Tjoon Tow Teng

Removal of dyes and industrial dye wastes by magnesium chloride

Magnesium chloride, as compared to alum and polyaluminium chloride (PAC) is a less commonly used coagulant in the field of wastewater treatment, with a cost in between alum and PAC. It has been used in this study as a coagulant to investigate the eAectiveness in the chemical precipitation method for the removal of colouring matters. The colour concentration of dye solutions was measured by visible spectrophotometry. Parameters such as the eAect of pH, the eAect of coagulant and coagulant aid dosages and the eAect of diAerent coagulants have been studied. The results show that MgCl2 is capable of removing more than 90% of the colouring material at a pH of 11 and a dose of 4 g MgCl2/l of dye solution. MgCl2 is shown to be more eAective in removing reactive dye than alum and PAC in terms of settling time and amount of alkalinity required. Optimal operating conditions such as pH value, coagulant dose and eAect of polyelectrolyte have been determined. Wastewaters of a dyeing and printing mill on diAerent days have been treated by MgCl2 aqueous solution in bench scale. The treatment of the industrial waste has shown a reduction of 88% in COD and 95% of suspended solids. # 1999 Elsevier Science Ltd. All rights reserved

Densities, excess molar volumes, and partial molar volumes for binary mixtures of water with monoethanolamine, diethanolamine, and triethanolamine from 25 to 80°C

We have measured densities of binary mixtures of water with monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) over the full range of compositions and over the temperature range from 25 to 80°C. Results of these measurements have been used in calculating excess molar volumes and partial molar volumes. Knowledge of the volumetric properties of these mixtures is useful in connection with industrial treatment of acidic gases; derived excess molar volumes and partial molar volumes can be used as a basis for understanding some of the molecular interactions in water-organic mixtures.

Extraction and recovery of methylene blue from industrial wastewater using benzoic acid as an extractant.

Liquid-liquid extraction (LLE) of methylene blue (MB) from industrial wastewater using benzoic acid (extractant) in xylene has been studied at 27 degrees C. The extraction of the dye increased with increasing extractant concentration. The extraction abilities have been studied on benzoic acid concentration in the range of 0.36-5.8x10(-2) M. The distribution ratio of the dye is reasonably high (D=49.5) even in the presence of inorganic salts. Irrespective of the concentration of dye, extraction under optimal conditions was 90-99% after 15 min of phase separation. The extracted dye in the organic phase can be back extracted into sulphuric acid solution. The resultant recovered organic phase can be reused in succeeding extraction of dye with the yield ranging from 99 to 87% after 15 times reused, depending on the concentration of the initial feed solution. Experimental parameters examined were benzoic acid concentration, effect of diluent, effect of pH, effect of initial dye concentration, effect of equilibration time, various stripping agents, aqueous to organic phase ratio in extraction, organic to aqueous phase ratio in stripping and reusability of solvent.

Extraction of Cu(II) from aqueous solutions by vegetable oil-based organic solvents

Various types of vegetable oil-based organic solvents (VOS), i.e. vegetable oils (corn, canola, sunflower and soybean oils) with and without extractants (di-2-ethylhexylphosphoric acid (D2EHPA) and tributylphosphate (TBP)), were investigated into their potentiality as greener substitutes for the conventional petroleum-based organic solvents to extract Cu(II) from aqueous solutions. The pH-extraction isotherms of Cu(II) using various vegetable oils loaded with both D2EHPA and TBP were investigated and the percentage extraction (%E) of Cu(II) achieved by different types of VOS was determined. Vegetable oils without extractants and those loaded with TBP alone showed a poor extractability for Cu(II). Vegetable oils loaded with both D2EHPA and TBP were found to be the most effective VOS for Cu(II) extraction and, thus, are potential greener substitutes for the conventional petroleum-based organic solvents.

Adsorption Studies of Methylene Blue and Malachite Green From Aqueous Solutions by Pretreated Lignocellulosic Materials

Lignocellullosic materials have been used as low-cost adsorbents for the removal of methylene blue (MB) and malachite green (MG) dyes from aqueous solutions. The organic compounds in the adsorbents that contribute to chemical oxygen demand (COD) have been removed through pretreatment of the adsorbents. The percentage of color removal and COD reduction of both MB and MG dyes were found relatively close in values. The adsorption process followed the Langmuir isotherm as well as the Freundlich isotherm and pseudo-second order kinetic model. The process was found to be endothermic in nature.

Titanium-based nanocomposite materials: A review of recent advances and perspectives

This article explains recent advances in the synthesis and characterization of novel titanium-based nanocomposite materials. Currently, it is a pressing concern to develop innovative skills for the fabrication of hybrid nanomaterials under varying experimental conditions. This review generally focuses on the adsorption behavior of nanocomposites for the exclusion of organic and inorganic pollutants from industrial effluents and their significant applications in various fields. The assessment of recently published articles on the conjugation of organic polymers with titanium has revealed that these materials may be a new means of managing aquatic pollution. These nanocomposite materials not only create alternative methods for designing novel materials, but also develop innovative industrial applications. In the future, titanium-based hybrid nanomaterials are expected to open new approaches for demonstrating their outstanding applications in diverse fields.

Biological kinetics evaluation of anaerobic stabilization pond treatment of palm oil mill effluent.

Biological kinetic (bio-kinetic) study of the anaerobic stabilization pond treatment of palm oil mill effluent (POME) was carried out in a laboratory anaerobic bench scale reactor (ABSR). The reactor was operated at different feed flow-rates of 0.63, 0.76, 0.95, 1.27, 1.9 and 3.8l of raw POME for a day. Chemical oxygen demand (COD) as influent substrates was selected for bio-kinetic study. The investigation showed that the growth yield (Y(G)), specific biomass decay (b), maximum specific biomass growth rate (mu(max)), saturation constant (K(s)) and critical retention time (Theta(c)) were in the range of 0.990 g VSS/g COD(removed) day, 0.024 day(-1), 0.524 day(-1), 203.433 g COD l(-1) and 1.908 day, respectively.

Screening of factors influencing Cu(II) extraction by soybean oil-based organic solvents using fractional factorial design.

This study aimed to identify the significant factors that give large effects on the efficiency of Cu(II) extraction from aqueous solutions by soybean oil-based organic solvents using fractional factorial design. Six factors (mixing time (t), di-2-ethylhexylphosphoric acid concentration ([D2EHPA]), organic to aqueous phase ratio (O:A), sodium sulfate concentration ([Na(2)SO(4)]), equilibrium pH (pH(eq)) and tributylphosphate concentration ([TBP])) affecting the percentage extraction (%E) of Cu(II) were investigated. A 2(6-1) fractional factorial design was applied and the results were analyzed statistically. The results show that only [D2EHPA], pH(eq) and their second-order interaction ([D2EHPA] × pH(eq)) influenced the %E significantly. Regression models for %E were developed and the adequacy of the reduced model was examined. The results of this study indicate that fractional factorial design is a useful tool for screening a large number of variables and reducing the number of experiments.

Treatment of Terasil Red R Dye Wastewater using H2O2/pyridine/Cu(II) System

The H(2)O(2)/pyridine/Cu(II) advanced oxidation system was used to assess the efficiency of the treatment of a 1 g L(-1) Terasil Red R dye solution. This system was found to be capable in reducing the concentration of chemical oxygen demand (COD) of the dye solution up to 90%, and achieving 99% in decolorization at the optimal concentration of 5.5mM H(2)O(2), 38 mM pyridine and 1.68 mM Cu(II). The final concentration of COD was recorded at 117 mg L(-1) and color point at 320 PtCo. Full 2(4) factorial design and the response surface methodology using central composite design (CCD) were utilized in the screening and optimization of this study. Treatment efficiency was found to be pH independent. The amount of sludge generation was in the range of 100-175 mg L(-1) and the sludge produced at the optimal concentration was 170 mg L(-1).

Design of experiments for Malachite Green dye removal from wastewater using thermolysis – coagulation–flocculation

Abstract Thermolysis – coagulation–flocculation was used for reduction of colour and chemical oxygen demand (COD) of aqueous basic dye Malachite Green. Statistical design of experiment was used for thermolysis experiments which resulted of 69.57% and 70.59% maximum reduction of COD and color, respectively at the optimum conditions of 95 min treatment time, 82°C treatment temperature, and pH 11.02. MgCl2 was used as coagulant for coagulation–flocculation. About 98% of color and 90% of COD were reduced at a final pH of 10.89 and a coagulant dose of 3 g MgCl2 l−1 of dye solution. The optimum conditions for coagulation–flocculation process were determined by varying a single factor while keeping other factors fixed at a specific set of conditions. Coagulation–flocculation after thermolysis at the optimal operating conditions resulted in a reduction of 91.26% COD and 98.78% color at final pH 10.89 but at a much lesser coagulant dosage of 500 mg l−1. Compared to only coagulation–flocculation, combined process o...