Open Access Short Research Article

Optimization of Recovery Process of Silver from Obsolete Printed Circuit Boards (PCBs)

Olusola Adesina, Ajetunmobi Akeem, Okewale Akindele

Chemical Science International Journal, Page 1-8
DOI: 10.9734/CSJI/2017/20034

Aims: The aim of this work was to optimize the Silver recovery from Printed Circuit Boards (PCBs) of waste computers using statistical method by varying various parameters affecting the recovery.

Methodology: A total of 50 experimental runs was generated using central composite design, these were designed to study the effect viz; Thiourea conconcentration, H2SO4 conconcentration, Temperature, Particle diameter and time. Optimization was carried out using response surface methodology and validation of the result was also carried out.

Results: Statistically significant quadratic model was obtained. A quadratic model predicted the optimum silver recovery of 66.01% at optimal condition of thiourea concentration, 0.01 g/ml, sulphuric acid concentration, 0.01 M, particle size, 0.027 mm, temperature, 20°C and time of 60 min. The optimal condition was validated and 66.1% of silver recovery was obtained.

Conclusion: Response surface methodology was successively used to optimize thiourea leaching recovery of silver from PCBs of the waste computers. The result obtained could be scaled up to pilot plant.

Open Access Original Research Article

Vortex Assisted Dispersive Liquid-Liquid Microextraction: Determination of Cobalt by HPLC

F. Sánchez-Rojas, C. Bosch-Ojeda

Chemical Science International Journal, Page 1-8
DOI: 10.9734/CSJI/2017/32190

A simple an effective method was developed for preconcentration of cobalt in water samples. In the proposed approach, sodium diethyl dithiocarbamate (DDTC) was used as chelating agent, and vortex-assisted dispersive liquid-liquid microextraction combined with high performance liquid chromatography (HPLC) with UV detection was developed. In this method a small amount of chloroform as extracting solvent is rapidly injected by syringe into the water sample containing cobalt ions complexed by DDTC. This complex is extracted into the fine chloroform droplets and vortex agitation takes place during five minutes. The influence of variables affecting to the microextraction process were studied. Under the selected conditions, the preconcentration factor of 148 was achieved and the relative standard deviations (RSD) were 1.86% and 2.68% for 50 and 20 µg L-1 of cobalt, respectively. The proposed method was applied to analysis of water standard reference materials and the recovery range from 90.0 to 110.0%.

Open Access Original Research Article

Comparative Alpha-amylase Inhibitory Properties of the Leaf Extracts of Petiveria alliacea L.

Seide M. Akoro, Mutiat A. Omotayo, Sola Ajibaye, Funmi Dada

Chemical Science International Journal, Page 1-9
DOI: 10.9734/CSJI/2017/32528

Aims: The study was designed to determine the phytochemical contents and the inhibitory effects of the leaf extracts of Petiveria alliacea L. on alpha-amylase enzyme.

Study Design: Phytochemical Screening and in-vitro evaluation of alpha-amylase inhibitory effects of the leaf extracts of Petiveria alliacea L using starch-iodide and 3,5- dinitrosalicyclic acid assays.

Place and Duration: This work was carried out in the Chemistry Laboratory of the Department of Science Laboratory Technology (Chemistry Unit), School of Pure and Applied Science, Lagos State Polytechnic, Ikorodu and the Biochemistry Laboratory of the Nigerian Institute of Medical Research, Yaba, Lagos, Nigeria, between April and August 2016.

Methodology: Petiveria alliacea leaves was successively extracted with n-hexane, ethyl acetate, and ethanol by maceration for 72 h to obtain the respective extracts. Phytochemical screening of the extracts for the presence of secondary metabolites: tannins, alkaloid, flavonoids, cardiac glycosides, reducing sugar, saponins, and anthraquinones was carried out using standard methods. The percentage of alkaloids and flavonoids was determined using Harborne and Boham and Kocipaiabyazan methods respectively. In-vitro alpha-amylase inhibitory properties of the leaf extracts were carried out by starch-iodine and 3,5-dinitrosalicyclic acid reagent (DNSA reagent) assays using acarbose as the standard.                                                                                    

Results: The results showed alkaloids, cardiac glycosides were detected in all the extracts. saponins, flavonoids, anthraquinones and reducing sugars were detected in the ethyl acetate and ethanol extracts; steroids are detected in the hexane extract only; tannins and terpenoids were not detected in all the extracts. The percentage of alkaloids and flavonoids are 2.14±0.16% and 6.14±1.07% respectively. All the extracts showed positive Alpha-amylase inhibitory properties with percentage inhibition increasing with increase in concentration. starch-iodine and 3,5- dinitrosalicyclic acid reagent assays gave similar values for percentage inhibition of alpha-amylase at 50 and 100 µg/mL concentration of extracts in the hexane, ethyl acetate extracts and acarbose with slightly different values for the ethanol extract. 

Conclusion: The results suggested Petiveria alliacea leaf extracts could reduce post-prandial glucose level in type 2 diabetes mellitus and both methods of assay are effective.

Open Access Original Research Article

Effect of Formulations on Functional Properties and Storage Stability of Nutritionally Enriched Multigrain Pasta

Harsimran Kaur, Hanuman Bobade, Arashdeep Singh, Baljit Singh, Savita Sharma

Chemical Science International Journal, Page 1-9
DOI: 10.9734/CSJI/2017/33348

High fiber low gluten whole grain flours of wheat, barley, soybean, maize, millets, mungbean, oats and flaxseeds were blended in various proportions as a partial replacement for wheat flour along with Xanthan gum @ 2% for the development of nutritionally enriched pasta. Prepared pasta samples were assessed for cooking quality, color characteristics, sensory properties and selected samples were packed in HDPE bags and stored for 90 days and the stored samples were analyzed for changes in their moisture content, free fatty acids, water activity, cooking quality and overall acceptability at 30 days interval. Substitution of wheat flour by multigrain flour in pasta making significantly (p<0.05) increased the water absorption and volume expansion while it significantly (p<0.05) decreased the cooking time. The loss of solids in cooking water increased significantly (p<0.05) with the use of multigrain flour. Color characteristics and overall acceptability scores of multigrain pasta were comparable with pasta made of wheat flour. Cooking quality of pasta was not significantly influenced by the 90 days storage period. Significant (p<0.05) increase in moisture content, water activity and free fatty acid was found during the 90 days storage. However, the changes in quality parameters during storage were well within the limit and in acceptable range.

Open Access Original Research Article

Phenolic Foam Reinforced by Cedar’s Resin

Ramzy Hamed, Yolla Kazzi, Houssein Awada

Chemical Science International Journal, Page 1-6
DOI: 10.9734/CSJI/2017/33377

Recently phenolic foams have been received much attention because of their excellent properties including flame resistance, low density, high thermal stability over a broad temperature range and low generation of toxic gases during combustion. Cedar resin was used as a toughening agent to modify the brittleness of phenolic foam. The cedar resin was first introduced to the phenol formaldehyde resin. The mixture was successfully used to prepare phenolic foam using appropriate combinations of flowing agent. Benzene Sulfonic acid was employed as a curing agent. Orthophosphoric acid and nonionic surfactant polyoxyethylene were used as foaming agent and surfactant respectively.

The mechanical properties results showed that the incorporation of cedar resin into phenolic foam dramatically improved the compressive strength indicating the excellent toughening effect of cedar resin. In addition this property is depended to the percentage of the cedar resin. The apparent density data indicated that the addition of cedar resin can increase the apparent density of phenolic foam.