Lignocellulolytic enzymes play a crucial role in efficiently converting lignocellulose into valuable platform molecules in various industries. However, they are limited by their production yields, costs, and stability. Consequently, their production by producers adapted to local environments and the choice of low-cost raw materials can address these limitations. Due to the large amounts of olive stones (OS) generated in Morocco which are still undervalued, Penicillium crustosum, Fusarium nygamai, Trichoderma capillare, and Aspergillus calidoustus, are cultivated under different fermentation techniques using this by-product as a local lignocellulosic substrate. Based on a multilevel factorial design, their potential to produce lignocellulolytic enzymes during 15 days of dark incubation was evaluated. The results revealed that P. crustosum expressed a maximum total cellulase activity of 10.9 IU/ml under sequential fermentation (SF) and 3.6 IU/ml of β-glucosidase activity under submerged fermentation (SmF). F. nygamai recorded the best laccase activity of 9 IU/ml under solid-state fermentation (SSF). Unlike T. capillare, SF was the inducive culture for the former activity with 7.6 IU/ml. A. calidoustus produced, respectively, 1,009 μg/ml of proteins and 11.5 IU/ml of endoglucanase activity as the best results achieved. Optimum cellulase production took place after the 5th day under SF, while ligninases occurred between the 9th and the 11th days under SSF. This study reports for the first time the lignocellulolytic activities of F. nygamai and A. calidoustus. Furthermore, it underlines the potential of the four fungi as biomass decomposers for environmentally-friendly applications, emphasizing the efficiency of OS as an inducing substrate for enzyme production.

Olive trees constitute one of the largest agroindustries in the Mediterranean area, and their cultivation generates a diverse pool of biomass by-products such as olive tree pruning (OTP), olive leaves (OL), olive stone (OS), and extracted olive pomace (EOP). These lignocellulosic materials have varying compositions and potential utilization strategies within a biorefinery context. The aim of this work was to carry out an integral analysis of the aqueous extractives fraction of these biomasses. Several analytical methods were applied in order to fully characterize this fraction to varying extents: a mass closure of >80% was reached for EOP, >76% for OTP, >65% for OS, and >52% for OL. Among the compounds detected, xylooligosaccharides, mannitol, 3,4-dihydroxyphenylglycol, and hydroxytyrosol were noted as potential enhancers of the valorization of said by-products. The extraction of these compounds is expected to be more favorable for OTP, OL, and EOP, given their high extractives content, and is compatible with other utilization strategies such as the bioconversion of the lignocellulosic fraction into biofuels and bioproducts.

BACKGROUND: The use of agricultural waste as a low-cost adsorbent for the removal of hazardous methylene blue (MB) from aqueous solution was investigated. In this research, the potentiality of using black nano olive stones (black NOS) and green nano olive stones (green NOS) for MB adsorption was conducted.
METHODS: Various remediation parameters such as initial MB concentration, pH, and temperature were investigated. Thermodynamic study was carried out to determine the homogeneity of the adsorbent and spontaneity of the adsorption process. Different physical and chemical characterizations were studied using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET) surface area, pore radius and pore volume.
RESULTS: It was found that NOS exhibits an acidic nature, however the highest MB removal efficiency was recorded at pH 10; reaching up to 71%. The negative value of the heat of the adsorption process (∆H ° ) indicated the reaction followed an exothermic pathway while the negative value of Gibbs adsorption (∆G ° ) further suggested its spontaneous nature. The results indicated that the Freundlich model described well the adsorption process with 99.5% correlation coefficient for green NOS. FTIR was used to analyze functional groups on the adsorbents\' surfaces that could play vital roles in the remediation process. SEM analysis revealed that the adsorbents comprised of abundant spherical deep cavities and porous nature.
CONCLUSIONS: The result obtained successfully demonstrated the potential of using black and green NOS as suitable adsorbents for the removal of MB from water.

Spent olive pomace from the two-phase extraction system of virgin olive oil and olive pomace oil, is a major agro-industrial residue. Present study aimed at the valorization of residual olive pomace and stones (seeds) by hydrothermal treatment and enzymatic hydrolysis of glucans. Both residues contain lignin (31.2% and 42.1%), glucans (13.8% and 15.3%) and xylans (18.9% and 20.3%). After hydrothermal pretreatment (130 °C, 30 min; severity factor log R0 = 2.99), 65% and 75% of hemicelluloses (65% of xylan) were hydrolysed into xylo-oligosaccharides in pomace and stones, respectively. Cellulose and lignin were not substantially affected. Three commercial enzyme preparations, Saczyme Yield, Ultimase BWL 40 and Celluclast 1.5 L, were evaluated for saccharification of pomace or stones at three biomass loads (10, 20 and 30%, w/v). Saczyme and Ultimase were active with high solid loads (30%), reaching 80 and 90% of glucan conversion in pomace, and 40 and 55% in stones, respectively, after 5 h.

The textural properties and surface chemistry of different activated carbons, prepared by the chemical activation of olive stones, have been investigated in order to gain insight on the NO₂ adsorption mechanism. The parent chemical activated carbon was prepared by the impregnation of olive stones in phosphoric acid followed by thermal carbonization. Then, the textural properties and surface chemistry were modified by chemical treatments including nitric acid, sodium hydroxide and/or a thermal treatment at 900 °C. The main properties of the parent and modified activated carbons were analyzed by N₂-adsorption, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques, in order to enlighten the modifications issued from the chemical and thermal treatments. The NO₂ adsorption capacities of the different activated carbons were measured in fixed bed experiments under 500 ppmv NO₂ concentrations at room temperature. Temperature programmed desorption (TPD) was applied after adsorption tests in order to quantify the amount of the physisorbed and chemisorbed NO₂. The obtained results showed that the development of microporosity, the presence of oxygen-free sites, and the presence of basic surface groups are key factors for the efficient adsorption of NO₂.

The main purpose of this study was to understand the effect of time and temperature during the hydrothermal carbonisation (HTC) of olive stones (OS). For that purpose, the severity factor was introduced, by which the effect of the HTC conditions on the resultant products could be described. HTC was carried out at various temperatures (160, 180, 200, 220 and 240 °C) and times (3, 6, 12, 24 and 48 h) for producing 25 hydrochars. The yield to hydrochar varied from 70 to 50%. Hydrochars were all submitted to thermogravimetric and elemental analysis. The liquid fractions were also recovered and analysed in order to valorise OS as completely as possible. Thus, highly added-value products such as furfural and 5-hydroxymethylfurfural were detected. At the highest temperature and time, the hydrochar elemental composition was similar to that of lignite coals. Hydrochars were further carbonised at 900 °C, leading to materials with surface areas as high as 1200 m2 g-1 and with narrow pore size distributions centred on 0.5 nm. The severity factor allowed finding clear tendencies in the production of hydrochars and derived carbons in terms of yield, composition, and surface area, which would have been hardly analysed if the effects of temperature and time had to be considered separately. We proved that the severity factor, which use is quite uncommon in studies dealing with materials production, is a valuable tool for studying the effects of HTC experimental conditions.

A chemical-activated carbon (CAC) was prepared by phosphoric acid activation of olive stone. The CAC was characterized using various analytical techniques and evaluated for the removal of amoxicillin from aqueous solutions under different operating conditions (initial concentration, 12.5-100 mg L-1, temperature, 20-25 °C, contact time, 0-7000 min). The CAC characterization indicates that it is a microporous carbon with a specific surface area of 1174 m2/g and a pore volume of 0.46 cm3/g and contains essentially acidic functional groups. The adsorption tests indicated that 93 % of amoxicillin was removed at 20 °C for 25 mg L-1 initial concentration. Moreover, it was found that adsorption capacity increased with contact time and temperature. Kinetic study shows that the highest correlation was obtained for the pseudo-second-order kinetic model, which confirms that the process of adsorption of amoxicillin is mainly chemisorption. Using the intraparticle diffusion model, the mechanism of the adsorption process was determined. The equilibrium data analysis showed that the Sips and Langmuir models fitted well the experimental data with maximal adsorption capacities of 67.7 and 57 mg/g, respectively, at 25 °C. The chemical-activated carbon of olive stones could be considered as an efficient adsorbent for amoxicillin removal from aqueous solutions.