Nassereldeen Ahmed Kabbashi

Kinetic adsorption of application of carbon nanotubes for Pb(II) removal from aqueous solution

The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(II) reached maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coefficients from Langmuir isotherm model indicates the strong adsorptions of Pb(II) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). The results indicates that the highest percentage removal of Pb (96.03%) can be achieved at pH 5, 40 mg/L of CNTs, contact time 80 min, and agitation speed 50 r/min.

Sludge palm oil as a renewable raw material for biodiesel production by two-step processes

In this study, biodiesel was produced from sludge palm oil (SPO) using tolune-4-sulfonic monohydrate acid (PTSA) as an acid catalyst in different dosages in the presence of methanol to convert free fatty acid (FFA) to fatty acid methyl ester (FAME), followed by a transesterification process using an alkaline catalyst. In the first step, acid catalyzed esterification reduced the high FFA content of SPO to less than 2% with the different dosages of PTSA. The optimum conditions for pretreatment process by esterification were 0.75% (w/w) dosage of PTSA to SPO, 10:1 M ratio, 60 °C temperature, 60 min reaction time and 400 rpm stirrer speed. The highest yield of biodiesel after transesterification and purification processes was 76.62% with 0.07% FFA and 96% ester content. The biodiesel produced was favorable as compared to EN 14214 and ASTM 6751 standard. This study shows a potential exploitation of SPO as a new feedstock for the production of biodiesel.

Effect of Process Parameters on Yield and Conversion of Jatropha Biodiesel in a Batch Reactor

In a quest for environmental friendly energy source with least pollutants emission due to issues of global warming coupled with dwindling reserve of the fossil fuel, researchers have intensified study on renewable fuels. Among these renewable energy sources, biodiesel stands prominent. Biodiesel production is largely by transesterification of transglycerides of fatty acids almost always in a batch reactor. Of importance in the yield generation and fatty acid methyl esters conversion is the feedstock purity, control of reagents use in production and operation parameters alteration. This is geared towards achieving optimum resource conservation while also minimizing cost and materials wastage. In this study biodiesel was produced from hydrolysate (free fatty acids from hydrolyzed Jatropha curcas oil) using calcinated niobic acid catalyst at controlled rates of process parameters. Yield and conversion up to 97.7% and 100% respectively of the alkyl esters produced. This informs the influence of process parameters significantly on the throughput of the final product.

Sewage sludge composting simulation as carbon/nitrogen concentration change

Available composting models do not describe accurately the dynamics of composting processes. Difficulty in modeling composting processes is attributed mainly to the unpredicted change in process rate caused by change in activation energy value (E). This article presented the results of an attempt made to utilize patterns of change in carbon, nitrogen and temperature profiles to model sewage sludge composting process as a multi-stage process. Results of controlled sewage sludge composting experiments were used in the study. All the experiments were carried out as batch experiments in a 300-liter Horizontal Drum Bioreactor (HDB). Analysis of the profiles of carbon, nitrogen and temperature has indicated that there were clear patterns that could be used to develop simple models of the process, the initial C/N ratio was between 7-8 and the final C/N ratio of the compost in most experiments were found to be around 15.0, indicating the compost was fully matured and could be used safely for agricultural purpose. Electrical conductivity of composting material decreased from 1.83 to 1.67 dS/m, after a period, it increased gradually from 2.01 to 2.23 dS/m and remained at around 2.33 dS/m till the end of composting. It is found that change in the concentration of total carbon can reasonably be described by three constant process rate coefficients (k1, k2, k3). It is found that the process starts with a certain process rate coefficient (k1) and continues until peak temperature is reached, then it reaches lower process (k2) in the declining phase of the thermophilic stage, and finally it proceeds with a faster process rate (k3) when maturation is reached. Change in the concentration of total nitrogen has shown to have the same patterns of change as carbon.

Solid Waste Management in Africa: A Review

As a result of globalization, the quantity and generation rate of solid waste in Africa have increased tremendously and this calls for the need to salvage the situation before it gets out of hand. This article presents the review of solid waste trends in Africa from the pre-colonial era till the present day. It also discusses the composition of solid wastes, collection, transportation and disposal in different African countries. Different types of waste have been generated over the years but the management strategies implemented are inadequate. Waste management in African is faced with numerous challenges and recommendations for improved and efficient solid waste management have been proposed.

Statistical Optimization of Process Conditions for Direct Bioconversion of Sewage Treatment Plant Sludge for Bioethanol Production

The production of bioethanol was conducted by utilizing domestic wastewater sludge as major substrate with the aid of yeast, Saccharomyces cerevisiae using liquid state bioconversion method (submerged fermentation). The optimization of process conditions such as temperature, initial pH, inoculum dosage and agitation was carried out by using the central composite design (CCD) formulated by a statistical optimization software MINITAB. Optimization of process conditions was done with different ranges of temperature, pH, inoculum sizes and agitations with fixed media compositions obtained from previous study. A polynomial regression model was developed to determine the optimum compositions. Several techniques such ANOVA, t-test, p-values were observed to evaluate the model as well as the optimization process. The maximum ethanol production (9.1% v/v) was found while model equation predicted ethanol production with 11.9% v/v using the optimum conditions: temperature of 33°C, pH of 7, agitation of 200 rpm and inoculum of 1%. The results indicated that the temperature was highly significant (p<0.01) followed by the pH (p<0.01), inoculum (p<0.05) and agitation rate (p<0.05). The coefficient of determination (R2) was 90.1% which satisfied the adjustment of experimental data in the model.

Liquid State Bioconversion of Domestic Wastewater Sludge for Bioethanol Production

The production of bioethanol was conducted by utilizing domestic wastewater sludge as major substrate using the yeast, Saccharomyces cerevisiae in liquid state bioconversion method (submerged fermentation). The optimum media and process conditions obtained from previous studies by using central composite design were applied in this study to evaluate the bioconversion process through ethanol production. The results presented in this study showed that 9.8% ethanol was produced utilizing sludge as substrate by Saccharomyces cerevisiae within 48 hours of fermentation while the COD, copper and chromium (heavy metals) removal were found to be 62%, 68% and 45% respectively in treated sludge after 72 hours of fermentation period. The total suspended solids (TSS) as biosolids (microbial growth) was observed to evaluate the microbial performance in bioconversion process. The observed yield and productivity were determined as well.

Integrated Scheduled Waste Management System in Kuala Lumpur using Expert System

Over the past decade, Malaysia has enjoyed tremendous growth in its economy. This has brought about a population growth together with a great influx of foreign workforce to the cities. This resulted in an increase in the amount of scheduled waste generated. Furthermore, scheduled waste management has long been a problem for local authorities in Kuala Lumpur. Continued illegal dumping by waste generators is being practiced at large scale due to lack of proper guidance and awareness. This report reviewed and discussed service provided for scheduled waste management by an authority and international scenario of scheduled waste management. An expert system was developed to integrate scheduled waste management in Kuala Lumpur. The knowledge base was acquired through journals, books, magazines, annual report and web sites. An object oriented expert system shell, Microsoft Visual Basic 2005 Express Edition was used as the building tool for the prototype development. The overall development of this project was carried out in several phases which are problem identification, problem statement, literature review, identification of domain experts, prototype development, knowledge acquisition, knowledge representation and prototype development. Scheduled waste expert system is developed based on five types of scheduled waste management which are label requirements, packaging requirements, impact of scheduled wastes, recycling of scheduled wastes and recommendations. Besides, it contains several sub-modules by which the user can obtain a comprehensive background of the domain. The output is to support effective integrated scheduled waste management.

Application of activated carbon from empty fruit bunch (EFB) for mercury [Hg(II)] removal from aqueous solution

Mercury is a heavy metal and is used widely in the industry, making it a global problem. It accounts for approximately 70% of man-made emissions. Activated carbon was found to be efficient for the adsorption of Hg(ll) in aqueous solution. The characterization of Hg(ll) uptake showed that the mercury binding is dependent on initial pH, agitation speed, amount of dosage and also the interaction between pH and contact time. From the experiment, the initial concentration of mercury was set to be 1.6 mg/L. It was found that the minimum residual concentration of mercury was 0.0075 mg/L (99.53%) at the condition of pH 6.5, agitation speed of 100 rpm, contact time of 70 min and AC dosage of 20 mg. This value was considered acceptable as it met the requirement of the Department of Environment, Malaysia.

Metabolic profiling of flavonoids, saponins, alkaloids, and terpenoids in the extract from Vernonia cinerea leaf using LC-Q-TOF-MS

Abstract The leaves of Vernonia cinerea are widely used for medicinal purposes. Although, different studies have reported on the biological activities of the plant extracts whereas the tentative assignment of secondary metabolites that include flavonoids, saponins, alkaloids, and terpenoids had not been reported. Thus, this study tentatively assigned the flavonoids, saponins, alkaloids, and terpenoids in the extract of V. cinerea leaves that are mainly responsible for the reported activities. Liquid chromatography-mass spectrometry quadrupole time of flight (LC-Q-TOF-MS) analysis was employed in the assignments. The results obtained showed that a total number of 221 compounds were tentatively assigned in the extract of V. cinerea leaves which include 64 flavonoids, 13 saponins, 36 alkaloids, and 108 terpenoids. These phytochemicals can further be isolated, purified, characterized, and quantified due to their importance. Graphical Abstract