Hanafy Holail

Remediation of lead by pretreated red algae: adsorption isotherm, kinetic, column modeling and simulation studies

Batch and column biosorption experiments were carried on for lead uptake using ecofriendly biosorbents (raw and calcium chloride [CaCl2] or formaldehyde pretreated form of red marine algae Jania ruben [Linnaeus]). The best-fit (linear and nonlinear) isotherms, kinetics, and column adsorption models were identified using statistical analysis. Freundlich, Langmuir, Temkin, Redlich–Peterson, and Elovich adsorption isotherm models were tested. Highest adsorption capacity (774 mg/g) has been observed with Jania algae pretreated with formaldehyde. Pseudo-first- and second-order adsorption kinetics were applicable. The column capacity for lead removal with Jania pretreated with CaCl2 was found to be 1089.6 (mg/g) from the breakthrough curve area method. Thomas, Yoon-Nelson, Yan, and Clark column models were tested with regression analysis. Thomas model is the best column model with capacity qTh = 1092.4 mg/g. Overall, 98.5% regeneration of column was achieved, indicating the suitability of using algae materials in multioperational cycles. Adsorbed lead present in algae material was confirmed by thermal analysis.

Improving Water Use Efficiency in Semi-Arid Regions through Integrated Aquaculture/Agriculture

Two experiments were performed in the Bekaa plain in Lebanon to evaluate the feasibility of integrating aquaculture with established agriculture production in order to increase water productivity. Both experiments consisted of four plant management treatments: 1) Aquaculture effluent irrigation and no fertilizer; 2) aquaculture effluent irrigation and inorganic fertilizer; 3) well water irrigation and no fertilization; and 4) well water irrigation with inorganic fertilizer. In the first experiment, tilapia growth and radish production using aquaculture effluent were evaluated. All fish survived and grew, and radish production was improved by irrigating with aquaculture effluent. In the second experiment, maize (Zea mays) in large plots was irrigated with aquaculture effluent. Irrigation with effluent water improved maize production and improved soil nitrogen availability. In both experiments, fish production improved water value index and water use efficiency. Results suggest that aquaculture effluent can supplant inorganic fertilizers and could actually yield better crop production.

Antimicrobial and biocide resistance of bacteria in a Lebanese tertiary care hospital

The environment in a Lebanese tertiary-level care hospital was examined for bacterial contamination. In total, 8 open-air and 62 surface samples were taken and CFU were enumerated. Morphologically different isolates (n=104) were obtained and tested for resistance to a wide range of antibiotics by the Kirby-Bauer disc diffusion method. Minimum bactericidal concentrations of isolates to seven different biocides used within this facility were also determined using both qualitative and quantitative methods. Gram-positive bacteria (82.7% of isolates) were encountered more often than Gram-negative bacteria (17.3%), and the genus Staphylococcus was most prevalent among isolates (59.6% of the isolates). Gram-positive isolates showed the highest resistance to penicillin (60.6%), clindamycin (54.5%) and ceftazidime (39.4%); the lowest frequencies of resistance were seen with vancomycin (0% of isolates), nitrofurantoin (3.5%), tetracycline (12.1%) and ciprofloxacin (12.1%). The prevalence of meticillin-resistant Staphylococcus aureus (MRSA) and meticillin-resistant coagulase negative staphylococci among all environmental samples was 3.8% and 11.5% of isolates, respectively. All Gram-negative isolates were multidrug-resistant (MDR). With respect to biocides, the highest frequency of resistance was to quaternary ammonium compounds (QACs) (13.5% of isolates) and the lowest frequency of resistance was to QAC/biguanide complex (<1% of isolates) and Anios DVA (3.8%). MDR bacteria can pose a serious threat in the hospital environment, showing the need for prudent use of antibiotics and correct infection control procedures.

Adsorptive kinetic mechanism of heavy metal cations on the surface of graphite oxide and its SiO2 composite

Nanomaterials have gained great attention because of their novel size- and shape-dependent properties, large specific surface area and high reaction activity. Moreover, nanomaterials have a wide range of applications, as in the technological and environmental challenges in the areas of solar energy conversion, catalysis, medicine, and water treatments. In the present study, nanostructured graphite oxide, silica/graphite oxide composites and silica nanoparticles were used for the removal of the heavy metal ions from aqueous solutions by a batch adsorption method and the adsorptive kinetic mechanism of heavy metal cations on the surface of graphite oxide and its SiO2 composite was evaluated. The experimental results revealed a strong adsorption of the metal cations on the surface of graphite oxide, this is reflected in the shifts in wave numbers after adsorption with nanostructured graphite oxide and the big shift in wave numbers (Δv) for nickel ions reflects chemosorption type of adsorption. This is confi...