Ahmad B. Albadarin

Influence of solution chemistry on Cr(VI) reduction and complexation onto date-pits/tea-waste biomaterials.

Tea waste (TW) and Date pits (DP) were investigated for their potential to remove toxic Cr(VI) ions from aqueous solution. Investigations showed that the majority of the bound Cr(VI) ions were reduced to Cr(III) after biosorption at acidic conditions. The electrons for the reduction of Cr(VI) may have been donated from the TW and DP biomasses. The experimental data obtained for Cr(VI)-TW and Cr(VI)-DP at different solution temperatures indicate a multilayer type biosorption, which explains why the Sips isotherm accurately represents the experimental data obtained in this study. The Sips maximum biosorption capacities of Cr(VI) onto TW and DP were 5.768 and 3.199 mmol/g at 333 K, respectively, which is comparatively superior to most other low-cost biomaterials. Fourier transform infrared spectroscopic analysis of the metal loaded biosorbents confirmed the participation of -COOH, -NH(2) and O-CH(3) groups in the reduction and complexation of chromium. Thermodynamic parameters demonstrated that the biosorption of Cr(VI) onto TW and DP biomass was endothermic, spontaneous and feasible at 303-333 K. The results evidently indicated that tea waste and date pits would be suitable biosorbents for Cr(VI) in wastewater under specific conditions.

Modelling and Fixed Bed Column Adsorption of Cr(VI) onto Orthophosphoric Acid-activated Lignin

Abstract The advantage of using an available and abundant residual biomass, such as lignin, as a raw material for activated carbons is that it provides additional economical interest to the technical studies. In the current investigation, a more complete understanding of adsorption of Cr(VI) from aqueous systems onto H3PO4-acid activated lignin has been achieved via microcolumns, which were operated under various process conditions. The practice of using microcolumn is appropriate for defining the adsorption parameters and for screening a large number of potential adsorbents. The effects of solution pH (2–8), initial metal ion concentration (0.483–1.981 mmol·L−1), flow rate (1.0–3.1 cm3·min−1), ionic strength (0.01–0.30 mmol·L−1) and adsorbent mass (0.11–0.465 g) on Cr(VI) adsorption were studied by assessing the microcolumn breakthrough curve. The microcolumn data were fitted by the Thomas model, the modified Dose model and the BDST model. As expected, the adsorption capacity increased with initial Cr(VI) concentration. High linear flow rates, pH values and ionic strength led to early breakthrough of Cr(VI). The model constants obtained in this study can be used for the design of pilot scale adsorption process.

Biosorption Characteristics of Sawdust for the Removal of Cd(ii) Ions: Mechanism and Thermodynamic Studies

Surface reaction methodology was employed for the optimization of cadmium removal onto sawdust with respect to various physico-chemical parameters. FT-IR was principally employed for the assessment of the chemical structure of sawdust. The biosorption equilibrium data were best represented by Khan and Langmuir isotherms. The monolayer sorption capacity obtained from Langmuir model was found to be 41.21 mg/g. Biosorption showed pseudo second order rate kinetics at different initial concentration of Cd(II). The intraparticle diffusion study indicated that film diffusion may be involved in the current study. Thermodynamic parameters showed that the sorption process is exothermic and non-spontaneous.

Dilute phosphoric acid-catalysed hydrolysis of municipal bio-waste wood shavings using autoclave parr reactor system.

The visibility of using municipal bio-waste, wood shavings, as a potential feedstock for ethanol production was investigated. Dilute acid hydrolysis of wood shavings with H₃PO₄ was undertaken in autoclave parr reactor. A combined severity factor (CSF) was used to integrate the effects of hydrolysis times, temperature and acid concentration into a single variable. Xylose concentration reached a maximum value of 17 g/100 g dry mass corresponding to a yield of 100% at the best identified conditions of 2.5 wt.% H₃PO₄, 175 °C and 10 min reaction time corresponding to a CSF of 1.9. However, for glucose, an average yield of 30% was obtained at 5 wt.% H₃PO₄, 200 °C and 10 min. Xylose production increased with increasing temperature and acid concentration, but its transformation to the degradation product furfural was also catalysed by those factors. The maximum furfural formed was 3 g/100 g dry mass, corresponding to the 24% yield.

The variability in nutrient composition of Anaerobic Digestate granules produced from high shear granulation.

This study investigates the production of organic fertilizer using Anaerobic Digestate (as a nutrient source) and limestone powder as the raw materials. A two-level factorial experimental design was used to determine the influence of process variables on the nutrient homogeneity within the granules. Increasing the liquid-to-solid ratio during granulation resulted in increased granule nutrient homogeneity. Increasing the processing time and the impeller speed were also found to increase the nutrient homogeneity. In terms of nutrients release into deionized water, the granules effectively released both potassium and phosphate into solution.

Effect of poly ethylene glycol on the mechanical and thermal properties of bioactive Poly (ε–caprolactone) melt extrudates for pharmaceutical applications

This paper investigates the effects of polyethylene glycol (PEG), on the mechanical and thermal properties of nalidixic acid/poly ε-caprolactone (NA)/PCL blends prepared by hot melt extrusion. The blends were characterized by tensile and flexural analysis, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. Results show that loading PEG in the PCL had a detrimental effect on the tensile strength and toughness of the blends, reducing them by 20-40%. The partial miscibility of the PCL-PEG system, causes an increase in Tg. While increases in the crystallinity is attributed to the plasticisation effect of PEG and the nucleation effect of NA. The average crystal size increased by 8% upon PEG addition. Experimental data indicated that the addition of NA caused loss of the tensile strength and toughness of PCL. Thermal analysis of the PCL showed that on addition of the thermally unstable NA, thermal degradation occurred early and was autocatalytic. However, the NA did benefit from the heat shielding provided by the PCL matrix resulting in more thermally stable NA particles.

Thermo-mechanical properties of poly ε-caprolactone/poly l-lactic acid blends: Addition of nalidixic acid and polyethylene glycol additives

The search for ideal biomaterials is still on-going for tissue regeneration. In this study, blends of poly ε-caprolactone (PCL) with poly l-lactic acid (PLLA), nalidixic acid (NA) and polyethylene glycol (PEG) were prepared. Mechanical and thermal properties of the blends were investigated by tensile and flexural analysis, DSC, TGA, WXRD, MFI, BET, SEM and hot stage optical microscopy. Results showed that the loading of PLLA caused a significant decrease in tensile strength and almost total eradication of the elongation at break of PCL matrix, especially after PEG and NA addition. Increased stiffness was also noted with additional NA, PEG and PLLA, resulting in an increase in the flexural modulus of the blends. Isothermal degradation indicated that bulk PCL, PLLA and the blends were thermally stable at 200°C for the duration of 2h making extrusion of the blends at this temperature viable. Morphological study showed that increasing the PLLA content and addition of the very low viscosity PEG and powder NA decreased the Melt Flow Indexer and increased the viscosity. At the higher temperature, the PLLA begins to soften and eventually melts allowing for increased flow and, coupling this with, the natural increase in MFI caused by temperature is enhanced further. The PEG and NA addition increased dramatically the pore volume which is important for cell growth and flow transport of nutrients and metabolic waste.

Nutrient Recovery from Waste Water: Optimisation of an Adsorption Process

Experimental design was used to study the effect of pH, initial solution concentration, contact time and dosage ratio of the adsorption of phosphorus from a synthetic waste water onto calcium carbonate based adsorbents. Interaction between the process variables was found to be important for the adsorption of phosphorus. The significance of these interaction effects have been highlighted by an Experimental Design approach undertaken. There was reasonable agreement between the Experimental Design model and independent experimental data, which indicates that the model equations are suitable for use in predicting the adsorption of phosphorus on calcium carbonate based adsorbents.

MitoQ Loaded Chitosan-Hyaluronan Composite Membranes for Wound Healing

Two self-associating biopolymers, namely chitosan (Ch) and a high-molar-mass hyaluronan (HA), were used to prepare membranes with the aim to protect and to enhance the healing of injured skin. A mitochondrially-targeted antioxidant—MitoQ—was incorporated into the mixture of biopolymers prior to their self-association. These three-component membranes were evaluated in detail utilising surface roughness measurements, contact angle measurements, hemocompatibility, and thrombogenicity analyses. Furthermore, in vivo application of Ch/HA/MitoQ membranes was assessed on injured rabbit and rat skin utilizing histological methods. The results showed that the prepared thrombogenic Ch/HA/MitoQ membranes had higher roughness, which allowed for greater surface area for tissue membrane interaction during the healing processes, and lower cytotoxicity levels than controls. MitoQ-loaded composite membranes displayed superior healing properties in these animal models compared to control membranes.

Preparation of Controlled Porosity Resorcinol Formaldehyde Xerogels for Adsorption Applications

The synthesis of resorcinol formaldehyde xerogels was investigated by controlling its porosity for potential use as adsorbents for heavy metals removal from industrial wastewater. Resorcinol formaldehyde carbon xerogels were synthesised by sol-gel polymerization of resorcinol (R) with formaldehyde (F) in the presence of sodium carbonate (C) and then vacuum dried. Resorcinol formaldehyde (RF) gels were synthesised at same temperature conditions with varying resorcinol / catalyst (R/C) and resorcinol / water (R/W) ratios. The influence of R/C and R/W ratios on the pore structure of the xerogels was investigated. Surface area and porosity of the resorcinol formaldehyde gels were analysed by physical adsorption (physiosorption) of nitrogen (N2) at 77 K. The result(s) showed an increase in mesoporosity and pore size as R/C ratio increases. At resorcinol / catalyst (R/C) of 200, the pore size and pore volume increased with increase in R/W ratio. From the result, it can be concluded that the resorcinol / catalyst (R/C) and resorcinol / water (R/W) ratios are two contributing factors to determining the pore structure of the xerogels.