Polyvinyl chloride (PVC) and ammonio methacrylate copolymer (Eudragit RS 100) were used as models in binary mixture tablets of direct compression study. Eudragit RS 100 is a copolymer synthesized from acrylic and methacrylic acid esters with a low content of quaternary ammonium groups. Combination of PVC and Eudragit RS 100 of different polarities and knowing the surface free energy values allow the possibility of predicting the tensile strength of the tablets. Specimens of 500 mg in the form of thin plates (25 mm x 12.5 mm), were made by compressing each powder at 20 000 MP a compression pressure using a special punch and die set. A Howden Universal Testing Machine was used to compress the powder. Contact angle measurements of the samples were carried out using a Wilhelmy balance, ran by a Cahn Dynamic Contact Angle Machine while different test liquids media such as water, glycerol, formamide and PEG 200 were used in the study. The surface free energy values of the solid materials were calculated using Wu's equation. The results showed large differences between the advancing and receding contact angle values for both materials when tested with glycerol: PVC (0) and PVC (0,) were 93.2 and 65.24 while Eudragit RS 100 (0) and Eudragit RS 100 (0) were 94.56 and 68.18 respectively. The surface free energy values for PVC using PEG 200-glycerol liquid pair were Is: 38.01, ysci: 33.42, ysP: 4.59 and for Eudragit RS 100 using formamide-glycerol liquid pair were ys: 75.03, yd: 51.66, ysP : 23.37, respectively. The results showed harder solid material like Eudragit RS 100 had higher surface free energy compared to elastic material like PVC.
Cyanide is highly toxic to the living organisms as it inhibits respiration system in the cell mitochondria. Cyanide is commonly used in gold extraction process and its discharge into the environment not only causes pollution but it also brings harm to the surrounding population. Chemical treatment is expensive and the use of hazardous compound can exacerbate the problem. Biodegradation offers cheap and safe alternative as it overcomes the problems faced by chemical treatment. In this study, indigenous bacteria from mining wastewater were isolated. Cyanide degradation was done via shake flask method. A bacterium, designated W2 was found able to grow in the mining wastewater. 16S rRNA analysis identified the strain as Pseudomonas pseudoalcaligenes which could tolerate up to 39 mg/L cyanide concentration and growth was depleted at 52 mg/L. 60% cyanide degradation was achieved in wastewater containing medium. End-product analysis from high performance liquid chromatography (HPLC) detected formamide implicating the role of cyanide hydratase in cyanide degradation. It can be concluded that P. pseudoalcaligenes is capable of biodegrading cyanide and its potential in wastewater treatment containing cyanide is feasible.