Behzad Ahvazi

Preparation of lignopolyols from wheat straw soda lignin.

Wheat straw soda lignin was modified and characterized by several qualitative and quantitative methods such as (31)P NMR spectroscopy to evaluate its potential as a substitute for polyols in view of polyurethane applications. Chemical modification of the lignin was achieved with propylene oxide to form lignopolyol derivatives. This was performed by a two-step reaction of lignin with maleic anhydride followed by propylene oxide and by direct oxyalkylation under acidic and alkaline conditions. The physical and chemical properties of lignopolyols from each method and the subsequent chain-extended hydroxyl groups were evaluated. Direct oxyalkylation of lignin under alkaline conditions was found to be more efficient than acidic conditions and more effective than the two-step process for preparing lignopolyol with higher aliphatic hydroxyl contents.

Sorption of 2,4-dinitroanisole （DNAN） on lignin

The present study describes the use of two commercially available lignins, namely, alkali and organosolv lignin, for the removal of 2,4-dinitroanisole (DNAN), a chemical widely used by the military and the dye industry, from water. Sorption of DNAN on both lignins reached equilibrium within 10 hr and followed pseudo second-order kinetics with sorption being faster with alkali than with organosolv lignin, i.e. k2 10.3 and 0.3 g/(mg x hr), respectively. In a separate study we investigated sorption of DNAN between 10 and 40 degrees C and found that the removal of DNAN by organosolv lignin increased from 0.8 to 7.5 mg/g but reduced slightly from 8.5 to 7.6 mg/g in the case of alkali lignin. Sorption isotherms for either alkali or organosolv lignin best fitted Freundlich equation with enthalpy of formation, deltaH0 equaled to 14 or 80 kJ/mol. To help understand DNAN sorption mechanisms we characterized the two lignins by elemental analysis, BET nitrogen adsorption-desorption and 31P NMR. Variations in elemental compositions between the two lignins indicated that alkali lignin should have more sites (O- and S-containing functionalities) for H-bonding. The BET surface area and calculated total pore volume of alkali lignin were almost 10 times greater than that of organosolv lignin suggesting that alkali lignin should provide more sites for sorption. 31P NMR showed that organosolv lignin contains more phenolic -OH groups than alkali lignin, i.e., 70% and 45%, respectively. The variations in the type of OH groups between the two lignins might have affected the strength of H-bonding between DNAN and the type of lignin used.

Proton spin-lattice relaxation time measurements of solid wood and its constituents as a function of pH: part II.

By measuring the proton spin–lattice relaxation times (T1H) in the solid-state for black spruce softwood, the molecular mobilities of carbohydrates and lignin have been evaluated as a function of pH. These studies have shown that the mobility of the polymeric constituents of wood is affected by the ionization of the different functional groups at different pHs. The analyses of the proton-spin–lattice relaxation time data at constant humidity revealed that the maximum T1H for both carbohydrates and lignin occurs at about neutrality, while it was found to be depressed at the two extremes of the pH range. By treating a wood sample with propylene oxide, the esterification of the acid groups was affected, thus deactivating the ionization process and their contribution to T1H. The experimental T1H values for cellulose and lignin after the esterification were significantly decreased at pH 6 confirming that their ionization plays a very significant role in determining chain mobility.

Proton spin–lattice relaxation time measurements of solid wood and its constituents as a function of pH: Part I*

Summary By measuring the proton spin–lattice relaxation times (T1H) in the solid-state for black spruce softwood, the molecular mobilities of carbohydrates and lignin have been evaluated as a function of pH. These studies have shown that the mobility of the polymeric constituents of wood is affected by the ionization of the different functional groups at different pHs. The analyses of the proton-spin–lattice relaxation time data at constant humidity revealed that the maximum T1H for both carbohydrates and lignin occurs at about neutrality, while it was found to be depressed at the two extremes of the pH range. By treating a wood sample with propylene oxide, the esterification of the acid groups was affected, thus deactivating the ionization process and their contribution to T1H. The experimental T1H values for cellulose and lignin after the esterification were significantly decreased at pH 6 confirming that their ionization plays a very significant role in determining chain mobility.

Performance of green corrosion inhibitors from biomass in acidic media

Abstract There has been a strong interest worldwide in developing suitable technologies that can derive chemicals and materials from renewable biomass in a number of applications, including corrosion inhibitors. In spite of the efficacy of conventional inhibitors in corrosion control, current corrosion inhibitors exhibit toxicity and/or are non-biodegradable. Therefore, industry efforts are leading to the development of non-toxic and environmentally friendly “green” corrosion inhibitors from renewable resources. Extensive studies of different bio-based inhibitors show that a vast number of phytochemicals can be used as efficient corrosion inhibitors. This paper provides a comprehensive review of the corrosion inhibition properties of plant-derived chemicals classified under the parameters provided by botanical chemistry.