate. Armada was the only cultivar. Compared to that of the inorganic nutrient solution, total yield was reduced by 10.9% in the organic nutrient solution system and 31.3% in solid organic manure treatment.     

Bioremediation and reuse of shrimp aquaculture effluents to farm whiteleg shrimp,Litopenaeus vannamei : a first approach

Shrimp aquaculture effluents were bioremediated in a two‐phase system (System A) using the black clam Chione fluctifraga and the benthic microalgae Navicula sp., and then reused to farm whiteleg shrimp Litopenaeus vannamei. In the experimental design, Systems B and C had an identical structure as System A, but no clams or microalgae were added. System B received the same shrimp effluents while System C received only estuarine water. Shrimp raw effluents had a poor water quality. System A improved the water quality by decreasing the concentrations of total nitrogen, total ammonia nitrogen (TAN), nitrites, nitrates, phosphates, total suspended solids (TSS) and organic suspended solids (OSS). System B also decreased the concentration of TAN, TSS and OSS via sedimentation, but the effect was less pronounced than that observed in System A. Shrimp reared in the bioremediated effluents (System A) had better production (3166 kg ha^?1) and higher survival (89.2%) than those reared in effluents from Systems B (2610 kg ha^?1, 75.1%) and C (2874 kg ha^?1, 82.1%). It is concluded that the bioremediation system was moderately efficient and the bioremediated effluents were suitable to farm L. vannamei.     

Soybean oil based greases: influence of composition on thermo-oxidative and tribochemical behavior

The biodegradable properties and lubricating ability of greases depend on both the base oil and the thickener. Mineral oils are the most widely used lubricant base fluids due to their inherent lubricity and low cost, but recent environmental awareness has forced consideration of the use of biodegradable fluids such as vegetable oils and certain synthetic fluids in grease formulations. This study presents data on the thermo-oxidation behavior and tribology of biodegradable greases formulated with soybean oil and different compositions of metal soap thickener. The composition of thickener has been varied by using fatty acids with different degrees of unsaturation and fatty acids of different chain lengths. The improvement of thermo-oxidation and tribological properties as a result of changing thickener/base oil ratio and the antioxidative effect of some suitable additives have also been evaluated.     

Assessment of Arsenic and Selenium Concentration with Chlorophyll Contents of Sugar Beet (Beta vulgaris var.saccharifera) and Wheat (Triticum aestivum) Exposed to Municipal Sewage Sludge Doses

The present study was conducted to assess the suitability of sewage sludge amendment in soil for Beta vulgaris var. saccharifera (sugar beet) and Triticum aestivum (wheat) by evaluating the arsenic and selenium accumulation and physiological responses of plants grown at 10%, 25%, and 50% sewage sludge amendment rate. Sewage sludge amendment was modified by the physicochemical properties of soil, thus increasing the availability of heavy metals in the soil and consequently with higher accumulation in plant parts. The chlorophyll contents increased after the sewage sludge treatments except for 50%. The sewage sludge amendment led to a significant increase in arsenic and selenium concentrations of the soil. The heavy metal accumulation in the soil after the treatments did not exceed the limits for the land application of sewage sludge recommended by the US Environmental Protection Agency. The increased concentration of heavy metals in the soil due to the sewage sludge amendment led to increases in heavy metal uptake in the leaves and root concentrations of arsenic and selenium in plants as compared to those grown on unamended soil. Accumulation was more in roots than shoots and leaves for most of the heavy metals. Concentrations of arsenic and selenium were more than the permissible limits of national standards in the edible portion of sugar beet and wheat grown on different sewage sludge amendments ratios. The study concludes that the sewage sludge amendment in the soil for growing sugar beet and wheat may not be a good option due to risk of contamination of arsenic and selenium.     

Effect of solarization and fumigant applications on soilborne pathogens and root-knot nematodes in greenhouse-grown tomato in Turkey

A study was conducted in two greenhouses with a history of Fusarium crown and root rot (Fusarium oxysporum f.sp.radicis-lycopersici, Forl) and root-knot nematodes (Meloidogyne javanica andM. incognita). During the 2005–06 growing season, the effectiveness of soil disinfestation by solarization in combination with low doses of metham-sodium (500, 750, 1000 and 1250l ha⁻¹) or dazomet (400 g ha⁻¹), was tested against soilborne pathogens and nematodes in an attempt to find a suitable alternative to methyl bromide, which is soon to be phased out. Solarization alone was not effective in the greenhouse with a high incidence ofForl. In the greenhouse with a low level ofForl, all the treatments tested reduced disease incidence, and were therefore considered to be applicable for soil disinfestation. In addition, root-knot nematode density decreased with all the treatments tested in both of the greenhouses.     

Biobased grease with improved oxidation performance for industrial application

Vegetable oils have significant potential as a base fluid and a substitute for mineral oil for grease formulation. This paper describes the preparation of biobased grease with high oxidative stability and a composition useful for industrial, agriculture/farming equipment, and forestry applications. The process utilizes more oxidatively stable epoxy vegetable oils as the base fluid, metal-soap thickener, and several specialty chemicals identified to address specific applications. Performance characteristics of greases used for industrial and automotive applications are largely dependent on the hardness and the oxidative stability of grease. Grease hardness was determined using standard test methods, and their oxidative stabilities were determined using pressurized differential scanning calorimetry and rotary bomb oxidation tests. Wear data were generated using standard test methods in a four-ball test geometry. Results indicate that grease developed with this method can deliver at par or better performance properties (effective lubrication, wear protection, corrosion resistance, friction reduction, heat removal, etc.) than existing mineral oil-based greases currently used in similar trades. Therefore, developed greases can be a good substitute for mineral oil-based greases in industrial, agriculture, forestry, and marine applications.     

Synthesis of hydroxy thio-ether derivatives of vegetable oil

Bio-based additives are desirable commodities due to their eco-friendly nature. These additives can demonstrate physical and chemical properties comparable to those of conventional mineral oil-based products. Sulfur incorporated triacylglycerol can function as an antiwear/antifriction additive for lubricants. The synthesis of four useful hydroxy thio-ether derivatives of vegetable oils, from commercially available epoxidized soybean oil and common organic thiols, is reported in this paper. The common thiols used herein were 1-butanethiol, 1-decanethiol, 1-octadecanethiol, and cyclohexyl mercaptan. Currently, there is no reported literature describing the synthesis of hydroxy thio-ether derivatives of vegetable oil. The reaction was monitored, and products were confirmed by NMR and FTIR spectroscopies. Experimental conditions involving various thiols, solvent, catalyst amount, time, and temperature were optimized for research quantity and laboratory scale-up. The synthetic process retains the vegetable oil structure, eliminates polyunsaturation in the molecule, and adds polar functional groups on triacylglycerol. These products can be used as agriculturally-based antiwear additives for lubricant applications.