Muhammad Zafar

Potato Starch as a Coagulant for Dye Removal from Textile Wastewater

Wastewater from textile industry contains a number of pollutants which are hazardous in nature. The direct discharge of the wastewater into the environment affects its ecological status by causing various undesirable changes. As environmental fortification becomes a global anxiety, industries are finding novel solutions for mounting low-cost and environmental-friendly technologies for the dye removal from the waste. The presence of the dyes hinders sunlight penetration and disturbs the ecosystem of water. However, the treatment of wastewater with biodegradable polymer attains a vital importance as they are environmental friendly. The main objective of the work was to make an effort to develop a feasible process for the removal of dyes/color from the textile wastewater by using potato starch, which is a plant-based bio-polymer. A three-level, full-factorial design was selected, and experiments were conducted using a jar test apparatus. The main effects and interactions of dosage, pH, and temperature on the percentage color removal were analyzed. Reduction in color was analyzed using UV-2800 spectrophotometer. A three-way significant interaction was observed. However, dosage is found to be the most important parameter for dye removal using potato starch.

Nanoindentation Response of Scratched Polymeric Surfaces

The effects of imposed strains on the polymeric surfaces during scratching on the material deformation below the visible surface have not been reported in the literature. The major concern for the polymeric surfaces is the problems related to the effective sectioning for imaging/scanning unlike metal and ceramics. This article describes an experimental qualitative methodology, based on nanoindentation data, to analyze subsurface deformations of polymers resulting from scratch deformations. Poly(styrene), a brittle polymer, poly(methylmethacrylate), a ductile polymer, and poly(etheretherketone), a semicrystalline polymer, were selected for the present study. Nanoindentation responses of the scratched poly(styrene), the scratched poly(methylmethacrylate), and the scratched poly(etheretherketone) surfaces were analyzed with emphasis on the detection of subsurface crazing damage. The polymers were scratched using a 900 conical indenter on a pendulum sclerometer. The scratched polymeric surfaces were assessed using scanning electron microscopy (SEM). The polymeric surfaces were observed to be deformed by a well-known ductile ploughing mechanism. The deformed polymeric surfaces were indented using an MTS Nanoindenter. The data show that the hard asperity scratching initiates subsurface damage, which may tentatively lead to the development of subsurface voidage or crazing in certain areas of the deformed polymers, particularly within the base of the scratch groove. Major conclusions of the work are that the nanoindentation of damaged polymeric surfaces provides a qualitative methodology to estimate the subsurface damage and craze formation. This methodology is important in the context of polymers where conventional effective sectioning of the damaged surface to analyze the subsurface deformations might not be possible.

Scaling in Electrical Conductivity Measurements and Rheological Measurements of Monarch 700 Dispersions Stabilized by Polymers

For making stable dispersions of graphitic carbon black (Monarch 700), the effectiveness of three dispersants/polymers (hypermer LP1, hypermer B246, and OLOA 11000) in xylene is investigated. Hypermer LP1 (polyhydroxystearic acid) is a homopolymer and hypermer B246 (PEG 30-dipolyhydroxystearate) is a polyhydroxystearic acid/polyethylene oxide/polyhydroxystearic acid ABA block copolymer, while OLOA 11000 (polyisobutylene succinimide) has a polar head group (polyamine) attached to a hydrocarbon chain (polyisobutylene). Well-dispersed graphitic carbon black dispersions were prepared using dispersants at optimum concentrations. Percolation threshold and rheological threshold were determined by analyzing the variations in electrical conductivity and elastic modulus with concentration of carbon black. Above threshold concentration, scaling law was applied to experimental data of rheology (dynamic measurements) and electrical conductivity measurements to evaluate quality of the system. Effectiveness of polymers was investigated on the basis of value of critical exponent (t and t′, respectively) in scaling power law. Hypermer LP1 was proved to be a poor dispersant for Monarch 700 dispersions while other two polymers were found to be effective stabilizers.

Atomic Force Microscopy of Polymer Coated Graphitic Carbon Surfaces

A modified AFM technique was used to measure interactions between graphitic carbon black particles and, hence, compare effectiveness of dispersants for stable dispersions. The carbon black dispersions were prepared in water using three polymeric dispersants Triton X100, Triton X405 and Lugalvan BNO12. The surfactants were selected based on a previous study with PE/F103 without aromatic ring. That surfactant had attractive interactions emphasizing need for aromatic ring in anchoring group. Attractive interactions between surfaces were observed in water and in absence of polymers. Lack of any attractive interactions in the presence of polymers proved that the selected dispersants are effective stabilizers.

Adsorption and Rheology of Graphitic Carbon Black Nonaqueous Dispersions Prepared Using Nonionic Surfactants

Rheological and conductivity measurements are reported to investigate the dispersibility of graphitic carbon black dispersions selected as a model for carbon nanotubes. The effectiveness of three dispersants in nonpolar organic solvents were investigated namely polyhydroxystearic acid (Hypermer LP1), PEG 30-dipolyhydroxystearate (Hypermer B246), and polyisobutylene succinimide (OLOA 11000). Hypermer LP1 is homopolymer and Hypermer B246 is polyhydroxystearic acid/polyethylene oxide/polyhydroxystearic acid ABA block copolymer while OLOA 11000 has polar head group (polyamine) attached to a hydrocarbon chain (polyisobutylene). Two nonpolar organic solvents decalin and xylene were selected for the present work. The experimentally determined relative viscosity as a function of effective volume fraction Φ′ curves were compared with the theoretical curves calculated using Kreiger-Dougherty equation for the hard sphere dispersions. The comparison showed that Hypermer B246 and OLOA 11000 dispersions in xylene could be prepared at somewhat higher solid fraction than those dispersions stabilized by Hypermer LP1. Also Hypermer LP1 dispersions do not agree with the Kreiger-Dougherty equation curve, which showed that Hypermer LP1 is not an effective stabilizer. In oscillatory measurements, high values of storage and loss modulus at high volume fractions were obtained indicating strong repulsive interactions between the carbon black particles using Hypermer B246 and OLOA 11000. The dispersions prepared using these surfactants showed lower electrical conductivity as compared to other dispersions prepared without dispersants. Also higher relative conductance was obtained in case of dispersions made by Hypermer LP1 as compared to other dispersions made by Hypermer B246 and OLOA 11000.