Search results

This paper aims to report a novel preparation method of ZnO particles with different structures and their photocatalytic activity.

ZnO powders are prepared by a facile, economical and environment-friendly aqueous solution route. X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy and UV-vis diffuse reflectance spectra are used to characterize the products. Photocatalytic activity of the samples is evaluated by degradation of organic pollutant pentachlorophenol under UV-vis irradiation.

It is found that three-dimensional ZnO hierarchical structures can be prepared via aqueous solution route without using any template or structure-directing agent, and the alkalinity of reaction solution is the key factor. All the as-prepared ZnO products have good catalytic activity under UV-vis light irradiation.

This report presents a simple method for the preparation of ZnO particles with excellent photocatalytic activity. Experimental results could provide useful reference for the treatment of chlorophenols in the future.

The purpose of this paper is to assess the ground water quality and salinity issues in the fast developing coastal urban lands of two river basins of Thiruvananthapuram district, Kerala, South India.

In order to address the water quality of the basins, field sampling was conducted and the samples were analysed in the laboratory. A comparison with water quality standards was also made and the interpretations of the results were done using GIS and statistical tools.

The values of conductivity, chlorides and salinity show that the coastal areas of Neyyar and Karamana basins are severely affected by salinity intrusion in addition to the pollution problems. More than 90 per cent of the samples are with hardness lower than 100 mg/l. About 70 per cent of the study area is with calcium concentrations lower than 25 mg/l. The content of sulphate and magnesium in Poovar and Poonthura coastal stretches is found to be higher compared to other regions.

Since not much work has been published from the study area on these aspects, the hydrochemical characterization is a very important in deciphering the quality of ground water for its proper management. The water quality evaluation and salinity intrusion studies are very important for the future planning and development of this area.

The removal of Ismative SHR blue (reactive dye) using a very cheap cement factory waste called by‐pass kiln dust has been investigated in batch mode. The effects of initial dye solution concentration, particle size, agitation rate, amount of by‐pass kiln dust, and dye solution temperature were studied. A 95.5 per cent removal was achieved. Some pretreatment of by‐pass kiln dust, such as washing by distilled water or rinsing with HCL solution, has been done. By using the washed by‐pass kiln dust the values of total dissolved solids, alkalinity, and efficiency of colour removal were reduced. A very rapid irreversible chemical reaction may occur in addition to the adsorption process. Ferric chloride was used as a coagulant after settling to complete the separation of the dust from the clear solution. A removal of 96 per cent from the initial colour of the industrial coloured wastewater was achieved.

The present study aims to determine the residue levels in the soil and water prior to, and after fertilization, as previous soil investigations in Kuwait indicated that different types of fertilizers are used leaving residues in the soil, in order to assist the prospective farmers in choosing environmental sound chemicals for each crop. The importance of the following is to determine the geologic conditions of the soil in such a productive farm area and the effect of the use of fertilizers.

To achieve the study purpose soil and water samples were collected over a wide area and chemical parameters (pH, electrical conductivity (ECe), cations (Ca⁺², Mg⁺²), and anions (CO₃⁻²,HCO₃⁻,Cl⁻)) were obtained via the suitable and most appropriate chemical analyses.

The soils have several levels of calcareous contents along with varying salinity and alkalinity. Before fertilization on average, soil ECe ranges from 0.93 to 4.37 mS/cm, pH from 7.4 to 7.60, cations 8.00 to 36.00 meq/l, and anions from 4.85 to 29.61 meq/l. After fertilization pH ranges from 7.09 to 7.47, ECe ranged from 3.79 to 12.85 mS/cm, cations ranges from 29.75 to 66.36 meq/l, and anions ranges from 15.18 to 63.32 meq/l; showing that ECe, cations and anions average values has increased by almost three to four orders of magnitude. Furthermore, ECe, pH, cations, and anions values have sharply increased with depth. The evidence from this study shows that vertical leaching adversely contributes to the deterioration of the groundwater quality and rate.

The output of this study is intended to be the building block or the nuclei for a data bank on the prevailed agricultural practices in different aspects, and upon which further studies on the southern area of Kuwait will depend.

The farm areas in the southern region of Kuwait state (case study: Al‐Wafrah farms) suffer from misuse and mismanagement of the agricultural lands in different aspects. This paper provides new source of information on the historical record of farm development and the nature, performance and results of the associated agricultural practices in such areas, as so to be the base or the starting point form which further studies can go forth.

This paper aims to evaluate the effect of precursors on the anticorrosion property of silica encapsulated waterborne aluminium pigments (WBAPs).

The silica encapsulated WBAPs were prepared using different siloxanes as precursors. The anchorage and compactness of silica films on aluminium flakes were characterized by optical microscopy, scanning electron microscopy and N2 adsorption-desorption. The anticorrosion property and glossiness of WBAPs were evaluated.

The effect of precursors on anticorrosion property of silica encapsulated WBAPs is reflected from the anchorage and the compactness of silica on aluminium flakes surface. Furthermore, the structure of γ-aminopropyl triethoxysilane benefits the anchorage and the compatibility between pigment and acrylic resin. Neither high nor low ratio of tetraethoxysilane/γ-aminopropyl triethoxysilane is favourable to the anchorage and formation of dense silica film on the aluminium flakes surface. To obtain perfect WBAP, the precursors of silica must be carefully selected.

Only four kinds of precursors were used in this work; other precursors could also be studied.

The investigation results provide theoretical basis to obtain excellent WBAPs.

The method to investigate anticorrosion property of WBAPs that is based on the effect of precursors on the performance of silica was novel.

The purpose of this paper is to explore the long‐term corrosion behavior of carbon steel in 3% NaCl solution and evaluate the effect of rust layer on the corrosion process.

The corrosion behavior of rusted carbon steel in 3% NaCl solution was studied by means of infrared spectroscopy (IR) and electrochemical impedance spectroscopy (EIS).

The results indicated that the corrosion of carbon steel was affected by chloride ion in initial immersion and then controlled by the rust layer. The rust layer consisted of a thin outer layer (γ‐FeOOH layer) and a thick inner layer (Fe₃O₄ layer). The outer rust layer facilitated the cathodic process via reduction of γ‐FeOOH, while the inner rust layer provided a large cathode area and oxygen could be reduced on its surface. As a result, the corrosion rate of carbon steel was determined by the limiting diffusion rate of oxygen and stabilized at a high value.

The corrosion model of rusted carbon steel in 3% NaCl solution was established. It is probable that the iron rust in all slightly acidic water with low alkalinity can promote the corrosion process via reduction of γ‐FeOOH. Anti‐corrosion measures for iron in this type of solutions should be aimed to reduce the promoting effect of rust layer on the metal corrosion. The NaCl solution prepared from tap water is more suitable for the substitution of artificial water than that prepared from deionized water.

A. General Damage to boiler plants and heating installations results mainly from the action of oxygen dissolved in the water, from free carbon dioxide and boiler scale formed from the hardness of the water. More detailed information regarding the softening and dealkalisation of boiler feed water can be found in the relevant literature describing our Lewatit ion exchange resins, which we will be pleased to supply on request.

In this study, alkali calcium sulfonate which is added to engine oils as a detergent‐dispersant was obtained. A definite amount of Ca(OH)₂ and water was added to the mixture of neutral calcium sulfonate (NCS) and spindle‐oil (SO), and the mixture was taken into an appropriate reactor. CO₂‐air mixture was passed through the mixture for definite periods at 85°C and the appropriate parameters affecting the qualities and efficiency of the product were determined. Thus, after the mixture of CO₂+air (having the ratio of 1/8.5) was passed through the mixture of 180 g NCS+600 g SO+60 g Ca(OH)₂+90 g water with the velocity of 108 L/h for 200 min, transparent alkali calcium sulfonate with a total base number value of 28.6 mg KOH/g was obtained.

Water used for large‐scale domestic and industrial purposes generally requires treatment in various ways. When heavily charged with suspended matter, a pre‐filtration process of sedimentation is necessary. Chemical reagents are added to correct over‐hardness, softness, acidity or alkalinity and to form a flocculent precipitation on the surface of the filtering medium in order to trap over 95% of the bacteria and other matter in suspension minute enough to pass through the filtering medium. Chlorine is added as required for sterilisation purposes.

The purpose of this paper is to investigate the physico-chemical properties of the groundwater surrounding the Solous (solid waste dumpsite) at Isheri, Lagos, Nigeria.

In total, 40 groundwater samples were collected from ten pre-determined sampling stations. Three sample stations were established before the dumpsite; three sample stations were located in the vicinity of the dumpsite in the direction of the leachate plume, while the remaining four sample stations were situated further away and acted as a control. Sampling was carried out four times during the study period (twice each in the rainy and dry seasons). The parameters measured in situ were air and water temperatures (using mercury-in-glass bulb thermometer) and pH (using pH meter). Calcium and magnesium contents were measured using the Ca-Mg indicator; sodium content was measured using the flame emission spectrophotometry and phosphate was measured using the flame photometry. The selected heavy metals (copper, iron, lead, cadmium, zinc and manganese) were measured by using the atomic absorption spectrometer. The oxygen parameters, such as dissolved oxygen, biological oxygen demand, chemical oxygen demand and organic matter, were determined titrimetrically. The data obtained were subjected to descriptive statistics and analysis of variance (ANOVA).

The results showed that many parameters had higher values in the dry season than in the rainy season. Temperature (27.75±0.95°C), alkalinity (211.37±82.78 mg/LCaCO₃), phosphate (0.30±0.07 mg/L) and sulfate (2.78±0.35 mg/L), sodium ion (41.95±18.86 mg/L), dissolved oxygen (2.98±0.57 mg/L) and COD (33.54±4.50 mg/L) had higher mean values in the dry season than in the rainy season. On the other hand, the mean values of electrical conductivity (1,224.85±370.63), nitrate (0.01±0.003 mg/L), chloride (98.76±21.58 mg/L), calcium ion (5.38±0.68 mg/L), magnesium ion (3.05±0.05 mg/L), BOD (22.37±2.20 mg/L) and pH (6.31±0.18) were higher in the rainy season than in the dry season. The heavy metals (iron 1.10±0.05 mg/L, lead 0.12±0.07 mg/L, manganese 0.01±0.004 mg/L, copper 0.15±0.003 mg/L, zinc 0.07±0.004 mg/L and cadmium 0.02±0.02 mg/L) were fairly uniform all year round. There was also a marked decline in the values as one moved away from the dumpsite.

The implication of the findings is that human health is remarkably dependent upon safe and clean drinking water. Preserving the water resources and hindering them from pollution is preferred to the treatment of polluted water and rendering it suitable for consumption. The high electrical conductivity values obtained in the groundwater samples near the dumpsites are an indication of the effect of leachate on the groundwater quality. The high concentrations of dissolved solids in the groundwater may decrease the palatability and may cause gastro-intestinal irritation in humans, and laxative effect particularly on transits.

The pollutants from the various waste components disposed at the dumpsite percolate into the ground to pollute the groundwater. The groundwater is transported in the line of flow away from the vicinity of the dumpsite to pollute the groundwater in the area. The extent of contamination level of groundwater quality due to leachate percolation depends upon a number of factors like chemical composition of leachate, rainfall, depth and distance of the well from the dumpsite. Groundwater samples of different depths and distances from dumpsites were analyzed in the present study to understand the level of a combination.