Ling Wei Low

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.

Optimization of nickel removal using liquid-liquid extraction and response surface methodology

Abstract The nickel extraction efficiency by means of liquid–liquid extraction (LLE) method was studied using response surface methodology; six parameters were identified as influential factors on nickel removal efficiency as the response. However, on screening experiments, only two factors were selected: pH and di-(2-ethylhexyl) phosphoric acid (D2EHPA) concentration. Face-centered composite design (FCCD) was applied in order to determine the optimum conditions for nickel removal by LLE. The results of FCCD showed that a second-order model described the relationship between the factors and nickel removal properly. Results showed that the optimum conditions are pH 1.1 and D2EHPA concentration 0.2 M, where 95.57% of nickel removal was achieved.

Chemical Modification of Imperata cylindrica Leaf Powder for Heavy Metal Ion Adsorption

Imperata cylindrica leaf was used as raw material to prepare two different adsorbents through chemical modification by using sulfuric acid and phosphoric acid. These two adsorbents, sulfuric acid-modified I. cylindrica leaf-based adsorbent (SIC) and phosphoric acid-modified I. cylindrica leaf-based adsorbent (PIC), were used to adsorb nickel ions (Ni2+) from aqueous solutions. The I. cylindrica leaf-based adsorbent and modified I. cylindrica leaf-based adsorbents were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Different operational parameters such as initial solution pH, adsorbent size, adsorbent dosage, initial Ni2+ ion concentration, and temperature were studied. The adsorption isotherm and the adsorption kinetics were studied systematically. Based on the FT-IR spectrum before and after adsorption of Ni2+ ions, the adsorption mechanism involved both ion exchange and complexation between Ni2+ ions and functional groups on the surface of adsorbents. There was no sulfur and phosphorus detected in the aqueous solutions after adsorption. Therefore, SIC and PIC are effective in adsorbing Ni2+ ions and will not cause secondary pollution to the environment.

Removal of Dyes and Pigments from Industrial Effluents

Dyes are widely used in food, cosmetic, pharmaceutical, printing, textile, and leather industries during manufacturing process. As a result, a considerable amount of undesired coloured effluents is generated. The presence of dyes and pigments in water resources not only renders them aesthetically unacceptable, but also poses serious health-risk factors on living organisms and the environment. Therefore, it is essential to remove such dyes before discharging them into natural water streams. A technically effective and cost-effective treatment method is needed. Removal of parameters such as colour, chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total organic carbon (TOC) from dye containing industrial effluent have become the present topics of research. A wide range of treatment techniques have been explored, including (1) physical treatment (ion exchange, adsorption, etc.), (2) chemical treatment (oxidative processes, coagulation and precipitation, etc.), (3) biological treatment (aerobic, anaerobic, etc.), (4) thermal treatment (thermolysis, wet oxidation, etc.), and (5) combined treatment (adsorption/coagulation, coagulation-flocculation/nanofiltration, etc.), some of which have been applied in some industries’ wastewater treatment process. Current trends and efficient treatment technologies for dyes and pigments wastes are discussed and their strengths and weaknesses are to be compared.

Adsorption of Rhodamine B Dye on Elaeis guineensis Frond Fiber

Adsorption of Rhodamine B (RB) dye was investigated using raw Elaeis guineensis frond fiber (EGFF). Experiments were performed using face centered composite statistical design with six input parameters namely pH (2-10), agitation speed (150-300 rpm), initial dye concentration (100-500 mg/L), temperature (27-80°C), contact time (10-40 min), and adsorbent dosage (0.5-1.5 g). Particle size of < 45 μm was taken as a fixed input parameter. Regression analysis showed good fit of the experimental data to the second-order polynomial model with coefficient of determination (R2) value of 0.99 and 0.98 for color removal and chemical oxygen demand (COD) reduction, respectively. Two optimum operating conditions for the adsorption of RB were found using RSM, resulted in > 99% of color removal and > 97% of COD reduction. The adsorption process was rapid and fitted to the pseudo-second-order kinetic model, while equilibrium data were favorably described by the Langmuir isotherm. The adsorbent showed excellent reusability with 0.1 M NaOH solution as desorbing agent. The findings make EGFF a promising and low-cost adsorbent for the removal of RB from aqueous solutions.

Optimization of the column studies into the adsorption of basic dye using tartaric acid-treated bagasse

AbstractPrevious batch studies have shown that acid treated bagasse is a potentially useful adsorbent for treating dye wastewaters. The present paper examines the use of tartaric acid-modified bagasse for the continuous adsorption of methylene blue (MB) dye in columns. The adsorbent was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. A 23 full factorial design analysis was carried out to screen the significant parameters that affecting the adsorption of MB dye onto tartaric acid-modified bagasse, namely initial MB concentration (100–300 mg/L), column bed height (40–80 mm), and feed flow rate (5–15 mL/min). The adsorption process was optimized using response surface methodology -central composite design with the help of Minitab® 14 software. Maximum decolorization (99.42%) and chemical oxygen demand reduction (88.40%) could be achieved at 200 mg/L inlet MB dye concentration with 78 mm bed height and 3.5 mL/min of feed flow rate. Thomas and Yoon–Nelson models we...

Heavy Metal Ion Extraction Using Organic Solvents: An Application of the Equilibrium Slope Method

The separation procedure of a chemical species from a matrix is essentially based on the transportation of the solute between the two involved phases, generally an organic and an inorganic one. Specifically, solvent extraction uses the concept of unique solute distribution ratios between two immiscible solvents. However, there are several situations where solutes have been observed to completely move from the inorganic to the organic phase (Anthemidis and Ioannou, 2009).