Enhanced pretreatment, characterization and utilization of Prosopis juliflora stem for bioethanol production

Purpose –Prosopis juliflora is a raw material for long-term sustainable production of bioethanol. The purpose of this paper is to identify the best combination of pre-treatment strategy implemented on the lignocellulosic biomass Prosopis juliflora for bioethanol production. Design/methodology/approach – Pre-treatment of lignocellulosic material was carried out using acid, alkali and sonication in order to characterize the biomass for bioethanol production. Prosopis juliflora stem was subjected to steam at reduce temperature (121°C) for one hour residence time initially. Further acid and alkali treatment was carried out individually followed by combinations of acid and sonication, alkali and sonication. Sodium hydroxide, potassium hydroxide, hydrochloric acid, sulphuric acid and nitric acid were used with 3 per cent (w/v) and 3 per cent (v/v) concentration under temperature range of 60-90°C for 60 min incubation time. Sonication under 60°C for 5 min and 40 KHz frequency was carried out. Pre-treated sample were further characterised using field emission scanning electron microscope and Fourier transform infrared spectroscopy to understand the changes in surface morphology and functional characteristics. Findings – In sono assisted acid treatment-based method, nitric acid yields better cellulose content at 70°C and removes lignin that even at increased temperatures no burning was observed. Originality/value – The paper adds to the scarce research available on the combination of auto hydrolysis coupled with sono assisted acid/alkali hydrolysis which is yet to be practiced.

Acid and alkali treatment of kaolins

Two kaolins containing kaolinites of different crystallinity, as confirmed by the Aparicio-Galán-Ferrell index, were treated in HCl and KOH solutions at 95º and 80ºC, respectively, for periods up to 36 h. Changes resulting from the treatments have been characterized by several methods. Fe occurs in the octahedral sheets of both kaolinites and dissolves similarly to Al. Lower structural ordering, more structural defects and particles of smaller average size and less regular shape are responsible for faster dissolution of KGa-2 in comparison to well ordered Gold Field (Tanzania) kaolinite. More Si than Al is dissolved in KOH from both kaolins after any dissolution time. An aluminosilicate (feldspathoid) phase is thought to occur in the material prepared from KGa-2 in KOH. Near-IR spectra provide very useful information on changes in the mineral structure upon the treatments, on the solid reaction products and on the adsorbed water molecules.

Biomedical Thermodynamics and Implantology Aspects of Biocompatible Glass-Ceramics and Otherwise Modified Inorganic Materials and Surfaces

Some historical and recent attitudes aimed to bioactive inorganic materials are reviewed. The theory of bridging and non-bridging oxygen is reconsidered as well as the acid and alkali treatment of titanium surface necessary to achieve a good osteointegration. Some theoretical models to characterize mechanical properties are also reviewed.