A Review on Utilization Routes of the Leather Industry Biomass

The use of biomass to produce bioenergy and biomaterials is considered a sustainable alternative to depleting fossil fuel resources. The world tanneries consume 8–9 MT of skin and hide every year producing 1.4 MT of solid waste. Most of the solid biomass generated from tanneries is disposed of as waste in the environment using either landfilling or thermal incineration. Disposal of this waste into the environment affects the ecosystem, causing bad odor (air pollution) and has an antagonistic impact on the environment. Due to this, European Union legislation bans the landfilling of biomass. This study aims to comprehensively review the possible valorization routes of leather processing industry biomass into high-value biomaterials. Leather biomass (trimmings, shaving, splitting, and buffing dust) mainly contain 30%–35% collagen protein, which is produced by acid or alkali hydrolysis. The biopolymers obtained from leather industry biomass can be utilized in the production of several high-value materials. In addition, leather processing industry biomass also contains fat, which can be converted into a bio-surfactant, and other useful biomaterials. Keratin protein can also be extracted from the hair waste of hides and skins. The increased demand for biomaterials makes the using of leather industry biomass very attractive. From this study, it can be concluded that the conversions of leather processing industry waste to valuable biomaterial can protect the environment, generate additional income for leather industries, and pave way for sustainable and renewable biomaterials production.

Synthesis of Silica-Based Materials Using Bio-Residues through the Sol-Gel Technique

This study focused on the use of citrus bio-waste and obtention of silica-based materials through the sol-gel technique for promoting a greener and more sustainable catalysis. The sol-gel method is a versatile synthesis route characterized by the low temperatures the materials are synthesized in, which allows the incorporation of organic components. This method is carried out by acid or alkali hydrolysis combined with bio-waste, such as orange and lemon peels, generated as co-products in the food processing industry. The main objective was to obtain silica-based materials from the precursor TEOS with different catalysts—acetic, citric and hydro-chloric acids and ammonium hydroxide—adding different percentages of lemon and orange peels in order to find the influence of bio-waste on acids/alkali precursor hydrolysis. This was to partially replace these catalysts for orange or lemon peels. The solids obtained were characterized with different techniques, such as SEM, FT₋IR, potentiometric titration and XRD. SEM images were compared with pure silica obtained to contrast the morphology of the acidic and alkali hydrolysis. However, until now, few attempts have been made to highlight the renewability of reagents used in the synthesis or to incorporate bio-based catalytic processes on larger scales.

Industrial Gelatin from Leather Chrome Shavings Wastes

A step towards minimizing the environmental pollution of leather tanning , leather chrome shavings wastes were treated with Li2CO3 to extract technical or industrial gelatin as an added value material. Isolation and characterization of gelatin obtained from chrome-tanned shavings were done. The alkali hydrolysis products obtained, showed good physical and chemical properties in terms of gel strength, swelling and thermal stability. The optimum hydrolysis conditions using Li2CO3 were found to be 5 hr. extraction at 80°C, swelling time of one day and pH 9.5. The yield was over one third of the original starting waste material.

Starch Nanoparticles Preparation and Characterization by in situ combination of Sono-precipitation and Alkali hydrolysis under Ambient Temperature

The current work aimed at adopting in situ combination of sono-precipitation and alkali hydrolysis as a rapid technique for starch nanoparticles (SNPs) preparation under ambient conditions with a high yield. Factors affecting the preparation of SNPs were investigated based on statistical analysis using the Box Behnken design. The particle size and polydispersity index of particles were used as dependent variables to obtain the optimized formulation. The SNPs optimized formulation (F14) was further characterized for zeta potential, transmission electron microscopy, Fourier transform infrared spectroscopy, differential thermal analysis and X-ray diffraction. The results of particle size were between 44.82±3.31 and 83.93±8.53 while polydispersity index results were ranged from 0.106±0.012 to 0.179±0.018. The results obtained revealed the efficiency of the technique in obtaining a high yield (98.72% ±0.89) of well-distributed nanoparticles. Also, the SNPs obtained were spherical in shape with good stability, as indicated by zeta analysis (-20±0.25mV) and thermal analysis. The data obtained also showed no change in the chemical structure of the SNPs, as indicated by the infrared transmission of Fourier, thermal analysis, and the relative crystallinity of SNPs was decreased compared with native maize starch indicating the crystallite is transformed from crystalline to amorphous form. The obtained results concluded the efficiency of the adopted method on obtaining SNPs in a short preparation time with a high yield under ambient conditions.

DEVELOPMENT OF A VALIDATED STABILITY-INDICATING METHOD FOR ESTIMATION OF ETHIONAMIDE IN TABLETS BY RP-HPLC AND CHARACTERIZATION OF ITS ISOLATED ALKALI DEGRADATION PRODUCT

A simple, accurate, reproducible and specific stability-indicating RP-HPLC method was developed for estimation of ethionamide in tablets. Ethionamide was exposed to acid, alkali and neutral hydrolysis at elevated temperatures, to thermolytic degradation, peroxide-mediated oxidation at room temperature in dark and to photolytic degradation. The drug was found stable to thermolytic and photolytic conditions and to neutral hydrolysis. However, substantial degradation was obtained in acid and alkali hydrolysis and complete degradation in peroxide-medicated oxidation. Similar degradation behavior was observed when ethionamide tablets were exposed to the mentioned forced degradation conditions. The method showed adequate resolution of drug from its potential degradation products on C18 (250 × 4.6 mm, 5µ) column using mobile phase of methanol: water (50: 50 % V/V) at 1 mL/min. The drug and its potential degradation products were detected at 290 nm. The method was validated as per the ICH Q2(R1) guidelines. The enrichment of the alkali degradation product was performed and isolated by preparative TLC and further confirmed by NMR and IR spectroscopy.

Extraction and Processing of Pharmaceutical Grade Microcrystalline Cellulose from Dracaena arborea Stem

Cellulose is an abundant renewable biodegradable polymer regarded as a promising feedstock for chemical productions with its versatility evaluated as a useful structural and functional material for pharmaceutical and industrial applications. It is a straight chain polymer which appears in cell walls of most plant and consists of D. glucose units, with absence of coiling or branching and can be derived from variety of sources including: annual plants, microbes, animals etc. Three basic types of cellulose often exist in nature as - alpha (α), beta (β) and gamma (ϒ). Microcrystalline cellulose (MCC) sourced from cellulose, occurs as a purified and partially depolymerized alpha cellulose from plant parts such as D. arborea stem possibly by severe acid or alkaline hydrolysis. D. arborea plant is a palm – like tree of 1.5m height with several branches, often used as a boundary mark, a non-selective habitat and belongs to the family Asparagaceae, sub family Nolinoideae. With alkali hydrolysis of the D. arborea stem, the percentage yield of MCC from the alpha cellulose is 54.32%. Physicochemical analysis of the MCC reveals it to have a pH of 7.80 and physicotechnical analysis resulted in values as recommended in the official monogragh. Proximate principles of the extracted MCC, depicted percentage fiber content as 65.78% and low lipid and protein content as 0.6 and 0.4% respectively. Elemental analysis shows the composition of sodium and iron as 41% and 35% respectively but absence of lead and other deleterious materials. FTIR analysis suggests the presence of carbonyl groups, 6- membered cyclic ring (aromatic structure) with ortho and meta - OH substitution and long aliphatic chains. The x-ray diffraction study gave a percentage crystalinity index of 6.02 at 2q = 22 and 2q = 34.