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Reverse osmosis (RO) desalination is a technology that is commonly used to mitigate water scarcity problems; one of its disadvantages is the bio-fouling of the membranes used, which reduces its performance. In order to minimize this problem, this study prepared modified thin film composite (TFC) membranes by the incorporation of chitosan–silver particles (CS–Ag) of different molecular weights, and evaluated them in terms of their anti-biofouling and desalination performances. The CS–Ag were obtained using ionotropic gelation, and were characterized by Fourier transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA) and dynamic light scattering (DLS). The modified membranes were synthetized by the incorporation of the CS–Ag using the interfacial polymerization method. The membranes (MCS–Ag) were characterized by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and contact angle. Bactericidal tests by total cell count were performed using Bacillus halotolerans MCC1, and anti-adhesion properties were confirmed through biofilm cake layer thickness and total organic carbon (%). The desalination performance was defined by permeate flux, hydraulic resistance, salt rejection and salt permeance by using 2000 and 5000 mg L−1 of NaCl. The MCS–Ag-L presented superior permeate flux and salt rejection (63.3% and 1% higher, respectively), as well as higher bactericidal properties (76% less in total cell count) and anti-adhesion capacity (biofilm thickness layer 60% and total organic carbon 75% less, compared with the unmodified membrane). The highest hydraulic resistance value was for MCS–Ag-M. In conclusion, the molecular weight of CS–Ag significantly influences the desalination and the antimicrobial performances of the membranes; as the molecular weight decreases, the membranes’ performances increase. This study shows a possible alternative for increasing membrane useful life in the desalination process.

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Reverse osmosis (RO) desalination is considered a viable alternative to reduce water scarcity; however, its energy consumption is high. Photovoltaic (PV) energy in desalination processes has gained popularity in recent years. The temperature is identified as a variable that directly affects the behavior of different parameters of the RO process and energy production in PV panels. The objective of this study was to evaluate the effect of temperature on energy consumption and polarization factor in desalination processes at 20, 23, 26 and 30 °C. Tests were conducted on a RO desalination plant driven by a fixed 24-module PV system that received spray cooling in the winter, spring and summer seasons. The specific energy consumption was lower with increasing process feed temperature, being 4.4, 4.3, 3.9 and 3.5 kWh m−3 for temperatures of 20, 23, 26 and 30 °C, respectively. The water temperature affected the polarization factor, being lower as the temperature increased. The values obtained were within the limits established as optimal to prevent the formation of scaling on the membrane surface. The spray cooling system was able to decrease the temperature of the solar cells by about 6.2, 13.3 and 11.5 °C for the winter, spring and summer seasons, respectively. The increase in energy production efficiency was 7.96–14.25%, demonstrating that solar cell temperature control is a viable alternative to improve power generation in solar panel systems.

Microalgae are considered sources of compounds of high nutritional value. This study determined whether 400 μE/m2/s (HL) and 80 μE/m2/s (LL) light intensities and algal medium (AM) and f/2 Guillard medium (f/2GM) influence kinetic parameters, moisture, ash, lipids, carbohydrate, protein, amino acid, vitamins contents of the microalgae Nannochloropsis oculata and Porphyridium cruentum. N. oculata recorded the highest cell density of 341.64 ± 2.36 × 106 cells/ml under HL in AM, while P. cruentum achieved 56.60 ± 1.33 × 106 cells/ml under LL in f/2GM. The highest lipids content was 28.66 ± 0.14% for N. oculata, and 13.40 ± 0.25% for P. cruentum, both under LL in f/2GM. The higher carbohydrates content was obtained in AM, 30.41 ± 1.10% at LL and 47.57 ± 1.52% at HL for N. oculata and P. cruentum respectively. The protein content was 34.53 ± 1.33% and 26.03 ± 1.00% both under HL in AM for N. oculata and P. cruentum respectively. In terms of amino acid and vitamins composition, only N. oculata presented high content of essential amino acids and vitamins α‐tocopherol, β‐sitosterol and β‐carotene, based on these results, N. oculata could be recommended as a rich source of lipids, protein, amino acid and vitamin and P. cruentum for their high carbohydrate.

This work presents the morphology and characterization of chitosan nanoparticles crosslinked with lecithin in the form of nano-onions obtained by an easy, economical, and possibly scalable method from a polymeric precursor known as chitosan. The creation of new products by using shrimp waste is a fundamental factor in avoiding water pollution. These materials have a positive impact as they add value to waste, and they provide the opportunity to decrease pollution. Chitosan nano-onions were synthesized by an environmentally friendly, easy, and inexpensive method using chitosan as a natural source. Chitosan nano-onions (CSNO) were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and specific surface area (SSA). The nano-onions characterization obtained by FTIR shows the presence of carbonyl groups at a wavenumber of 1752.12 cm–1, while the phosphate groups attributed to lecithin are observed at 1156.88 cm–1. XRD analysis confirmed an amorphous structure, while SEM images presented a globular morphology with concave surfaces. TEM analysis showed that the nano-onions are congregated in a unique structure that includes nanotubes. The CSNO average diameter by DLS was 442.5 nm with an octagonal arrangement, and a polydispersity index (PDI) of 0.532 and 31.9 mV. The average size of CSNO, the PDI, and the value of zeta potential were indicators of a stable dispersion with a specific superficial area measured by the Brunauer-Emmett-Teller (BET) method of 1.4 m2 g–1. The results of the chitosan-lecithin nano-onions characterization indicate changes in the surface of the material with a larger total surface area and pore structure, compared to that of pure chitosan. According to the results of the CHNO characterization, they could be used as adsorbents for contaminants and they also have a potential application in the biomedical area, mainly as drug encapsulation material.