Microwave Assisted Preparation of Calcium Hydroxide and Barium Hydroxide Nanoparticles and Their Application for Conservation of Cultural Heritage Khaled M. Saoud*, Imen Ibala, Dana El Ladki, Omar Ezzeldeen, Shaukat Saeed Liberal Arts and Science Program, Virginia Commonwealth University in Qatar Doha, Qatar *Corresponding Author: Dr. Khaled M. Saoud; Email: s2kmsaou@vcu.edu , Ph. +974 6603 7810 Abstract. In this paper, we present the microwave-assisted synthesis and characterization of alkaline nanomaterials for the preservation of cultural heritage. Calcium and barium hydroxide nanomaterials suspended in aqueous as well as alcoholic medium were applied on different samples to check their effectiveness. The effect of treatment was measured using pH value and alkaline reserve test. The alkaline reserve test results indicate improvement in the alkaline buffer with significant reduction in acidity of the papers and improvement in pH value of the surfaces. Ethanol was found as best solvent on the basis of suspension of nanoparticles, pH value and ease of application through spray gun. Accelerated ageing test revealed that the reinforcement effect of these nanomaterials persisted throughout the ageing. All the results converged in individuating these nanometric particles as an innovative, completely compatible, and efficient material for the consolidation of old and new paper surfaces. Keywords: Cultural heritage, Nanomaterials, paper deacidification, alkaline reserve, Calcium hydroxide, Barium hydroxide. Introduction The deterioration of cultural heritage objects is one of the most critical problems in the humanities and social sciences today. Preserving and restoring the cultural artifacts is crucial to maintain history and culture of nations and keeps it alive for future generations. Many of the hundred years old books are currently too fragile to handle due to the presence of acidic content in the paper. In 1830, alum-rosin sizing was introduced to the paper-making process to speed up production [1]. Unfortunately, sulfuric acid is formed during this process which attacks the cellulose fibers in the paper [2]. There are other factors such as oxidation, temperature and humidity, exposure to light, air pollutants, and the amount of use also contribute to the destruction of the books [3]. Preservation involves a wide range of activities, including the general conservation of important and rare books and documents, and handling procedures [4]. Many techniques depend on manual operations are time-consuming and often require skilled practitioners [5]. One of the strategies to deal with acid book preservation- problem is the deacidification of the paper with suitable materials [6]. Sheets of paper are either dipped in or sprayed with a solution containing one or more alkaline compounds [7]. Alkaline treatment usually magnesium or calcium carbonates and the solvents can be aqueous or non-aqueous. Unfortunately, water dispersions of commercially available