**1. Introduction**

The capability of several human activities, like industry and mining, has expanded throughout the last decades [1], which has led to a similar pace of improvements in membrane technology for separation. Drinking water treatment processes have developed to the point of requiring more advanced pretreatment processes [2]. Nanofiltration (NF) might function as a pretreatment for reverse osmosis desalination [3], as it can remove hardness, specific heavy metals, and reduce the salt content of feed water [4].

**2. Methodology**

membranes.

following signals:

**2.1. Polymers and monomers**

Polysulfone (PS purity > 99%), polyether sulfonyl (PES; purity > 99%), piperazine (PP; purity > 99%), and 1,3,5-Benzenetricarbonyl chloride (TMC; purity > 98%) were obtained from Sigma-Aldrich. Chiltepin pepper extract [9] (capsaicin extract) was obtained in the laboratory as a source of the capsaicin molecule (**Figure 2**). This extract was used to prepare nanofiltration

Development, Characterization, and Applications of Capsaicin Composite Nanofiltration…

http://dx.doi.org/10.5772/intechopen.76846

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To corroborate the extraction of capsaicin, infrared spectroscopy was performed, showing the

• tension vibration for N-H present on the amide group, shown at 3381.8 cm−1; this signal hides within the O-H functional group, which has a range from 3400 to 3200 cm−1;

at 721.66 cm−1.

**Figure 2.** Chemical structure of the monomers for preparation nanofiltration composite membranes: piperazine,

at 1464.28 cm−1;

bending; and

• vibration departing from tension on C-H at alkene located at 3010.36 cm−1;

• vibration through tension for C = O for the amide group at 1744.74 cm−1; • vibration through stretching on C = O of the amide group at 1652.78 cm−1;

• C-H vibration corresponds to methylene alkanes, at 2924.8 cm−1; • methylene symmetrical tension for C-H present at 2853.77 cm−1;

• vibration through the asymmetrical bending of CH<sup>2</sup>

• the signal at 1374.7 cm−1, corresponding to a CH3

• an asymmetrical deformation of CH<sup>2</sup>

capsaicin and 1,3,5-benzenetricarbonyl chloride (TMC).

In addition, one of the main problems faced by desalination processes is the inevitable appearance of biofouling on its membranes [5, 6]. This causes problems such as decreases in permeate flux and salt rejection, as well as an increase in transmembrane pressure [7]. In an effort to reduce the most damaging effects of biofouling, there have been many studies for testing numerous anti-fouling agents and solutions added during membrane fabrication. However, not all these attempts include organic-based preparation, suggesting that there may be possible hazards for human health, after consumption [8, 9]. Pepper extract, the source of the capsaicin molecule, has proven to limit bacterial growth [10]; therefore, its addition during the membrane fabrication process may help control biofilm formation on the membrane surface.

In this study, nanofiltration membranes were prepared (**Figure 1**) for brackish water treatment. It is desirable for the desalination membranes to have hydrophilic properties, as this usually correlates with the tendency of a membrane for allowing water to permeate instead of rejecting it (hydrophobic) [11]. Contact angle measurements are usually carried out to determine the degree of hydrophilicity or hydrophobicity of a surface [12]. This study includes an analysis of the fabrication, as well as the characterization of four nanofiltration membranes, before and after their performance testing on a cross-flow module, operated with an aqueous salt solution to determine salt rejection. Membrane characterization is also performed through atomic force microscopy (AFM) and attenuated total reflectance infrared spectroscopy (ATR-IR) [13]. Membranes prepared with capsaicin will later be assessed for their anti-biofouling properties, to evaluate whether they are resistant to biofouling by seawater microorganisms.

**Figure 1.** Scheme of composite membrane.
