The current fossil fuel reserves are not sufficient to meet the increasing demand and very soon will become exhausted. Pollution, global warming, and inflated oil prices have led the quest for renewable energy sources. Algal biofuels represent a potential source of renewable energy. Algae, as the third generation feedstock, are suitable for biodiesel and bioethanol production due to their quick growth, excellent biomass yield, and high lipid and carbohydrate contents. With their huge potential, algae are expected to surpass the first and second generation feedstocks. Only a few thousand algal species have been investigated as possible biofuel sources, and none of them was ideal. This review summarizes the current status of algal biofuels, important steps of algal biofuel production, and the major commercial production challenges.

In the present study, nanocellulose was extracted from palm leaves to synthesize nanocellulose/chitosan nanocomposites for the removal of dyes from textile industrial wastewater. Nanocellulose is of interest in water purification technologies because of its high surface area and versatile surface chemistry. Following bleach, alkali, and acid treatments on palm leaves, nanocellulose is obtained as a white powder. The produced nanocellulose was investigated. The adsorption capacity of chitosan, nanocellulose, and novel synthetic nanocellulose/chitosan microbeads (CCMB) for direct blue 78 dye (DB78) removal was studied. A series of batch experiments were conducted in terms of adsorbent concentration, mixing time, pH, dye initial concentration, and nanocellulose concentration in synthetic microbeads. The CCMB was characterized by using physicochemical analysis, namely Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), zeta potential analysis, and Fourier-transform infrared spectroscopy (FTIR). It was found that the surface area of synthetic CCMB is 10.4 m²/g, with a positive net surface charge. The adsorption tests showed that the dye removal efficiency increases with an increasing adsorbent concentration. The maximum removal efficiencies were 91.5% and 88.4%, using 14 and 9 g/L of CCMB-0.25:1. The initial dye concentrations were 50 and 100 mg/L under acidic conditions (pH = 3.5) and an optimal mixing time of 120 min. The equilibrium studies for CCMB-0.25:1 showed that the equilibrium data were best fitted to Langmuir isothermal model with R² = 0.99. These results revealed that nanocellulose/chitosan microbeads are an effective eco-adsorbent for the removal of direct blue 78 dye and provide a new platform for dye removal.

Poly(o-anthranilic acid) emeraldine salt (PANA-ES) as a conjugated semiconductor polymer has been synthesized in an acidic medium based oxidative polymerization route. The identification of the PANA-ES powder has been carried out using the following techniques: FT-IR and UV-Vis. SEM has been used to investigate the morphology of the resulting PANA-ES powder. The structural properties of the resulting nanostructured PANA-ES thin film have been investigated by X-ray diffraction (XRD). The analysis of the spectral behavior characteristics of the nanostructured PANA-ES thin film, in the absorption region, displayed a direct and indirect allowed transition, and the fundamental energy gaps were estimated as (1.89, 3.24 eV) and (2.35, 4.06 eV), respectively. A hybrid (polymer/inorganic) heterojunction device built on PANA-ES (deposited by the spin coating technique onto a p-Si single crystal wafer) was fabricated. The dark I–V characteristics were determined at different temperatures in the range from 298 to 386 K of the Au/PANA-ES/p-Si/Al heterojunction diode. The device showed rectification behavior and an ideality factor of 85 at ±2 V and 3.229 determined at room temperature. Under the following different light intensities: 10.1, 15.3 and 20.5 W m⁻², the Au/PANA-ES/p-Si/Al showed photovoltaic performance data with a short circuit current (I_sc) and open circuit voltage (V_oc) of (0.09 mA 1,41 mV), (0.16 mA, 176 mV) and (0.26 mA and 211 mV), respectively. The filling factor (FF) and electrical conversion efficiency (η) of the Au/n-PANA-ES/p-Si/Al device were found to be 0.205 and 6.07%, respectively.