Mulch films increase soil temperature, maintain soil moisture, improve water and fertilizer absorption, and reduce weed growth. This work studied a mulching film made using polyvinyl alcohol (PVA) and lignin extracted from empty fruit bunches (EFBs). The mulch films were investigated for opaqueness, biodegradation, water-solubility, absorption, and mechanical properties. Life cycle assessment (LCA) and cost estimate analysis were conducted. The composite mulch film-PVA solution was blended with 6% EFB lignin in dimethyl sulfoxide (DMSO) solution using five different amounts (0, 20, 40, 60, or 80 wt% lignin). The results showed that increasing the amount of lignin increased the film’s water solubility, moisture content, and biodegradability. At the same time, water absorption tended to decrease. Consequently, the light transmittance of the film was reduced, which had a positive effect on preventing soil weed growth. Tests of the mechanical properties showed that 60% lignin in the PVA film had the highest tensile strength (16.293 MPa). According to the LCA studies and cost estimation, the lignin-mixed PVA film had the lowest impact and was cheaper than the commercial mulching film. The results suggested that it is possible to blend polyvinyl alcohol polymer with lignin to improve biodegradability up to 25.47% by soil burial and 32% by water solubility.

Overcoming the oxidation stability of biodiesel has been a significant challenge, especially after an extended storage period. To test a major factor affecting biodiesel quality, eight different conditions consisting of water at a concentration of 500 ppm and tert-butylhydroquinone (TBHQ) concentrations of 500, 1000, and 2000 ppm, in combination, were added to palm biodiesel, with no-water-added treatment as the control. Samples were kept in dark storage and air-limited at room temperature for 52 weeks with an initial carbon residue of 0.05 wt%. Every sample was periodically taken for property examination, which included the percentage of fatty acid methyl ester (FAME), iodine value (IV), kinematic viscosity (KV), acid value (AV), and oxidation stability. The properties of the samples with 500 ppm of water-added biodiesel exhibited the most significant degradation, even though oxidation stability (starting from 43.37 h) remained higher than 10.00 h after 32 weeks. The IV dropped 48.43% from 49.92 to 25.56 g I₂/100 g. The KV increased 6.14% from 4.56 to 4.84 cSt. The AV rose from 0.45 to 1.09 mg KOH/g. Biodiesel with 2000 ppm TBHQ added was stable for 22 weeks, with all properties under standard values. However, biodiesel in the same condition but with water contamination, its stability was reduced to 16 weeks.

We investigated the synthesis and characterization of biodegradable films composed of poly (lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT), with lignin as a natural additive and dicumyl peroxide (DCP) as a compatibilizer. The PLA/PBAT ratio of 70:30 was optimized and the DCP was incorporated at different concentrations to enhance interfacial adhesion. The effects of lignin addition (0.005–0.02%) on the mechanical, thermal, and biodegradation properties were evaluated using SEM, FTIR, XRD, and TGA analyses. The optimal formulation had improved tensile strength, elongation at break, and thermal stability, with the highest degradation rate of 44.22% after 90 days of soil burial. Life cycle assessment using SimaPro software (SimaPro 9.1.1.1) and ReCiPe 2016 Midpoint indicated that the film containing 0.005% lignin had the lowest environmental impact. The primary environmental concerns were marine and freshwater ecotoxicity, associated with solvent use. Based on the results, incorporating small amounts of lignin enhanced the biodegradability and reduced the environmental footprint of the PLA/PBAT films, highlighting their potential for sustainable packaging applications.

Wastewater containing heavy metals and dyes poses serious environmental risks. This study developed a multifunctional composite by coating polyurethane foam (PUF) with milled activated carbon (mAC) and a zirconium-based metal–organic framework (Zr-MOF) for the simultaneous removal of hexavalent chromium (Cr(VI)) and Congo red (CR). The composite was synthesized using a hydrothermal method to grow Zr-MOF on the surface. The SEM analysis confirmed the successful incorporation of mAC and surface modification with Zr-MOF, which resulted in increased surface roughness and porous morphology. XRD and FTIR confirmed the presence of organic ligands connected to the metal structure and the functional groups of each component in composite materials. The optimum conditions for Zr-MOF/mAC/PUF adsorption (nearly 100% removal) in the binary Cr(VI)/CR solution (50 mg/L each) were 25 °C, pH 9, and 150 rpm for 24 h. The Zr-MOF/mAC/PUF was hydrophilic with a swelling ratio of 2.64 g/g. The thermodynamic investigation of Zr-MOF/mAC/PUF resulted in 141.6218 kJ/mol for Cr(VI) and 166.111 kJ/mol for CR of ΔH° (rapid adsorption), negative ΔG° (spontaneous adsorption), a high positive value of ΔS° (disorder structure) and low activation energy (approximately 2.5 to 2.8 kJ/mol). After analyzing the isotherm and reaction kinetics, the possible mechanism could be endothermic physicochemical adsorption and pseudo-second-order kinetic behavior, with electrostatic attraction and diffusion control. The study of 6-times-reused Zr-MOF/mAC/PUF adsorption identified as a decrease of 7.55 percentage point without changing notable morphology and functional groups, based on SEM and FTIR.

Biodiesel production from waste cooking oil (WCO) offers environmental and economic advantages but is constrained by degraded feedstock quality and unstable fuel properties. This study evaluates an integrated upgrading strategy combining reaction pathway selection, adsorption-based purification, and feedstock blending to produce fuel-grade biodiesel. WCO was pretreated by moisture removal and acid esterification using H₂SO₄ to reduce free fatty acids. Transesterification was conducted in a temperature-controlled batch reactor at 60 °C using 6:1–12:1 methanol-to-oil mass ratios, 1.0–2.0 wt% KOH catalyst loadings, and 60–120 minute reaction times. The maximum FAME content achieved was 93.94 wt% at 6:1 methanol ratio, 1.5 wt% KOH, and 90 min reaction time. Post-reaction upgrading was performed via batch adsorption using activated carbon (0.5–2 wt%, 60 °C) and silica gel (3 wt%, 112 °C). Adsorption improved FAME content to 94–95 wt% (maximum 95.3 wt% with silica gel) and reduced acid value and carbon residue. However, oxidation stability decreased slightly after adsorption (from 4.20 to 4.05 h), indicating partial removal of natural antioxidants. GC–MS analysis confirmed the dominance of methyl esters and the reduction of minor impurity-related peaks after purification. To comply with multi-parameter fuel requirements, WCO was blended with palm olein prior to conversion at ratios of 100:0 to 10:90 (w/w). Full EN 14214 compliance (FAME ≥ 96.5 wt%) was achieved at ≥50% palm olein, with oxidation stability of 10.2 h at a 10:90 ratio. These findings demonstrate that adsorption enhances compositional purity, whereas feedstock blending is decisive for restoring oxidative stability and achieving robust, fuel-grade biodiesel.