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Palmyra palm fruit fibers have the properties to be used as an alternative raw material of cellulosic pulps for papermaking.Acid and alkali pulping were investigated by using nitric acid and caustic soda on a laboratory scale, with the purpose of producing printing or writing grade pulp. The chemical composition of fiber strands from palmyra palm fruits were examined, such as holocellulose, cellulose, pentosan, lignin and extractives. The yields of acid and soda pulps were below 40%. The main physical and mechanical properties of hand sheets produced from acid and soda processes were evaluated on 80 g/m2 test sheets as functions of the following parameters: tensile index, tear index, and brightness. The mechanical properties of soda pulps were developed by twin-roll press while it was not necessary to fibrillate acidic pulps through the beating step. The soda pulp sheets presented a lower brightness than that of acidic pulp sheets. The mechanicaland physical properties of the acidic and alkaline pulps verified that they were of an acceptable quality for papermaking.

Increasingly stringent environmental regulations and increasing input costs negatively affects the sustainability and competitiveness of the pulp and paper industry. As a result, it has become necessary that broader strategies aimed at helping the industry to improve the environment performance whilst also reducing the operation costs are initiated. Recovering water and chemical from the bleach plant effluent streams could be one of such initiatives. In this paper, a preliminary techno-economic assessment of recovering water and caustic soda from alkaline bleach plant effluent using ultrafiltration and reverse osmosis membrane systems is presented. The scope of this work included; assessing the practicality and the economic performance of this membrane process. In terms of the practicality, the data acquired revealed that the proposed concept can only be applied to the alkaline effluents from the alkaline extraction stage, where caustic soda, oxygen, and peroxide are used as the pulp bleaching chemicals. Economic performance of this membrane system, however, is dependent on the effluent flow rates and the amount of water recovered. To be economically viable, the flow rates must higher than 480 m 3 /day and water recovery rate need to be higher than 70%. At this optimum effluent flow and water recovery rates, the process cost is approximately R 19/m 3 . Depending on the flow rates, the investment cost is in the range of R 5–25 million and the payback time is between 3 and 4 years. However, motivations of caustic recovery should be based on environmental rather than economic benefits. Mills can use the detailed information/data acquired in this study to determine whether it would be beneficial for them to implement this type of integrated waste management strategy in their processes. [ABSTRACT FROM AUTHOR]

The chlor-alkali process is a widely used electrolytic process that yields chlorine and caustic soda. It has been in use since the 19th century and is a primary industry in the United States, Western Europe, and Japan. There are three primary electrolytic processes for producing chlorine and caustic soda: the diaphragm cell process, the mercury cell process, and the membrane cell process. The first two have been used for over 100 years; the latter was developed in the past 60. The two oldest methods are used the most throughout the world and have been proven to be the most environmentally unfriendly through their use of asbestos and mercury, respectively. The membrane cell process is a superior method in its energy efficiency and lack of harmful chemicals. This article reviews the history of each method, addresses changes in its modern technology and use, and discusses the emissions and outputs of the processes. [ABSTRACT FROM AUTHOR]

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In this study, a two-stage diffusion dialysis (DD) and electrodialysis (ED) system for the removal and recovery of sodium hydroxide from industrial wastewater were investigated. The study was carried out at laboratory scale using food industry wastewater. Sodium hydroxide is commonly used as principal strong base by various chemical industries. The processed wastewater therefore enhances the pH levels of receiving water bodies that affects the physiological functions of aquatic organisms, plants, and makes the water inappropriate for human consumption. 1.0-μm PTFE (Advantec, USA), forward osmosis (FO) (Hydration Technology Innovation) membranes, platinum coated over titanium anode, and graphite cathode were used in this study. In the first stage of the DD process, NaOH from the feed solution (FS) i.e. wastewater to draw solution (DS) i.e. deionized water (DI) was carried out through PTFE membrane in a diffusion cell. The initial concentration of NaOH in the FS was from 1 to 3 M and in the first step, 60 to 62% of NaOH was diffused from the FS to DS. In the second step of the DD process, further 48 to 50% NaOH was transferred from the FS to DS and overall 80 to 83% NaOH was removed from the FS. In the second stage, the DS collected from diffusion cell was transferred to the ED cell as the FS for further treatment and recovery of caustic soda. During the ED process, 15.0 V was applied for 5.0 h batch time. Sodium cations were transported from the FS to DS under the influence of electric potential through FO membrane and up to 44% of NaOH was recovered. [ABSTRACT FROM AUTHOR]

In the cyanidation process, copper–gold deposits containing significant amounts of cyanide soluble copper can lead to high cyanide consumption with low gold extraction. The significant levels of weak acid dissociable (WAD) cyanide must then be destroyed prior to tailings disposal. This increases the cost to the gold mining companies to cover both the extra cyanide consumption in the leaching stage and the additional cost for cyanide recovery/destruction. Therefore, in this study, a selective cyanide leaching process of gold over copper from copper–gold concentrate (also see Oraby and Eksteen, 2014 ) containing 490 g/t Au and 0.97% Cu present as metallic copper, oxides and sulfides has been investigated. To decrease the cyanide consumption, cyanide is added into the leach solutions to maintain a ratio of cyanide to total reactive copper (CN/Cu) below 2. At low CN/Cu ratio, increasing the pH of solution can lead to the precipitation of solubilized copper as CuO/Cu(OH) 2 , releasing cyanide ions for further both gold and copper dissolution. A comparison of leaching gold in cyanide–caustic, cyanide–ammonia and conventional cyanidation processes has been made. Higher gold extraction and lower copper concentration in the final leach was achieved in the cyanide–caustic system than in either the cyanide–ammonia or conventional cyanidation processes. The effects of the caustic soda (pH) concentration or cyanide concentration on gold extraction and copper suppression have also been studied. The results show that at high pH (>12), the gold dissolution rate increases significantly in solutions containing caustic soda and cyanide at zero, or very low free cyanide concentration. [ABSTRACT FROM AUTHOR]

The study aimed to produce activated carbon by gradual heating to about 550°C for 4hr. The mixture consist of 1:2 ( residual petroleum: sodium hydroxide) The residual petroleum used was the atmospheric residual from Hammam AL-AIil in the northen of Iraq. The prepared activated carbon gives good results for the adsorption of iodine No. and methylene blue in comparson to synthetic carbon . Another characters for activated carbon were studied like ash content and density.