Deproteinization of Nonammonia and Ammonia Natural Rubber Latices by Ethylenediaminetetraacetic Acid

N Moonprasith,A Poonsrisawat,K Suchiva,S Loykulnant,V Champreda,C Kongkaew

doi:10.1155/2017/1516945

Abstract

Deproteinized natural rubber (DPNR) was made from sodium hydroxymethylglycinate latex (SH-latex) and ammonia latex (NH3-latex) by mixing with different forms of ethylenediaminetetraacetic acid (EDTA) in the presence of sodium dodecyl sulfate (SDS). The mixtures were stirred at room temperature followed by centrifugation to separate the denatured proteins. The optimized reaction contained 0.01 wt% ethylenediaminetetraacetic acid tetrasodium (EDTA-4Na) with 1% SDS. The nitrogen contents of the DPNR from SH-latex and NH3-latex were reduced to 0.005 wt% and 0.008 wt%, respectively, compared to 0.551 wt% in the starting SH-latex and 0.587 wt% in the NH3-latex. SDS-PAGE analysis and FT-IR spectroscopy showed decomposition of latex proteins to peptides of smaller molecular weight. Physical properties of the DPNR rubber were studied. The novel EDTA-4Na treatment is considered an effective deproteinization method with potential application on both ammonia and nonammonia preservative systems.

Highlights

Natural rubber (NR) field latex (Hevea brasiliensis) contains 30–40% rubber by weight dispersed as rubber latex particles in water with some minor nonrubber constituents such as proteins, lipids, carbohydrates, sugars, and metal ions
The Deproteinized natural rubber (DPNR) latex was prepared by treating fresh natural rubber (FNR) latex with ethylenediaminetetraacetic acid sodium (EDTA-Na), ethylenediaminetetraacetic acid disodium (EDTA-2Na), ethylenediaminetetraacetic acid trisodium (EDTA-3Na), and ethylenediaminetetraacetic acid tetrasodium (EDTA-4Na) at various concentrations (0.05, 0.10, 0.20 wt%) in the presence of 1 wt% sodium dodecyl sulfate (SDS) at room temperature for 1 h with continuous stirring
In order to determine the optimal dosage of EDTA-4Na on deproteinization, the nonammonia and ammonia latices were incubated with EDTA-4Na at various concentrations (0.05, 0.10, and 0.20 wt%) in the presence of 1 wt% SDS at room temperature for 1 h

Summary

Introduction

Natural rubber (NR) field latex (Hevea brasiliensis) contains 30–40% rubber by weight dispersed as rubber latex particles in water with some minor nonrubber constituents such as proteins, lipids, carbohydrates, sugars, and metal ions. The protein component of the natural rubber latex particles is believed to be exclusively associated with the particle surface as an adsorbed layer [1]. NR was effectively deproteinized in the latex stage by enzymatic degradation which removed proteins present on the surface of the rubber particle [4, 5]. This resulted in marked decrease in the nitrogen content of NR to less than 0.02%, which was approximately 5% of the starting material [6,7,8]. NR treatment with urea and saponification led to reduction in the total nitrogen content to lower than 0.02 wt% within 1 hour under suitable conditions [6]

Methods

Results

Conclusion