The issue of environmental pollution has become a hot issue in today's world. Environmental pollution, mainly caused by toxic chemicals, includes air, water, and soil pollution. This pollution results not only in the destruction of biodiversity, but also the degradation of human health. Pollution levels that are increasing day by day need better developments or technological discoveries immediately. Nanotechnology offers many advantages to improve existing environmental technologies and create new technology that is better than current technology. In this sense, nanotechnology has three main capabilities that can be applied in the fields of environment, including the cleanup (remediation) and purification, the detection of contaminants (sensing and detection), and the pollution prevention.

Significant concerns over energy security and environmental impact reduction will drive all stakeholders to generate proper alternative energies. Biodiesel is a prospective cleaner-burning biofuel that can contribute on addressing these concerns globally. Presently, pure biodiesel (B100) application is still facing several obstacles, principally in terms of its cold flow properties. Improvement in cold flow behavior parameters is the solution to promoting biodiesel implementation at a higher percentage and wider environmental temperature range. This study provides a detailed review of several improvement methods, both physical, chemical, and biological, from various scientific sources, to elevate the cold fluidity characteristics of biodiesel. The investigated methods convincingly offer proper enhancement in the cold flow properties of biodiesel. Mostly, this improvement is accompanied by an alleviation in oxidation stability, cetane number, and/or viscosity. However, the skeletal isomerization method presents promising cold fluidity refinement with minimal reduction in other physical properties. Therefore, the continuous development of these methods promises global sustainable application of high-quality biodiesel.