Volatile organic compounds (VOCs) comprise various organic chemicals which are released as gases from different liquids or solids. The nature and impact of the health effects are dependent on the VOCs concentrations and, also, on the exposure time. VOCs are present in different household, industrial or commercial and products, but their accumulation in air and water has primarily gained attention. Among VOCs, trichloroethylene and vinyl chloride are the most toxic and carcinogenic compounds. In order to improve the indoor air and water quality, VOCs can be removed via efficient approaches involving nanomaterials, by using techniques such as adsorption, catalysis or photocatalysis. In the recent years, the development of manufacturing procedures, characterization techniques and testing processes has resulted in the growth of na-nomaterials obtaining and applications, creating great possibilities and also a tremendous prov-ocation in applying them for highly efficient VOCs removal. This review is intended to contrib-ute to the improvement of awareness and knowledge on the great potential that nanomaterials have in VOCs removal, in order a to improve indoor and outdoor environment, but also the worldwide water sources.

Volatile organic compounds (VOCs) released in air represent a major potential for environmental pollution. Capture methods based on activated biochar have attracted attention because of their low cost and for the high removal capacity of the material due to its physical and chemical properties. In this paper, activated biochars were developed and their adsorption performance for VOC capture was evaluated. In the first step, biochars derived from rapeseed cake (RSC) and walnut shells (WSC) were obtained through a carbonization process and then were activated using basic/acid agents (KOH/H₂SO₄) to increase their performance as adsorbents. Acetone and toluene were used as the VOC templates. The adsorption capacities of toluene and acetone for non-activated biochars were reduced (26.65 mg/g), while that of activated biochars increased quite significantly, up to 166.72 mg/g, and the biochars activated with H₂SO₄ presented a higher adsorption capacity of VOCs than the biochars activated with KOH. The higher adsorption capacity of biochars activated with H₂SO₄ can be attributed to their large surface area, and also to their larger pore volume. This activated biochar adsorbent could be used with good results to equip air purification filters to capture and remove VOCs.

A major problem that limits the use of biodiesel is maintaining the fuel at the specified standards for a longer period. Biodiesel oxidizes much more easily than diesel, and the final oxidation products change its physical and chemical properties and cause the formation of insoluble gums that can block fuel filters and the supply pipes. This instability of biodiesel is a major problem and has not yet been satisfactorily resolved. Recently, the use of biodiesel has increased quite a lot, but the problem related to oxidation could become a significant impediment. A promising and cost-effective approach to improving biodiesel’s stability is to add appropriate antioxidants. Antioxidants work better or less effectively in different biodiesel fuels, and there is no one-size-fits-all inhibitor for every type of biodiesel fuel. To establish a suitable antioxidant for a certain type of biodiesel, it is necessary to know the chemistry of the antioxidants and factors that influence their effectiveness against biodiesel oxidation. Most studies on the use of antioxidants to improve the oxidative stability of biodiesel have been conducted independently. This study presents an analysis of these studies and mentions factors that must be taken into account for the choice of antioxidants so that the storage stability of biodiesel fuels can be improved.

By loading Cr and Zn on 13X zeolite, efficient nanocatalysts were prepared; they were characterized by different techniques and used for corn cobs pyrolysis to produce bio-oil. The corn cobs biomass (CCB) was washed with sulfuric acid 0.1 M, and the characteristics of the pretreated biomass (PTCCB) were analyzed. Pyrolysis was performed at different catalyst-to-biomass ratios (C/B), and the composition of the obtained bio-oil was determined. The results showed that the crystallinity of the nanocatalysts was slightly lower than that of the pattern 13X zeolite. The surface observation of the nanocatalysts showed the presence of pores and particles, which are quite evenly dispersed on the surface, and no difference was observed in the morphology of the Zn/13X zeolite and Cr /13X zeolite nanocatalysts. In comparison to 13X zeolite, the morphological changes, metal dispersion, and surface area decrease of both Zn/13X and Cr/13X zeolite nanocatalysts could be observed. Pyrolysis tests demonstrated that the use of Zn/13X zeolite and Cr/13X zeolite nanocatalysts could be very profitable to obtain a high conversion to hydrocarbons of the compounds containing oxygen, and consequently, the quality of the bio-oil was improved.

Nanocomposites based on 13X zeolite (13XZ), calcium oxide (CaO) and metal zinc particles (Zn) were prepared. The resulting nanocomposites were characterized by different techniques. Then, a comparative study on catalytic and noncatalytic pyrolysis of biomass waste was performed to establish the influence of nanocomposites used as catalysts on the yields and characteristics of liquid and solid products. Residual rapeseed biomass (RRB) was employed for pyrolysis experiments and a fixed bed reactor was used. By introducing CaO and metal zinc particles into 13X zeolite mass, the surface area (S_BET) of nanocomposites was reduced, and this decrease is due to the introduction of nano-calcium carbonate and nano-zinc particles, which occupied an important space into zeolite structure. By adding CaO to 13XZ, the pore structure was changed and there was a decrease in the micropores volume. The analysis of the pore area distribution showed a hierarchical pore structure for nanocomposites. The elements composition showed that the main elements contained in nanocomposites are Si, Al, Ca and Zn, confirming the preservation of the zeolite structure. Using these nanocomposites as catalysts in pyrolysis process, the residual biomass could be valorized, producing bio-oil and biochar for the management and sustainability of this low-value waste.