A Thermal Chemical Reaction System for Natural Gas Hydrates Exploitation

The methodology of using CO2 to replace CH4 to recover the natural gas hydrates (NGHs) is supposed to avoid geological disasters. However, the reaction path of the CH4–CO2 replacement method is too complex to give satisfactory replacement efficiency. Therefore, this study proposed a thermochemical reaction system that used the heat and the nitrogen released by the thermochemical reactions to recover NGHs. The performance of the thermochemical reaction system (NaNO2 and NH4Cl) regarding heat generation and gas production under low temperature (4°C) conditions was evaluated, and the feasibility of exploiting NGHs with an optimized formula of the thermochemical reaction system was also evaluated in this study. First, the effects of three catalysts (HCl, H₃PO₄, and NH2SO3H) were investigated at the same reactant concentration and catalyst concentration. It was confirmed that HCl as a catalyst can obtain better heat generation and gas production. Second, the effect of HCl concentration on the reaction was investigated under the same reactant concentration. The results showed that the higher the HCl concentration, the faster is the reaction rate. When the concentration of HCl was greater than 14 wt%, side reactions would occur to produce toxic gas; hence, 14 wt% was the optimal catalyst concentration for the reaction of NaNO2 and NH4Cl at low temperatures. Third, the heat generation and gas production of the thermochemical reaction systems were evaluated at different reactant concentrations (1, 2, 3, 4, 5, and 6 mol/L) at 14 wt% HCl concentration. It was found that the best reactant concentration was 5 mol/L. Finally, the feasibility of exploiting NGHs with the optimal system was analyzed from the perspectives of thermal decomposition and nitrogen replacement. The thermochemical reaction system provided by this study is possible to be applied to explore NGHs’ offshore.

Experimental Results to Design Lactic Acid for Carbonate Acidizing

Acidizing deep carbonate formations by Hydrochloric acid (HCl) is a complex task due to high reaction and corrosion rates. Mixing organic acids with HCl is a typical method to reduce the acid's reactivity and corrosivity. Lactic acid has not been investigated completely in the area of carbonate acidizing. Lactic acid has a dissociation constant similar to formic acid, which is approximately 10 times larger than acetic acid. Therefore, the objective of this work is to compare lactic/HCl blends with plain HCl and formic/HCl blends. Corrosion tests were conducted at high temperature on C-95 steel coupons to investigate associated corrosion damage. Coreflood tests were performed on Indiana limestone cores to mimic matrix acidizing treatment and to investigate amount of pore volumes required to breakthrough. All blends were prepared to be equivalent to 15 wt% (4.4 M) HCl for comparison. Lactic and formic acid concentrations were set to be (0.5 or 1 M), and HCl concentration was calculated as appropriate to reach a blend with strength of 4.4 M. In terms of corrosivity evaluation, blends of lactic and HCl acids showed a corrosion rate of up to 1.97 lb/ft2 at 300°F. The formic and HCl blend showed a corrosion rate of 1.68 lb/ft2 at the same temperature. The difference in corrosion rates between the two mixtures is due to molecular weight difference between lactic and formic acids. When both acids were prepared at 1 M, lactic acid blend required more HCl to be equivalent to 15 wt% HCl acid which was associated with an increase in corrosion rate. Coreflood results established acid efficiency curves for lactic/HCl acid blends. The curves highlighted the correlation between acid-core reactivity, injection rate, and dissolution pattern. Lactic/HCl blend was less reactive than formic/HCl mixture as the last required lower injection rate to obtain optimum pore volume to breakthrough at 300°F. Lactic/HCl blend was able to generate an optimum dissolution pattern as a dominant wormhole was shown on tested core plugs inlet face. This study expands the investigation of lactic acid utilization in carbonate acidizing. Major advantages rendered by using lactic acid with HCl include: (1) favorable dissolution pattern due to lactic acid being less reactive than HCl or formic acids, and (2) less corrosion rates comparing to HCl, that can reduce allocated costs for maintenance and replacements.

Glucohealth: The potential of porang (Amorphophallus muelleri) acid hydrolysed glucomannan as an inhibitor of SARS-CoV-2 interaction with ACE2

The novel SARS-CoV-2 that causing global pandemic COVID-19 known to enter the host cell using the hACE2 as cell receptor. SARS-CoV S1 protein cleaves the ACE2 receptor, then the S2 subunits facilitates the cell membrane fusion, the inhibition of S1-ACE2 interaction can help develop anti SARS-CoV-2 medication. Porang glucomannan is a polysaccharide known as immunomodulator but never reported as anti-virus by direct inhibition of viral entry. Glucohealth was developed to investigate its potential. Method: Glucohealth is a glucomannan hydrolysate (HGM) that made from porang (Amorphophallus muelleri). Hydrolysis was carried using HCl in different concentration (0.25N, 0.5N, 1N) then analyzed its inhibitor activity using ELISA kit. Result: Higher HCl concentration produced HGM with smaller average particle size and lower glucomannan content. However, ELISA studies showed that glucomannan, including its hydrolysates, have the potency to bind with S1 protein and inhibit the binding activity of S1-ACE2. Degraded glucomannan proven to have better bioactivity and able to interact with pathogen to inhibit its cell entry. This project should be a gateway for further biomedical study of glucomannan from Indonesia’s local tuber and new approach to produce more natural therapy against COVID-19.

Sequential Hydrothermal HCl Pretreatment and Enzymatic Hydrolysis of Saccharina japonica Biomass

This study investigated the production of fermentable sugars from carbohydrate-rich macroalgae Saccharina japonica using sequential hydrolysis (hydrothermal acid pretreatment and enzymatic hydrolysis) to determine the maximum reducing sugar yield (RSy). The sequential hydrolysis was predicted by three independent variables (temperature, time, and HCl concentration) using response surface methodology (RSM). Enzymatic hydrolysis (8.17% v/wbiomass Celluclast® 1.5 L, 26.4 h, 42.6 °C) was performed after hydrothermal acid pretreatment under predicted conditions (143.6 °C, 22 min, and 0.108 N HCl concentration). Using this experimental procedure, the yields of hydrothermal acid pretreatment, enzymatic hydrolysis, and sequential hydrolysis were 115.6 ± 0.4 mg/g, 117.7 ± 0.3 mg/g, and 183.5 ± 0.6 mg/g, respectively. Our results suggested that sequential hydrolysis of hydrothermal acid pretreatment and enzymatic hydrolysis was more efficient than their single treatment.

Exploitation of Kaolin as an Alternative Source in Alumina Production

The extensive consumption of aluminum, combined with the shortage of the existing raw materials, and particularly bauxite, necessitates the exploitation of alternative raw materials for the production of alumina. The present paper focuses on the possible use of kaolin, as an abundant, cheap and high-aluminum content raw material, in alumina production, via the application of the Aranda-Mastin technology in the leaching step. From this point of view, leaching experiments were conducted on untreated kaolin and thermally treated, metakaolin, applying atmospheric pressure, temperature of 90 °C and with an aqueous solution of a low HCl concentration as the leaching agent. Leaching, in the aforementioned conditions, is an industrially applied process, characterized by highly efficient aluminum dissolution in the case of metakaolin with low silicon dissolution at a short retention time, but with respectively lower achieved results for untreated kaolin. In order to raise the aluminum dissolution rate from untreated material, temporal and subsequently chemical intensification was applied. The analysis indicated a higher aluminum dissolution rate, up to 70%, with the application of a high acid concentration of leaching agent, performed for a long retention time that could be further improved.

Performance of sodium lignosulfonate as thickening additive in compositions for matrix acidizing of bottom hole zone

The work considers one of the promising directions for optimizing matrix acidizing using sodium lignosulfonate as a thickening agent. The mechanism of the interaction of acid solutions containing lignosulfonate with carbonate reservoirs is described. The use of sodium lignosulfonate in acid solutions solves several problems. Slowing the reaction rate allows the acid solution penetrate deeper into the formation, with maintaining the HCl concentration. The increased viscosity of the compositions increases the sweep efficiency of the bottomhole zone in the process of matrix acidizing. These two aspects increase the efficiency of matrix acidizing and the permeability of the bottomhole zone. In the course of this work, the chemical reaction rate of sodium lignosulfonate and hydrochloric acid solutions with carbonate core samples were evaluated. Sodium lignosulfonate in an acid solution reduces the dissolution rate of carbonate samples. It is assumed that slowing down the reaction rate allows the acid solution to form long high permeability channels which increases the efficiency of acidizing.

Phosphorous and Silica Recovery from Rice Husk Poultry Litter Ash: A Sustainability Analysis Using a Zero-Waste Approach

Phosphate rocks are a critical resource for the European Union, and alternative sources to assure the future production of a new generation of fertilizers are to be assessed. In this study, a statistical approach, combined with a sustainability evaluation for the recovery of materials from waste containing phosphorus (P), is presented. This work proposes a strategy to recover P and silica (SiO2) from rice husk poultry litter ash (RHPLA). The design of experiment (DoE) method was applied to maximize the P extraction using hydrochloric acid (HCl), with the aim to minimize the contamination that can occur by leachable heavy metals present in RHPLA, such as zinc (Zn). Two independent variables, the molar concentration of the acid, and the liquid-to-solid ratio (L/S) between the acid and RHPLA, were used in the experimental design to optimize the operating parameters. The statistical analysis showed that a HCl concentration of 0.34 mol/L and an L/S ratio of 50 are the best conditions to recover P with low Zn contamination. Concerning the SiO2, its content in RHPLA is too low to consider the proposed recovery process as advantageous. However, based on our analysis, this process should be sustainable to recover SiO2 when its content in the starting materials is more than 80%.

Evaluation of Surfactant Mixture for Supercritical Carbon Dioxide Foamed Acid in Carbonate Matrix Acidizing

The effectiveness of matrix acidizing using CO2 foamed acid is dependent on the duration of foam stability. This paper presents a supercritical CO2 foamed acid with a surfactant mixture to improve the foam stability in carbonate matrix acidizing. The experimental apparatus was developed to conduct foam-stability and wormhole-propagation tests under high-pressure and high-temperature (HPHT) conditions. The foam decay times of five types of surfactants were measured under atmospheric conditions. Trimax (blend of cocamidopropyl betaine, disodium cocoamphodiacetate, and amine oxide) and Aromox C/12W (coco bis-(2-hydroxyethyl) amine oxide) had a high foam decay time. The surfactant mixture was prepared using these two surfactants. The foam stability tests of the surfactant mixture were performed according to the HCl concentration, surfactant mixing ratio, and injection rate of HCl under HPHT conditions. As a result, the foam stability could be improved by adding an HCl concentration of 20% to the surfactant mixture. Wormhole-propagation tests were performed using Indiana and Indonesian limestones. Because of the supercritical CO2 foamed acid injection, dominant wormholes were formed in all the core samples; thus, the absolute permeabilities significantly increased. The results of the scanning electron microscopy/energy-dispersive x-ray spectroscopy and thin-section analyses revealed that the number of large pores with pore sizes of ≥0.5 mm increased by the injection of CO2 foamed acid. Therefore, the supercritical CO2 foamed acid with the surfactant mixture exhibited a high efficiency of matrix acidizing in carbonate reservoirs.

THE EXTRACTION OF EUCALYPTUS AS A NATURAL INHIBITOR FOR MILD STEEL IN HCL MEDIUM

This work concern with the electrochemical study related to eucalyptus leaves extract utilized as inhibitor towards mild steel' corrosion in various concentrations of HCl, at a temperature comparable to the average temperature in Iraq, at a temperature of 25°C.Electrochemical impedance spectroscopy and electrochemical polarization test methods were used to investigate this. The extract inhibition efficiencies and mild steel corrosion rate were calculated. The results show that the extract may be utilized as one of the effective inhibitors to prevent mild steel corrosion. The maximal efficiency of inhibition has been 99.77% at a concentration of 0.5 molarity, and the inhibition efficiency decreased with the increase in HCl concentration.

Decomposition of polyhalite with hydrochloric acid

Due to the fact that polyhalite ores are poorly soluble in water, it was of interest to study the method of their processing using acids. The influence of polyhalite size, the hydrochloric acid concentration and consumption, the ratio of L: S, the temperature and time of mixing the pulp on the useful components extraction into the solution have been studied. The optimal conditions for the decomposition of polyhalite with hydrochloric acid have been determined. The degree of useful components extraction into the solution depends on the concentration of hydrochloric acid or on the L:S ratio of the pulp, but in all cases the decomposition of polyhalite occurs without secondary crystal formation, as evidenced by the same degree of potassium and magnesium ions extraction. The degree of potassium and magnesium ions extraction from polyhalite into solution increases with decomposition process temperature, an increase in the consumption of acid and the duration of the reagents interaction, and decreases with increasing acid concentration. The CaSO4 content in the solution increases sharply with an increase in the HCl concentration and is practically independent of the process temperature. Hydrochloric acid extract can be used for phosphate raw decomposition in order to obtain complex fertilizers.